Accelerated oxidation tests: the Schaal method

The speed of oxidation, the duration of storage until the development of rancidity, the important factor in the processing and commercialization of fats, oils and fats that contain fat.

The degradation and rancidity of oils and fats can be sensed from the beginning, once volatile compounds appear. Exposing oils, fats or products to high temperatures accelerates the oxidation of the compounds. Therefore, methods are used to determine the oxidation efficiency of the structure, particularly when evaluating the efficacy of antioxidants to delay rancidity in these products.
There are several types of oxidation tests, such as the Rancimat Method, the Schaal Method, etc. In other articles, we have talked about the Rancimat Method which is a method that has been developed as a variation of the system AOM (active oxygen method), to determine the time of induction of fats and oils; with the typical application of Rancimat being the determination of the oxidation stability of fats and oils.

The Schaal test, also known as the oven test, was developed for the cookie industry. Through the test it was possible to choose butters that demonstrated the greatest resistance to rancidity. This test is used for animals, creams and products. Furnace tests at lower temperatures are used for products such as essential oils and cheese pastes, whereas elevated temperatures are aimed at volatile ingredients, such as Mamluk emulsions or modifications to the other original characteristics of the product.

Throughout this article we will explain what is the Schaal method and why it is widely used for its simplicity.

What is the Schaal method?

This accelerated oxidation test, called in English “Schaal Oven”, consists of storing the samples at a constant temperature for several days. The samples were kept at a constant and controlled temperature, above room temperature, normally at 60/63 degrees Celsius. The increase in temperature acts as a gesture and allows oxidation reactions, as well as measuring their evolution, both organoleptically (color, smell, taste, etc.) and by chemical analysis.

The samples are controlled for a period of days that may vary, depending on the degree of oxidation of the samples. This method is very common in companies in the food sector and is widely used due to its simplicity.

Throughout the duration of the test, fat is extracted cold from a fraction of the sample with petroleum ether. With this step already carried out, it is possible to determine the peroxide index to control the oxidation state.
The samples that are stable for more days will have more chances of success in the extensive tests, with their antioxidant systems being the best.

Exponential oxidation graphs are made from the data obtained in these measurements.
To improve the understanding of this essay, we will analyze its general execution procedure.


To perform a trial with the Schaal method, we must follow the following steps:

  • Set the oven to the desired storage temperature.
  • Label a sufficient number of 4-ounce bottles with proper identification to provide 3-5 bottles for each sample to be tested. To obtain valid comparative results, control samples (without antioxidants) should be included in this test. Code the samples to eliminate any bias from the organoleptic members of the panel. (Caution: Make sure that the labels used adhere to the bottles and remain legible during prolonged storage at elevated temperatures.)
  • Record in a laboratory notebook the identification of the sample and the date of the start of the test.
  • Fill marked jars from one third to half full with the desired test samples and cover the jars.
  • Place the jars in the oven to allow free circulation of hot air in the closed oven.
  • Evaluate the odors and / or colors (flavors) of the samples at appropriate intervals, using a trained organoleptic panel composed of at least three members. The duration of the interval between evaluations will depend on the nature of the individual sample. However, samples that have a relatively short Schaal furnace life (1 week or less) should be evaluated at 24-hour intervals, while samples that have a longer life in the furnace can be evaluated twice a week. A sample is removed from the oven when a stale odor or color has been detected by most of the panel members.
  • Record in the laboratory notebook the date on which each sample is removed from the oven.
  • Calculate for each sample the average days of rancidity (by smell or color) when all the replicas have been removed from the oven.
  • Calculate the results of the report as “Storage stability, such as days to develop rancid odor at a certain temperature.

Advantages and disadvantages of the Schaal Method

The main advantage is that it is a simple test, and does not require very specific equipment. It is also an assay that can be used for both oils and fats as well as for food samples.
One of the disadvantages is that although the use is simple, this test is very variable and is not practical as a routine analysis system. The reaction conditions are difficult to control in the case of repeated handling and the oxidations are very sensitive to the trace of contaminants in the crystals, additionally, it is not an automated test.

It is recommended if you need to obtain general estimates of oxidative stability.

The Halal certification in the food industry

To understand the meaning and implications of the Halal certification, it is important to understand the concept of Halal. This is a concept that covers the set of practices that are allowed by the Muslim religion and, although this term encompasses all kinds of practices, it is commonly associated with food that is acceptable according to Sharia, or Islamic law, being beneficial and healthy practices for people that provide less health risks and an improvement in the quality of life.

As we have just commented, today’s Muslims understand the term Halal as a lifestyle, a global and integral concept that influences and affects everyday issues such as food, hygiene, health, economics, fashion, trade and tourism. However, the use of the word “hala”l varies significantly between different Islamic communities.

In Muslim countries, the term is used to describe any practice permissible by Islamic law, having a more limited meaning to the literal, translated as permissible. This includes everything related to behaviour, language, clothing, manners and dietary laws.

However, in countries where Arabic is not spoken, the term is in most cases reduced to Islamic food laws, especially in terms of meat and poultry, although it is also used in more general terms.

This concept of “halal” has a great similarity with the Hebrew term “kosher”.

All that is prohibited,  harmful or abusive, are considered Haram, and according to the Islamic norm we can emphasise:

  • The meat of an animal that was found dead
  • The blood of an animal
  • Pork and wild boar, as well as their derivatives
  • Animals sacrificed without the invocation of the name of God
  • Carnivorous animals and scavengers, as well as birds with claws
  • Alcohol, alcoholic beverages, harmful or poisonous substances and toxic plants or drinks
  • Ingredients from animals or Haram products, such as pork gelatin. Additives, preservatives, colourings, flavourings, etc., produced from Haram ingredients
  • Interest, usury and abusive speculation
  • Gambling

Halal in the food industry

In general terms and in accordance with the above, to consider food Halal, it is necessary that it conforms to the Islamic law in the Koran, the traditions of Prophet Muhammad (SWS), and the teachings of Islamic lawyers . This implies that foods are fit to be consumed and are completly safe. In relation to the sector of the food industry, these are some of the most important conditions:

  • The product must be free of any prohibited substance or ingredient.
  • It must be a product made by using the appropriate utensils and machinery, which also cannot have been in contact with a prohibited substance or product during the process of making the product, nor during its production, processing, storage and transportation.
  • The animals that are allowed have to be slaughtered without unnecessary suffering and fulfilling the conditions that are stipulated.
  • Usually, fish are considered Halal.
  • Halal preservatives, colourants, flavourings or additives are allowed.
  • In animal feed, the feed must be of vegetable origin.

