In the modern era, modification of foods has become a common practice. Due to the versatility of dairy ingredients, this industry has been a favourite venue for technologists to play along the current trends and try to create a better product from the existing variety superior in terms of health, availability of nutrients, convenience, and so on. Dairy foods are an integral part of our routine meals. Hence, it is obvious that improvement in these food products will benefit us, especially for securing nutrient security and leading a healthy lifestyle.
Modification of lactose
Lactose is the primary carbohydrate present in milk and milk products. It can be absorbed by the human body only after enzymatic hydrolysis to the component monosaccharides viz., glucose and galactose by enzyme ß–galactosidase. Lactose intolerance is caused due to inability of the body to produce ß–galactosidase. Moreover, milk provides much of the calcium needed to maintain bone health. Therefore, ‘lactose intolerance’ can also be linked to age related osteoporosis. For people suffering from this ailment, milk as well as dairy products have been developed by complete or partial hydrolysis of lactose present in milk.
Lactose hydrolysed UHT milk (lactose-free milk) has been recently launched by AmulFed Dairy having < 0.01% lactose. Fermentation of milk leads to reduction in lactose. Fermented products like yoghurt and few varieties of cheese can be consumed by lactose-intolerant people, since lactose has been nearly fermented. Acid coagulated dairy products like paneer and chhana, are also nearly safe for such persons. Lactose-intolerance is quite prevalent in eastern India. Lactose-free ice cream is a novelty in Western countries and also being marketed by Amul in India. Lactose-free ice cream like products can be made from non-dairy sources like soya milk or coconut milk.
Modification of ß-lactoglobulin
It has been observed that milk has a potential to trigger allergic reactions in infants. ß-lactoglobulin, one of the major whey proteins found in milk, is believed to be the reason behind such milk allergy. Biotechnology can be instrumental in removing this fraction of whey protein from bovine milk. Elimination of ß-lactoglobulin is unlikely to cause any detrimental effects on consumers. This may help to curb several allergy occurrences worldwide.
A specific protein in milk, ß-lactoglobulin is able to initiate an allergy only when being devoid of iron (referred to as ‘empty milk protein’). The body’s immune system attacks milk proteins with its own IgE antibodies. The formation of Th2 lymphocytes is initiated in individuals who are allergic to this protein. The empty milk protein helps to activate Th2 lymphocytes. Th2 lymphocytes contribute to the production of IgE antibodies to milk proteins, developing an allergic reaction to milk. Such an allergy may cause swelling of the mouth and mucous membranes, diarrhoea, exacerbation of neurodermitis and in rare cases an allergic shock. Such protein when loaded with iron, is harmless. Scientists are researching on the mechanism by which such loading of protein with iron takes place to avoid allergenicity. The main processing technologies that have been used to prevent and eliminate cow’s milk allergy includes heat treatment, glycation reaction, high pressure treatment (100-300 MPa), enzymatic hydrolysis and lactic acid fermentation. Use of high pressure during hydrolysis of milk proteins may also be an efficient strategy for producing hypoallergenic whey hydrolysates.
Reduction in the fat content of milk and dairy products
Several chronic diseases like Cardiovascular Disease (CVD), obesity and certain forms of cancer in humans is linked to high consumption of fat. Experts recommend a total fat intake of < 30% of total daily calories. These dietary recommendations are one reason for the increasing demand for launching ‘lower-fat’ food products.
Using commercially available fat mimics/replacers products like low-fat versions of ice cream, cultured products, cheese, processed cheese, fat spreads have been successfully developed. Some research has also been done to introduce low-fat variants of traditional dairy products like Paneer and Burfi.
Cholesterol-reduced dairy products
Dairy products are considered to possess significant amount of cholesterol. To develop low-cholesterol dairy products, a number of processes have been developed viz. steam stripping, molecular distillation, solvent or super-critical extraction, reaction with cyclic anhydride, enzymatic method and treatments with adsorbents like ß–cyclodextrin, saponin, and activated charcoal. Super critical Fluid Extraction (SFE) with CO2 has also paved way in this direction. The combined extraction/adsorption operation resulted in the removal of > 97% of the cholesterol from butter oil. Research on cholesterol extraction is mainly limited to fat-rich products like Anhydrous Milk Fat and butter oil.
Eating foods low in saturated fat and cholesterol and high in phytosterols leads to reduction in LDL cholesterol. Plant sterols can be used to formulate low-cholesterol products. They can be incorporated into fat-rich dairy foods to enhance their nutritional profile, without compromising on their texture and taste.
Salt reduction in dairy foods
The 2005 Dietary Guidelines for America recommend that adults limit consumption of sodium to < 2300 mg/d. Excessive consumption of salt (i.e. sodium content) can cause many health problems in the human body. High blood pressure, heart attack, stroke are the common outcomes of excessive salt consumption. Efforts are being made to promote low-sodium dairy products in light of the proven health benefits.
