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Wheat flour primary bakery ingredient, hence safety of flour important
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Monday, 07 January, 2019, 08 : 00 AM [IST]
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Dr Ramalingam C, Adrija Choudhury
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Dr Ramalingam C, Adrija Choudhury, Pradyumn Maheshwari, Parnika Pathak
Introduction In today’s world baking is a thriving industry. This increased popularity has led to a proportional increase in competition and hence a demand for perfection. Baking is a process of cooking by dry heat. Bread is one of the most popular bakery items. Cakes, next to the bread, are one of the most popular bakery items savoured worldwide. Other bakery products include biscuits, crackers and cookies which come in various flavours and varieties. Pastries and wafers are also present in the list of bakery products.
The annual growth of the bakery industry in India accounts for 15%. In India, the majority of the baking scenario is occupied by the unorganised sector which has a total of approximately 90% of the shares. The leading baking industries in India are Parle Products Pvt. Ltd, Britannia Industries Ltd, Priya Gold Biscuits, Anmol, ITC foods and so on.
Ingredients in baking
Baking of the bread starts with yeast. It releases carbon dioxide during respiration which is what makes bread fluffy and leads to its expansion. In the process of making cakes, baking soda is added to generate carbon dioxide.
The base ingredient
The base ingredient of all bakery products is flour. Flour separates the ingredients and also helps impart a balanced taste and texture to the baked product. Gluten, a protein found in wheat, which is composed of glutenins and gliadins is responsible for giving a firm structure to the baking products. An optimal gluten content gives dough machinability, good gas retention and hence a higher bread volume.
Eggs
Flour from different sources is being used in the baking industry like ragi flour, urad dal flour and besan flour. Eggs are added as a rich source of proteins and fats, which act as a binding agent. It has lipids which gives a softer texture due to retention of the moisture and a brown colour to baked goods. Lipids form inclusion bodies with the polysaccharides which break the crystalline structure of starch hence makes the bread softer.
Milk, sour cream, cheese
Products like milk, sour cream, cheese, condensed milk are widely used in baking to increase binding efficiency and activity of chemical leaveners. Sweeteners, generally molasses and honey or their blend, are added which apart from adding sweetness to the product make it flavourful and tender.
Sugar
Upon heating, the sugar caramelises to give a brown colour and an aroma to the baked product. This is due to the Maillard reaction where a reducing sugar reacts with an amino acid to give products responsible for the brown colouring.
A replacement for sugar is used i.e., artificial sweeteners like sucralose are used in baking but they do not provide the texture similar to as that of the sugars. Aspartame a very popular artificial sweetener cannot be used as baking at high temperature leads to a chemical reaction thereby giving the product slightly bitter taste.To slow the process of deterioration of the baking goods preservatives like sodium benzoate, sodium nitrite and propylparaben are used.
Safety of bakery ingredients
Out of the aforementioned ingredients, flour, particularly wheat flour is the major ingredient of bakery industry across all nations. Hence the safety of flour raises a major concern.
In the year 1987, Kashmir saw an outbreak of tricothecene mycotoxicosis which was caused due to consumption of infected wheat, a part of the bread sold by local sellers. It was observed that the quality of the bread sold around that time was bad which had a chewy nature and bad crumb qualities. Further tests on the affected flour yielded results that confirmed the presence of toxic Fusarium species of fungi.
More consistent and better
Additives are added to make the quality of flour more consistent and better. Most of the additives work synergistically, i.e., they complement each other. Some of the additives added to flour are ascorbic acid (vitamin C), L-cysteine, bromate, azodicarbonamide, sodium stearoyl lactylate, glycerides, and calcium peroxide. These chemicals must be strictly regulated and added in the most optimum amount. If not, they can pose a threat to the human body.
Prove to be toxic or carcinogenic
Some of these additives can form intermediate compounds which can prove to be toxic or carcinogenic. The amino acid aspargine present in flour can react with sugars at high temperature during the baking process and form acrylamide, which is listed as a potential carcinogen. To remove this, the enzyme asparginase is added which converts aspargine to aspartic acid and hence cannot form the toxic product.
Bromate and ascorbic acid is added as an oxidising agent. While ascorbic acid is not harmful as an additive, the same cannot be said about bromate. It is added as potassium bromate which has been proved to be carcinogenic and nephrotoxic to humans.