In relation to food labeling requirements, some additional requirements are established:

– When a declaration is made that the food is “halal”, the word “halal” or other equivalent terms shall appear on the label.

– In accordance with the Draft Revised Codex General Guidelines on Claims, “halal” claims should not be used in a way that could give rise to doubts about the safety of other similar foods, or in declarations of properties that suggest that “halal” foods are nutritionally superior or healthier than other foods.

The Codex Alimentarius Commission admits that there may be slight differences of opinion in the interpretation of what are licit and illicit animals and of manners of slaughter according to the different Islamic schools of thought. Therefore, these general guidelines are subject to interpretation by the competent authorities of importing countries. However, certificates issued by the religious authorities of the exporting country must be accepted in principle by the importing country, unless the latter justifies other specific requirements.

Halal Certification

It is the document issued by the Muslim authority of the exporting country in which it is certified that a certain agri-food or pharmaceutical product fulfills the requirements demanded by the Islamic Law for its consumption by the Muslim population.

The Halal Institute is one of the bodies that manage the Halal certification, and to obtain such certification it is necessary to meet the following requirements:

  • Not to include or contain in its composition anything that is considered unlawful under Islamic law.
  • Food must be prepared, processed, transported or stored using appliances or media that are exempt from what is unlawful under Islamic law.
  • Not having been in direct contact with other foods that do not meet the above requirements.

The procedure for obtaining certification includes the carrying out of company audits, through the documentary evaluation of the quality and production systems of the companies, by means of the evaluation of tests of samples taken at the factory and of the final products. At the same time, the personnel involved in the various stages of production are evaluated, such as slaughterers, cutting, processing, distribution, etc.

The certification process at the Halal Institute consists of the following phases:

  • Application for certification
  • Review of documentation
  • Audit phase 1 certification (correction of critical findings)
  • Audit phase 2 certification (correction of critical findings)
  • Evaluation and opinion
  • Initial certification issue
  • Annual renovation audit
  • Annual Certification Issuance

The conditions of certification require:

  • Comply with the Regulation of Use of the MGHJI.
  • Compliance by the company with mandatory declarations of production and sales of Halal products in form and frequency required by EGCH. S.L.
  • Comply with the training requirements.
  • Comply with the requirements of the Halal Warranty Mark of Islamic Board.

Kosher certification in the food industry

Kashrut (which pronunciation in Yiddish is “Kosher”) means “correct or appropriate to be consumed”. It refers to the Jewish precepts that determine exactly what food can and cannot be eaten; that is, which comply with the precepts of religion and which do not. Those who fulfill the precepts of the Kashrut are named Kosher.

Therefore, the Kashrut concept refers to the set of Jewish dietary laws found in the Torah (which is the text that contains the law and the identity heritage of the Israelite people). These are millennial old laws that determine foods that are pure and therefore are fit for consumption. In addition, these laws also indicate how they should be consumed and adapt to the latest food trends in the market.

Therefore, the Kosher certification that obtained certain products, indicates that these products respect the precepts of the Jewish religion, and they are considered pure and apt to be ingested by the practitioners of that religion. It groups from the composition and the ingredients of the product to the production process, putting a special attention in the preparation, and in the cleaning of the makeup as well.

Food is classified into 3 categories:

  • Dairy products (jalabí),
  • Meat (basarí)
  • Neutrals (parve).

Neutral foods can be consumed with dairy and meat products, but the prohibition on mixing meat and dairy products is excluded.

As an example, some considerations included in this certification are:

  • Meat food allowed are  ruminant animals and split hoof. Allowed birds are those that are not scavengers. In both cases, animals must be slaughtered according to Jewish regulations. The flesh of a pure animal, slaughtered according to regulations, and has passed all control becomes fit for consumption and receives the certificate of Kashrut.
  • As for fish, to be considered Kosher, aquatic animals should have scales and fins. Insects and worms are prohibited, as is sea food.
  • The process of making wine must be carried out in its entirety by the Jews from the moment they step on the grapes to its bottling.
  • Raisin consumption is not allowed, as they are coated with a non-Kosher base animal glycerin.
  • Chips can not be cooked  in the fryer in oil that has not been pasteurised and deodorised in the equipment used for the production of tallow.
  • The equipment used for the production of hot foods that are not Kosher may not be used for the production of Kosher products if the Koshering has not been realized.

The Kosher Market in the Food Industry

The Kosher market is estimated to be around $600 billion per year between products and ingredients.Muslims, vegetarians, vegans, people with allergies, etc. are also consumers of this type of products.

In addition, products with the Kosher certification are perceived as healthy, natural and of better quality.

Among the countries with the highest demand for products are United States, United Kingdom, Canada, Germany, Australia, Argentina, Israel, Italy, Norway, Poland and South Africa.

The market in the United States

In the United States there are over 100,000 Kosher certified products, and about 7,500 new products are certified each year. In general, only 20% of its consumers are Jewish. Consumers of both Kosher and Halal products are less influenced by discounts.

The popularity of these products among non-Jews is due in part to the perception of Kashrut as a good quality label. Users worried about animal suffering are also consumers of Kosher products. In recent years, some Kosher products have been very popular, ahead of “natural”, “no additives or preservatives” and “organic” products.

The average number of Kosher products in supermarkets is 25,000 products. Many consumers say they would buy more often if there were more product diversity.

Important supermarkets such as Pathmark, Wal-Mart, Shoprite and Albertsons have Kosher product departments. Albertsons, for example, provides Kosher sections at its 1750 points of sale in the USA. The growth in consumption of Kosher products is mainly due to basic foods such as cookies, chocolates and snacks.

Kosher certification in Spain

Kosher certification is a tool of differentiation and competitive positioning at an international level, in a market characterised by constant growth. This certification is important to promote exportation. Spain is a large manufacturer and exporter of food products. However, knowledge of export opportunities, especially in the United States, the most important market for Kosher products, is unknown in Spain.

Kosher certification has a good reputation, because it guarantees the quality of the products and is a competitive advantage in the large distribution of food.

The certification process covers all aspects of food production, from the ingredients used to the equipment used for production.

The Federation of Jewish Communities of Spain, through qualified personnel, supervises the Kashrut in Spain from the beginning of the production process until the packaging.

About Managing Kosher Certification

The Kosher Orthodox Union is the world’s largest and most recognised kosher certification agency, certifying more than 800,000 products produced in more than 8,500 plants located in 100 countries around the world.

The OU (Orthodox Union) seal is from the USA and is the most recognised. A product with this seal ensures that it has been made with Kosher ingredients and processed in an exclusive Kosher food kit.

How to apply for Kosher certification? In general the procedure entails the following steps:

– Request. Companies must complete an application, including the following information:

  • Company Profile
  • Profile of the production plant
  • List of raw materials
  • Product approval request

– An initial inspection and evaluation is carried out.

– Contract.

  • A- List of approved ingredients and raw materials.
  • B-List of brands and products certified with their designations. (OR for Parve; OU-D for daily; OU-Meat, OU-P for Pesach (Easter)

– New inspection and certification

History of antioxidants in food

Throughout history, fats and oils have been a fundamental part of human food due to their nutritional properties, their caloric intake and many other beneficial properties for food. They have even come to be regarded as authentic luxuries, within the reach of very few.

Since mankind began to accumulate and store their food, and subsequently to market it, people have always had to look for ways to protect fats and oils from spoilage and deterioration, devising different methods such as refrigeration or the use of additives to extend shelf life. Some of them have acted as real antioxidants in food.

In the use of the additives, the use of antioxidants was an ancient practice for food preservation (an antioxidant is a non-microbiological conservator), since, traditionally, meats and fish were cut into slices that were permeated with phenolic compounds that originated during the smoking process.

Subsequently, some researchers observed that the addition of small amounts of certain compounds could lead to a delay in the deterioration of other substances in the air.

Some of the researchers who came to these conclusions are:

  • Deschamps, an Avallon pharmacist, who demonstrated the antioxidant effect of benzoin and poplar buds.
  • Chevreuil, who checked the effect of oak.
  • The Lumiere and Seyewetz brothers discovered the antioxidant role of hydroquinone and analogous compounds.
  • Moureu and Dufraisse, who summarized their work in a memoir titled “Catalyse et autoxidation; Activité antioxygene et prooxygene “(1926)

With the passage of time and after the Second World War, where the ghost of hunger was present in society, poultry and pork production experienced a great increase. This growth is explained by the need to satisfy, in a fast and abundant way, the increasing demand for protein from animal origin;such an increase intensified the exploitation of these species, and therefore gave rise to a necessary adaptation.After this stage, in the mid-twentieth century and with the advent of globalization, the limits that impeded trade and stressed the need to adapt to the challenges and opportunities were met, increasing the export market and allowing a greater international presence. In this political and social framework, the need to search for factors that increase competitiveness such as the use of additives was a key factor in achieving efficiency for the industry.

To understand the importance of antioxidants as additives in the food industry, we must first understand what cell oxidation is. In a very general way, this occurs when an unstable atom loses an electron (negatively charged particle), which allows it to form a new compound with another element, causing an imbalance between the production of reactive oxygen species and the capacity of a system to cleanse the body of harmful substances. Historically, it was believed that adding oxygen to the fatty acid molecule formed a four-atom ring as the primary reaction product. This molecule is called “peroxide”. However, what is actually formed is a hydroperoxide due to the addition of oxygen to the alpha carbon of the double bond. In spite of this, the historical denomination still persists and peroxides are still used to refer to the products of the degradation of a fat.

The oxygen we use to breathe is one of the main responsible factors for cell oxidation, and serves to produce energy throughout the body, but small portions of this element produce free radicals, which form normally in the body when metabolized. Within our human organism exists a balance between reactive oxygen species and antioxidant defense systems. When this balance is altered or decompensated in favor of those, there is the so-called oxidative stress, which means that the stress can be triggered by solar radiation, inflammatory and immunological responses, alcoholism, smoking, vitamin deficiency and other factors.

Finally, we can conclude that antioxidants in food play an important role in modern technology in the treatment and conservation of food. Their correct use depends fundamentally on both the knowledge of the mechanisms of autoxidation and the factors that condition them, and on the nature of the processes on which the activity of the different anti-oxidation processes is based. What should be clear is that antioxidants can not improve the quality of a mediocre product. Therefore, the best means of limiting oxidative deterioration is to start from a quality product, to avoid the conditions favoring oxidation, and to conveniently exploit those combinations of the various types of antioxidant systems which may be used in each case and in each moment.

Food additives and E numbers

According to AECOSAN, the Spanish Agency for Consumer, Food Safety and Nutrition, “Food additives are substances that are added to foods with a technological purpose (to improve their appearance, texture, resistance to microorganisms, etc.) at different stages of their manufacturing, transportation or storage. ”

The widespread use of additives in the food industry makes them subject to control mechanisms that regulate their correct use.