Cause adverse affects
Potassium bromate is usually added in the range of 70 parts per million of flour or less than 45 parts per million of dough which falls within the permissible range. Most of the potassium bromate in the flour during the baking process is converted to potassium bromide which is not lethal though trace amount can still remain and cause adverse affects.
Nowadays baking industries use the enzyme glucose oxidase as an oxidising agent. L-cysteine acts as a reducing agent and a free radical scavenging agent when added to flour. The main mechanism through which it acts is by reducing the disulfide bonds present in gluten and hence affecting the rheological properties of the flour.
The chemical Azodicarbonamide (ADA) is used as a dough conditioner and helps flour attain a fine texture hence giving a white finish to it. Recent studies have found that semicarbazide was formed when azodicarbonamide is subjected to the baking process with the intermediate biurea.
Carcinogenic and genotoxic effects
Semicarbazide has been experimentally proved to have carcinogenic effects and genotoxic effects. There is no optimum concentration of azodicarbonamide through which semicarbazide is not formed but studies have shown that reducing the concentration of azodicarbonamide and reducing the baking time will decrease the concentration of semicarbazide.
Bakers yeast which is actually Saccharomyces cerevisiae is the most common species of yeast used for baking purposes. It can be procured in a liquid form or a creamy form or as active dry yeast. The active dry yeast can be used directly without taking measures to rehydrate it. The other widely used ingredient is milk. It has very high moisture content, being practically a liquid, which can promote the growth of spoilage microbes. It was found that most of the pathogens were being transferred from faecal matter of the cow which is being milked.
There is an increasing number of detection of food pathogens being present in pasteurised milk thereby implying that the pathogens cannot be fully eliminated by this process alone.
High microbial contamination
Pathogens like Listeria monocytogenes can recontaminate pasteurised milk as it can survive the process of pasteurisation. The permissible TPC (Total Plate Count) of microbes in raw milk is 106 cfu/ml. The samples collected from Indian dairy farms had a highest of 13.9 x 106 cfu/ml and a lowest of 11.7 x 106 cfu/ml hence indicating high microbial contamination.
Cholesterol present in milk and egg-two of the main ingredients in the baking process can undergo auto-oxidation to form sterol oxides. Yeast can also have sterol oxides. This product has been experimentally found to have cytotoxic, apoptotic and inflammatory effects. When these ingredients are mixed with flour containing oxidising agents like ascorbic acid or potassium bromate the oxidation of cholesterols present is accelerated and sterol oxides are produced.
Bakery products themselves have a high water activity of more than 0.85. Water activity tells us the presence of unbound water present in a food material which can be used by a microbe for its growth. The majority of Bacillus species found in the baked foods is primarily from the food ingredients used for the baking process.
Mould growth is one of the most serious issues in the bakery industry since it grows well in foods having a water activity of more than 0.8. The spores of moulds are inactivated and killed during the high heat of the baking process but recontamination happens during food handling and wrapping operations. This means that all of the mould contamination happens after the process of baking. The spoilage can be controlled by taking the measures like reduction in the water activity of food by dehydration process, freezing and adding preservatives.
Conclusion
Bakery industry in India has a huge market due to the high nutritional values of baked products and ease of availability of the raw materials. The safety of the ingredients used is of a major concern. The most common ingredients - wheat flour, food grade yeast and milk used in the bakery industry should have stringent checking for presence of microbes as the most common source of bacterial contamination are the raw ingredients.
The additives added to obtain better quality flour are mainly oxidising agents like ascorbic acid and potassium bromate, reducing agent like L-cysteine and azodicarbonamide and surface acting agents in short, surfactants like glycerides and sodium stearoyl lactylate.
These additives can react with different chemicals present due to combination of various sources for example cholesterols in milk and oxidising agents in flour can accelerate oxysterol formation. These additives can also form toxic products at high temperature which is used during baking.
Hence these chemicals should be investigated for all possible interactions with other active ingredients before being added in baked products to ensure safety of the consumers. Baked products themselves are prone to spoilage by bacterial and fungal sources. Measures like dehydrating, quick freezing and use of natural preservatives help in preventing microbial spoilage.
(Ramalingam is sr professor, SBST; Choudhury; Maheshwari; and Pathak are BTech students, Vellore Institute of Technology, Vellore)
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