The authorisation to use an additive is subject to three conditions:

  • A sufficient technological need can be demonstrated and when the sought objective cannot be achieved by other economically and technologically usable methods
  • They do not represent a danger to the health of the consumer in the proposed doses, to the extent that it is possible, according to theavailable scientific data
  • They do not mislead the consumer

Likewise, its necessity must be demonstrated in such a way that its use entails technological advantages and benefits for the consumer. The reasons for this need should be:

  • Preserving the nutritional quality of a food.
  • Providing  food to a group of consumers with special dietary needs.
  • Increasing the stability of a food or improving its organoleptic properties.
  • Encouraging the manufacturing, processing or storage of a food, provided that defective raw materials or inadequate manufacturing practices are not masked.

In the European Union, the authorization of a food additive requires an assessment of its safety by the European Food Safety Authority (EFSA).

When they become food components, they are considered ingredients and therefore must be included in food labeling.

The International Food Additive Numbering System (INS) has been developed by the Codex Committee on Food Additives and Contaminants (CCFAC) to establish an agreed international numerical system for the identification of food additives in the list of ingredients as an alternative To the declaration of the specific name, which is usually long and of a complex chemical nature. This system has come to be called “E Numbers Classification”.

As stipulated in the Codex General Standard for Labeling, identification numbers should only be used together with generic names that make sense to consumers as descriptions of the effective functions of food additives. For example, when tartrazine is used as a colourant in a food, it may be declared as “colour (tartrazine)” or “colour 102”.

Therefore, in relation to the form in which the additives must appear in the food labels, they are allowed to appear by their name or by the corresponding E-number, which is the code with which they are authorised by the competent authority . That is to say, when tocopherol-rich extract is used as an antioxidant, the labeling may include: “antioxidant (tocopherol rich extract)” or “antioxidant (E 306)”.

The labels appear as follows:

  • The letter E appears first. The fact that an additive has an assigned E number gives assurances that the additive has passed safety controls and that it has been approved for use in the European Union.
  • The following are the 3 or 4 digits:
  • The first digit indicates the category to which the additive belongs, the type of additive that is: E-1XX: dyes; E-2XX: preservatives; E-3XX: antioxidants; E-4XX: stabilizers, emulsifiers, thickeners, gelling agents and emulsifiers; E-5XX: acidulants, acidity correctors, anti-caking agents E-6XX: flavor enhancers; E-9XX: sweeteners, various
  • The second digit refers to the family of the additive (in the case of colourants it indicates colour, in that of antioxidants it indicates the chemical group to which they belong).
  • The remaining digits refer to the particular species and serves to identify the substance.

Here are 6 categories of food additives and their classification E numbers:


The practice of including dyes in foods has been existed for centuries, where some natural products like saffron were used in ancient civilizations. However, based on current regulations, many previously used dyes have been withdrawn from the market. Such dyes can be grouped into natural and synthetic dyes. The natural ones are considered in general as innocuous and therefore the limitations in their use are less than those related to the artificial dyes. The dyes are at the beginning of the table of Numbers E, covering the number 100 to 199.


We define preservatives as natural or artificial substances that are used in order to preserve food from the action of microorganisms, with the aim of preventing them from deteriorating within a certain period of time. Preservatives range from 200 to 299 in the E-number classification of food additives. Some examples of preservatives are Ascorbic Acid (E200), Lactic Acid (E270) or Potassium Propionate (E283).


We can find the antioxidants in the list of Numbers E, in the range between number 300 and 399.

Dr. B. Halliwell defines antioxidants as, “substances that are in low concentrations with respect to biomolecules that protect, prevent or reduce the damage they undergo due to oxidation”. These are substances that aim to extend the useful life of the product, delaying oxidative rancidity and therefore oxidation of food. In the field of antioxidants, there are also natural and synthetic. Specifically, the market for natural antioxidants such as the extract rich in tocopherols (E306) is on the rise, among other reasons, due to the noticeable change in society of seeking more and more natural ingredients. Regarding synthetic antioxidants, BHA (E320) and BHT (E321) have more traditionally been used by the food industry.

Stabilizers, thickeners, emulsifiers:

The first digit of these food additives in the list of E numbers is 4, i.e. those indicated with 4XX.

The purpose of these additives is to provide some texture and density. In the case of thickeners, they have the capacity of absorbing some of the liquid from food and are used in foods such as creams, sauces and shakes. Stabilisers aim to make the ingredients not dispersed in certain mixtures. Some thickeners such as xanthan gum, whose E Number E415 are widely used in haute cuisine for textures.


These additives have a very specific function as they are used in food to provide a sweeter taste. There are natural or artificial (synthetic) sweeteners and they have the highest digits in the food additive table, since they are within the 9th digit. Some common sweeteners are Stevioside Extract (E960) Or Saccharin (E954).


Flavourings are, according to FAO’s definition, “products added to foods to impart, modify or accentuate the aroma of food (with the exception of flavour enhancers considered as food additives under generic names and international system Codex Alimentarius Numbering – CAC / GL 36-1989). Flavourings do not include substances which have an exclusively sweet, bitter or salty taste (e.g. sugar, vinegar and table salt) “. Some flavors are glutamic acid (E620), calcium glutamate (E623) or calcium guanylate (E629). They share the number 6 as the first digit within the classification.

In short, it is important to emphasize that food additives are regulated by the European Union and classified in a list with the number E corresponding to each additive, in order to have a control over them, and that each type of additive is grouped within a numerical range.

Stabilizing fats and oils. Interview with Víctor León, Head of Laboratory at BTSA

A few days ago, Víctor León Fernández, our Head of Laboratory, was interviewed about the important need to stabilize food fats and oils.

Víctor León has a degree in Fundamental Biology from the University of Salamanca, with extensive experience in the sector, and is the Director of Quality and R & D Laboratory at BTSA. He is  considered to be an expert specialist in the treatment of fat.

Here we have transcribed the interview, which, as you can see, conveys in a clear and simple way some concepts, which, by their nature, are sometimes difficult to understand.

What is the definition of fats?

In biochemical terms, the concept of fat is used to designate various kinds of lipids, usually the fatty acid esters with glycerol, forming the so-called acyl glycerides (monoglycerides, diglycerides and triglycerides).

Some common characteristics of fats are their insolubility in water and their density is significantly lower.

With what other names can we define fats?

Commonly fats are those that are solid triglycerides at room temperature, while those that are in the liquid state are known as oils. The origin of these compounds can be of both animal and plant origin.

What is the role of fats in human food?

Fats are responsible for many functions within the body, as they are essential elements for life.

In this way, we can say that they are nutrients that contribute energy to the organism (up to 30%), constitute the energy reserve to form part of the adipose tissue, and collaborate in the regulation of body temperature.

They facilitate the transport of liposoluble vitamins and are a component of a large number of hormones and cell membranes, making them an essential part of the diet.

How does self-oxidation of fats occur?

Lipid oxidation is a common phenomenon in fats, in which, after exposure to oxygen, a chain reaction is generated, resulting in free radicals. This causes the degradation of the fat manifested sensory in the form of rancidity, and associated with bad odours and unpleasant flavors.

The presence of some metals and peroxide radicals, as well as energy from light can also trigger oxidation phenomena.


Victor León, Head of Laboratory at BTSA

Why is it necessary to stabilise fats? Explain the concept of stabilisation

The concept of stabilisation refers to the protection of fats against the auto-oxidative processes mentioned above, so that free radicals are prevented or hindered and consequently the appearance of the rancidity effects are delayed .

The stabilisation of fat extends shelf life extension, preserving its nutritional and organoleptic properties for a longer time, which is a benefit not only at the food level, but also industrially and economically.

How can fats be made more stable?

The most commonly used form by the food industry to stabilise fats is the addition of antioxidants, substances that, generally by means of chemical mechanisms, prevent the development of free radicals and as a consequence,rancidity.

For what type of food and / or processes in the food industry does the fat stabilisation necessary?

All foods with some fatty content, which are the majority, are susceptible to be stabilised.

From my point of view, it is a mistake to think that only those with a high fat content should have antioxidantsadded to them, since others, with lower fat content, can drastically modify their organoleptic characteristics if the lipid fraction they contain oxidizes, representing a detriment to the whole product.

It is the case of foods with nuts or essential oils, usually with a low representativity in the rest of the product, but when oxidised produce unwanted aromas and flavours throughout the product, which reduces palatability.

What studies are done at BTSA on fat stabilisation?

BTSA is a natural antioxidant company with more than 25 years of experience in the sector.

The most common studies of stabilisation and antioxidant effectiveness are usually carried out using techniques known as “accelerated oxidation”, such as the RANCIMAT, RapidOxy or Schaal analysis.

The general principle of these studies is accelerated degradation-oxidation of fats by action and effect of temperature, pressure and oxygen flow on controlled, stabilised or blank samples, to measure the changes produced by the various antioxidants.

We currently have a group of experts in the field and a collection of more than 300 studies with different antioxidants on various lipid matrices.

Personal vision

There are a multitude of antioxidants to stabilise fats, natural and synthetic, with wide trajectory or in development phase.

In our company we have always opted for a natural vision of them, on the cutting edge of science and always with the aim of improving the formulas we have, as well as providing customised solutions for our customers, a fundamental premise given the great variety of foods and Industrial techniques present in everyday food.

Main exhibitions in the food industry

Due to food science and technology, the progress of the industry has increased along with customers interest in healthy nutrition. The increase in production has been combined with a progressive effort in monitoring the hygiene and the food laws of the countries trying to regulate and unify processes and products. Considering all of this, it is a dynamic sector in which innovation is a factor of utmost importance to produce more and better.

In this article, we are going to present some of the main exhibitions that are of high interest for food manufacturers for sharing information, networking and learning more between all the agents of the different segments of the market. This is a way to share new knowledge and to catch up with the news and trends in the food industry.

Food Ingredients Europe and Asia

Food Ingredients Global provides customised solutions for companies that need to grow and develop their business.

Food Ingredients Europe is held every two years in November and is one of the most relevant meetings in which you can meet the main suppliers of ingredients for food. The attendees at this fair can be up to 13000 people, and they have around 570 exhibitors.

The sectors and products represented are mainly from the food and beverage industry, but there are companies from the chemical, pharmaceutical and cosmetic industries as well. With regard to ingredients, we offer vitamins, minerals and additives, dietary supplements and nutraceuticals and natural colors, as well as measuring equipment.

For its part, Food Ingredients Asia (FI Asia) is an event that has been developed since 1996 for the service of the extensive food industry of Southeast Asia and it usually occurs in September, summoning 17,000 attendees and counting on more than 400 exhibitors.

In 2010, the decision was made to rotate between Thailand and Indonesia to access the entire region of suppliers of key ingredients and quality visitors. To support this important exhibition, smaller summits have also been introduced in Vietnam and the Philippines.

This region is recognised by industry and leading market research companies as one of the leading emerging markets for food ingredients. The Southeast Asian market is booming, with a population of over 625 million. FI Asia is a platform for large and small businesses to increase their exposure in the Asian region and boost their business, with annual growth of 25% in the number of exhibitors in the last four years.

Vitafoods Europe

Vitafoods Europe is one of the sector fairs for ingredients of nutraceutical products and dietary supplements, and it normally takes place in May. It is one of the main events in the nutraceutical sector, and related products and services around the world, where around 1,700 visitors and about 900 exhibitors are attending.

During the fair, presentations are given on current issues relevant to the sector, such as the importance of traceability in food, healthy alternatives to snacks and R & D for the future consumer.

In addition there are alternative activities, such as an educational program divided into three main pillars: R & D forums, business workshops and probiotic summit.

Natural Product Expo East and West

Natural Product Expo West is an organic, healthy and natural products industry fair that attracts more than 80,000 industry professionals and 3100 exhibitors to the Anaheim Convention Center. It is a very relevant fair in the sector, and the usual date is in March. It is ranked as one of the 200 most important fairs in the United States by Tradeshow Week, as is the version of this fair on the east coast, Natural Products Expo East.

Natural Products Expo East takes place on the east coast of the United States, and more than 28,000 professionals meet. It is an organic, healthy, natural products industry fair, and has 1,900 exhibitors and is held at the Baltimore Convention Center. Some of the activities included  in this fair are the conferences, workshops and tours. In addition, there are many other activities included in this fair, such as Retailer of the Year Award Ceremony, Thursday Evening Celebration and Community Breakfast.


This is the food technology fair where some of the industry’s most creative minds meet, and it is usually held in June at the McCormick Place fairgrounds facility in Chicago, although in 2017 the fair took place in Las Vegas. With more than 20,000 attendees, the companies that participanted can build new relationships and expand their professional ecosystem in their more than 1000 exhibitors, and enjoy about 100 sessions where they can expand knowledge.

At the event, attendees can find a large collection of food ingredients, equipment, processing and packaging suppliers. It is a leading event in its category, where food trends are exhibited worldwide.

Supply Side West

Supply Side West brings together more than 15,000 buyers of ingredients and suppliers from the dietary supplements, beverages, functional foods, personal care and sports nutrition industries.At this fair, which is usually organised at the end of September or beginning of October, you can learn about the new trends in the world food industry. The event brings together more than 1,200 exhibitors and has more than 140 hours of educational and conference programming.

FoodTech Summit

The Food Tech Summit & Expo is a food industry event that brings together ingredients, additives and solutions for the food and beverage industry in Mexico and Central America. In its next edition, it will celebrate 10 years and the usual date of the fair is in September.

Participating in this fair means presenting the products and / or services to more than 13,000 executives who visit the Expo with 350 exhibitors.

In addition, international speakers come to present trends, best practices, success stories and share strategic information about the industry. This event is mainly directed to directors, managers, coordinators, analysts, representatives of the areas of: R & D, new products, marketing, shopping, commercial, production, quality and laboratory, among other areas.


With more than 50 years, this fair is focused on the Australian food manufacturing industry. Foodpro is organised once every three years, usually in July, and is located at the Melbourne Convention & Exhibition Center. The number of attendees is around 9,000 and the number of exhibitors amounts to 360.

This event provides a platform for food industry professionals to meet face-to-face with suppliers of state-of-the-art processing, packaging and production technology as well as the latest in food science.

The visitor can explore through the six zones of Foodpro, each dedicated to the different steps in the food manufacturing process: Ingredients, Food Science and Technology, Processing Equipment, Plant Equipment, Containers and the New Zone Integrity of the Supply Chain.


Gulfood is the annual food and beverage fair that brings together food professionals from all corners of the world to meet for 5 days. Gulfood is a professionally managed B2B fair hosted by the Dubai World Trade Center (DWTC), which is normally held in February. At first it was a biennial event, but the fair has grown to promote food trade among more than 120 countries a year, allowing 5000 suppliers of raw materials and ingredients to show trends and innovations that are shaping the future Of food and drink consumption worldwide. The participation of this fair is high, with around 93,000 attendees.

Below, we show a summary table of the most significant data of each of the fairs.

fairs table.jpg

Clean Label: Facts and Trends

It is increasingly common for E-numbers to be misleading to consumers, who demand products whose labels can be clearly understood and contain no unnecessary chemicals. Consumers are increasingly paying attention to the composition of foodstuffs and also how this is communicated in the packaging. Clean Label responds to the growing demand for information and transparency by consumers. “Clean labeling” is no longer a trend but rather a consumer demand, to which the industry in general is responding, putting more and more emphasis on these aspects in food packaging.
Although there is no official regulation on “clean labeling” (Clean Label), we can analyse the guidelines that different bodies or interest groups show in this regard.

The National Center for Food Technology and Security (CNTA) has manifested, through its leaders, the challenge for the industry to keep consumers in a growing need to eat increasingly natural foods, and propose three ways to help companies to get it:

  •  First, it is important to consider the latest trends in natural ingredients to replace conventional additives.
  •  Secondly, a good path may be the use of new conservation technologies which are less aggressive and more respectful of the sensory and nutritional characteristics of food.
  •  Finally, we have alternatives in packaging, with the use of materials with functional antifungal, antimicrobial or oxygen hijackers (to avoid oxidation problems).

Non-Profit Organizations

There are different organizations like Clean Label Project ™ that are contributing their vision on clean labeling with the aim of educating people so that they are more informed when buying products. The philosophy of this project is based on being able to clarify to consumers what it is that the label does not tell them. That is, they look behind the ingredients, industrial or environmental pollutants that may exist to inform the consumer before they purchase the product. Product evaluations are based on chemical analyses and the organisation does not make guesses or assumptions about data provided by companies or other consumer associations, but simply conduct studies and publish data objectively.

How Clean Label Project ™ works: they buy and analyse hundreds of products that represent 90% of the best brands in their category. Blind tests are performed in independent laboratories and the results are validated by two other laboratories. The data obtained after the laboratory analyses are analysed and compared by their own doctors. With the results, and in order to keep consumers informed, Clean Label Project ™ uses a 5-star rating system available on the web to rate products that have gone through the review process.
In short, this organisation aims to educate consumers, so they are aware of what they are buying. The way they do it is through scientific data, identifying toxins and sharing information with consumers. They also consider it important to understand what types of pollutants and products are being tested and their potential effects.

On the website of this non-profit organization, there is a list of pollutants that they analyse, along with some of the figures for each of these pollutants.

Leading companies in the food industry.
Several private companies have conducted their own studies focusing on the perception of consumers regarding food labeling. Some of the most important statistics that emerge from their surveys are those concerning the level of consumer awareness regarding the ingredients of processed food and the acceptance of these ingredients.
Based on these studies, the main consumer trends in this area are:

  •  Consumers are wary of those food terms they are unfamiliar with, whether natural or synthetic. Terms like “Natural flavours”, “Rosemary extract” or “certain natural antioxidants” have a good acceptance among consumers, because they are related to natural concepts. In contrast, certain colourants and flavourings, or synthetic antioxidants such as BHA, BHT or TBHQ have poor consumer perception. Even concepts such as E numbers are not well evaluated, regardless of the fact that much of these additives are naturally occurring.
  • Another point of the data that emerges from this survey is one concerning acceptance, where it can be seen that 2 out of 3 consumers consider that a product containing artificial ingredients should not be considered natural.
  • Regarding applications, the products in which most respondents think that there should be no artificial products is in meat, dairy and cereals.
  • On the other hand, according to these companies, “Clean label” is no longer a trend, but a reality included in the labeling of food products. But what is the formula that should be included in the labeling for consumers to identify it as “Clean Label” in the labeling?
    • Clarity: 3 out of 4 respondents normally read the list of ingredients, and identify “without artificial ingredients” and “without additives or preservatives” as the most important identifiers to associate that product as a natural product or Clean Label.
    • Consciousness: Consumers seek directly the brands they normally consume to be environmentally conscious in their manufacturing processes, such as packaging, supply and responsible livestock. Consumers are looking for brands that not only think about supply in the short term but also about care of the environment and the planet in the long term.
    • Connection: the millennials’’ tendency, on the other hand, is to buy brands with which they have a greater connection and not those that buy their parents. They are interested in knowing what is behind brands such as origin, responsible practices and people.
    • Credibility: because of the greater information that users receive about the ingredients, they are more aware of what they buy and what they consume, so they demand more accurate and credible information. For example, there has been a confusion between the term “Natural” and “All natural” used as claims, which has caused skepticism in society.

Companies specialising in market research

In the USA, other surveys have been conducted from where very interesting data for the industry came out.
With regard to production, consumers demand greater transparency. For example, 68% of consumers consider it important to see the product through the packaging before buying it. 25% of consumers between 18 and 34 have scanned QR codes in the wrapper with a mobile device to obtain information.

28% of users consider it an unhealthy product if it contains artificial ingredients. Thirty percent of consumers surveyed admit that they would buy more products from the store brand if they contained easily recognizable ingredients. 32% of consumers agree that the “natural” claim is good for health. Also 34% of respondents identified with the phrase, “I buy more organic food than I bought a year ago.”

As a final conclusion we can say that although there is no official body or health authorities that clearly define what is “Clean Label” and when this concept can be used, what does seem to be increasingly clear is that users have more information, so they demand more clarity about what they buy and consume, with the aim of consuming more and more natural products. In this sense, it is clear that there is a tendency in the food sector towards the natural and sustainable.

Accelerated oxidation tests: the Rancimat method


The decomposition of vegetable oils and animal fats, which can be perceived in the initial stage through a deterioration of smell and taste (rancidity), is a result of a series of chemical alterations caused mainly by the effect of oxygen. These oxidation processes that progress slowly at ambient temperatures are called auto-oxidation.

They begin with radical reactions on unsaturated fatty acids and are in a process that involves multiple stages, resulting in various decomposition products, in particular peroxides as primary oxidation products and alcohols, and aldehydes and carboxylic acids as secondary oxidation products.

The Rancimat method consists of a measure of the conductivity of the volatile compounds that are formed from the oxidation. This method has been developed as a variant of the complex AOM system (active oxygen method) in order to determine the induction time of fats and oils.

The determination of the stability to the oxidation of oils and fats is the typical use of Rancimat. In addition to oils and vegetable fats, with Rancimat it is also possible to analyze animal fats and determine their stability to oxidation.

Precisely the pure substances of oils and fats contained in foods are subject to oxidation, which contribute to the deterioration of food. Rancimat can also be used to determine the oxidation stability of fats and oils in food.

Stability to oxidation indicates the resistance to oxidation of oils and fats and foods containing fat. It is a standard parameter of quality control in the production of oils and fats in the food industry or for food inspection in modern processing plants.

Oxidative Stability Procedure: The Rancimat Method

With the Rancimat method, a sample exposes an airflow at a constant temperature between 50 to… 220 ° C, according to the following figure:


To determine the oxidation stability, an air stream is passed through the sample of fat or oil at a high temperature. This causes the oxidation of the sample’s fat molecules in volatile organic compounds and other products. Highly volatile secondary oxidation products (mostly formic acid) are transferred to the measuring vessel with the airflow, where they are absorbed into the measuring solution (distilled water). Here the conductivity is continuously recorded. Organic acids can thus be detected by increasing conductivity. The time that passes until appearance of these secondary reaction products is called induction time or induction period, which is a good indicator for oxidation stability, as it characterises the resistance of fats and oils to oxidation. In this technique, the conductivity, recorded continuously, draws a curve whose inflection point marks the period of induction from which a drastic increase of the same is produced, linked to the increase of volatile oxidation products, as shown in the following figure :

Periodo de induccion Rancimat.png

Figure obtained from the manual 743 Rancimat

In addition to the term induction time, the expression is used: Oxidative Stability Index (OSI) (Oil Stability Index). The Rancimat method is also known as the “Rapid Oxidative Stability Test”


This is a standardised and commonly accepted method, but can lead to errors, such as any trace being left in the tubes or even the vaseline used to close them, which can increase the conductivity.

Certain free fatty acids of low molecular weight that make up some oils can even volatilise at those temperatures (100 ° -120 ° C) also giving an increase in conductivity.

On the other hand, certain antioxidants are volatilised at those temperatures which causes not only an increase of the conductivity, but also they are totally ineffective because they do not remain in the oil that they are meant to protect.

Application examples

Stability to oxidation of fats and oils: If fats and oils are exposed to air and light for a long time, they oxidize and are subject to hydrolysis reactions. Fats and oils then have an unpleasant taste and smell and become stale. Stability to oxidation makes it possible to estimate the speed with which a grease or oil becomes rancid. By using Rancimat it is also possible to characterise the effectiveness of antioxidant additives.

Oxidation stability of instant noodles: An example of the use of Rancimat is the determination of the oxidation stability of fast cooking pastas. The pastas are fried in a fat or oil bath during the processing process to allow rapid cooking by the consumer. Because of this previous frying, instant noodles are high in fat (up to 22%) and become stale after a while.

Stability to Walnut Oxidation: The microstructure of fresh, intact walnuts prevents rapid oxidative deterioration. But this microstructure is destroyed during the processing of nuts. This accelerates the oxidation of fats and reduces the shelf life. Before the oxidation stability of walnuts can be determined, it is necessary to separate the fat-containing phase from the rest of the walnut using petroleum ether. The isolated fat is analyzed in the Rancimat.

Stability to oxidation of biscuits or other bakery products: The Rancimat method is a simple technique for determining the oxidation stability of fats contained in cereals, biscuits, breads and other baked goods.

The oxidation process in fats and oils

The oxidation of fats is one of the main causes of deterioration of food along with the action of microorganisms. It results in alterations of aroma and flavour, colour, loss of certain nutrients and the formation of potentially harmful substances, which leads to a reduction in the shelf life of the food. This process has important economic repercussions because the food becomes unfit for consumption.

The oxidative process of fats causes a decrease in the nutritional capacity of the food by the destruction of fat-soluble vitamins and the degradation of polyunsaturated acids.

Food safety can also be affected, since the products originating from the oxidation can present toxicity, some volatile products, peroxides, oxy acids etc.

This article aims to describe the oxidative process of lipids and therefore the importance of the use of antioxidant substances. To do this, we will focus on the oxidation process of fats and the main factors that influence the oxidation of fats

Oxidation of fats

The main oxidation form of lipids occurs through a free radical chain propagation reaction, in which peroxides and hydroperoxides are formed from fatty acids and oxygen, which is known as the auto-oxidation process. These compounds are quite unstable, so they can be broken, giving rise to more free radicals and generating a chain reaction.

Historically, it was believed that adding oxygen to the fatty acid molecule formed a four-atom ring as the primary reaction product. This molecule is called “peroxide”. However, what is actually formed is a hydroperoxide due to the addition of oxygen to the alpha carbon of the double bond. Despite this, the inaccurate idea still persists and peroxides still refer to the products of the degradation of a fat.

Auto-oxidation is an irreversible oxidation process of fats. It is impossible to avoid it in its entirety, but it can be delayed due to the addition of antioxidants.

The oxidation mechanism consists of three phases:

  • Induction: The initiators are usually energy (light, heat, etc.), traces of heavy metals, and radical peroxides that cause active free radicals to occur. The action of the energy causes the decomposition of the fatty acid in a free radical and hydrogen ion, as shown in the following figure:

Fase 1 Induccion-en.png

  • Propagation: With the oxidation of free radicals in combination with other fatty acids, hydroperoxides and more free radicals are formed, which re-enter the oxidation chain. On the other hand, hydroperoxides with the incidence of energy, form oxydryl groups and the oxidized form of free radicals, which together with other fatty acids give rise to more hydroperoxides and new free radicals. Finally, the oxydryl groups along with other fatty acids release water and new free radicals exposed to a new oxidation.

Fase de propagacion de la oxidacion-en.png

  • End: The amount of reactive compounds is huge and begin to interact with each other. The concentration of peroxide radicals falls as the formation of deteriorated products begins to stabilise. Given the stability of the products originating in the termination reactions, the oxidation activity is terminated. The auto-oxidation of fats continues to be affected by a free radical and the action of temperature and light. The formation of new chains favor the acceleration of the overall reaction, in addition the reaction capacity is favored in the presence of certain metals like copper and iron.

Fase de final de la oxidacion-en.png
After the complete destruction of the fatty acids, secondary products of oxidation are generated, which are responsible for the occurrence of rancidity.

To delay or prevent the oxidation of fats and the rancidity of foods, it is necessary to know how to prevent the formation of the first free radicals or first hydroperoxides, since this can only be achieved during the first stage of the oxidative process, during initiation. On the contrary, once the oxidative process reaches the propagation phase, said process can no longer be delayed or stopped.

 Factors that influence oxidation

The factors that influence oxidation may be intrinsic and / or extrinsic to the food, that is to say, they can be regarding the product and the  applied technology. Some of the most relevant are mentioned below (Dr. Paucar Penacho, Deterioration of Agroindustrial Products – 2014):

  • Temperature; The rate of auto-oxidation increases with temperature. It can affect not only the auto-oxidation rate, but also the reaction mechanisms.
  • Light: Fatty acids and their peroxides are colorless substances that do not absorb visible light. Thus, unless an accessory sensitiser is present, it can be assumed that the effect of visible light on autoxidation is not of greater importance. However, ultraviolet light is strongly absorbed in the unsaturated compounds.
  • Oxygen: The rate of auto-oxidation increases with increasing oxygen pressure, until it reaches a constant rate of reaction.
  • Humidity: The effect of water activity on the oxidation rate of lipids is very complex. Rancidity develops rapidly at both very high and very low moisture levels. Maximum stability is observed at intermediate moisture levels corresponding to monolayer values (protective effect of water in the form of a monolayer).
  • Ionizing Radiation: One of the most notable effects of high energy irradiation on food is a marked increase in the susceptibility of oxidative rancidity.
  • Catalysts: Heavy metal ions are powerful catalysts for the oxidation of lipids, decrease the induction period and increase the rate of reaction.

As a conclusion we indicate that to inhibit, reduce or delay the oxidation of lipids, it is necessary to act against one or more of the factors that encourage its development.

In a broad sense, it is considered as an antioxidant any substance or process of action that helps to limit the speed and / or extension of oxidative processes. According to this concept, three types of antioxidants could be considered, depending on their mechanism of action. The first two types are associated with the addition of chemical compounds, while the third owes its action to modifications of certain factors in the food and / or in its processing.

In the next articles we will analyse in detail the classification and action of the antioxidants for use in food.