For labelling a product as ‘reduced sodium’ cheese, at least 25% reduction of sodium when compared to its conventional counterpart is necessary. For Cheddar cheese, this would mean a reduction in sodium from 310 mg/50 g to 232 mg/50 g. Typical sodium content of processed cheeses (processed cheese, processed cheese food and processed cheese spread) range from 325 to 798 mg/50 g cheese. Therefore, a ‘reduced-sodium processed cheese’ should have a maximum of 244 to 600 mg/50 g of Na and a ‘low-sodium processed cheese’ will have = 140 mg/50 g of Na.
The three major ingredients that contribute to sodium in processed cheese are sodium-based emulsifying salts (~ 44-48%), natural cheese (~28-37%), and added salt (NaCl ~15-24%). There are two general means to control the amount of sodium in cheese. One is simply to restrict the addition of sodium chloride. The other is to use salt substitutes that contain little or no sodium but that give a taste similar to sodium chloride. Potassium chloride (KCl) is the most obvious choice for NaCl replacement. KCl must be included on the label (as mg of potassium per serving).
Cheddar cheese with a salt content of as low as 0.73% has been found to be acceptable. This is a major decrease from the procedurally accepted salt content of 2%. Partial replacement of NaCl with KCl was found to work for Feta cheese. Replacement of sodium chloride could be carried out at levels up to 50%. This technique has been found to apply for the creaming mixture in cottage cheese processing also. More work should be directed in reducing sodium content of processed cheese and processed cheese spreads, since over and above common salt, the emulsifying salts (i.e. sodium salts of citrates and/or phosphates) permitted by Food Safety and Standards Act (FSSA) up to maximum of 4.0% level, adds to the sodium content in such dairy food.
Dietetic dairy foods
The dairy industry has recently started paying attention to health-conscious consumers who demand low calorie foods. As a result, a large number of dairy products made with low-calorie and non-nutritive sweeteners are visible in the market. Low calorie sweeteners have become sugar alternatives to replace sucrose, either partially or fully, in a wide variety of dairy products.
Most commonly used intense sweeteners include saccharin, sorbitol, aspartame, acesulfame – K, and sucralose. Traditional sweets made from dairy-based ingredients like khoa and chhana are very much in need of calorie reduction. Studies have been conducted on Lassi, Rasogolla, Gulab Jamun, Burfi, Kalakand and Kulfi in this regard.
Flavoured milk has been found to be acceptable, even with replacement of sugar with intense sweetener. Three relatively new novel commercial sweeteners viz., tagatose, erythritol and trehalose have been studied, along with maltitol and polydextrose. Supplementation of these sweeteners with sucralose has led to development of ‘diabetic ice cream’ too.
Fortification with dietary fibre
Milk and most dairy products lack dietary fibre. With the growing interest in dietary fibre and its health benefits, dairy products have been fortified dietary fibres from various sources viz., oats, fruit pomace or peels, inulin, and so on. Many varieties of yoghurt are available in the market, few of which have fruit pulp added to incorporate fibre. Cereals-based milk desserts like Kheer, Payasam, Firni and Dalia are other dairy food sources of dietary fibre in Indian diets. Recently, Dahi, Lassi and other dairy products have been fortified with fruits, inulin and resistant starch to give the benefits of dietary fibre. Technology of developing low-fat Paneer using soy fibre and inulin has been successfully attempted. Amul has launched a new variety of Isabgol-enriched ice cream.
Vitamin and mineral modification in dairy products
Milk is considered to be an almost complete food. To make up for the nutrients that are absent, fortification of vitamins and minerals has been adopted by the dairy industry.
Liquid milk fortification with vitamins A and D is mandatory in several countries. ß-carotene (a precursor of Vitamin A) is added as a colour-enhancing agent to some milk products such as butter. Dried milk is often fortified with vitamins A and D, calcium, and iron. Milk-based infant formula and weaning foods are fortified with a range of vitamins, minerals, and other nutrients such as polyunsaturated fatty acids (PUFA) to make it resemble human milk as closely as possible.
Selection of an appropriate mineral fortificant (iron, calcium, etc.) is based on its organoleptic considerations, bioavailability, cost and safety. In the case of iron fortification, undesirable interactions with the food matrix can be avoided by coating the fortificant with hydrogenated oils or ethyl cellulose.
An important mineral for fortification of milk and milk products is calcium. Several commercial calcium salts are available for calcium fortification that includes carbonate, phosphate, citrate, lactate and gluconate. Milk and milk products can also be fortified with a range of other mineral salts such as magnesium, phosphorus, zinc, copper and manganese.
The microflora of dairy foods can also be modified in order to reap maximum health benefits in the most natural way possible. Probiotics can be defined as “live micro-organisms which when administered in adequate amounts confer a health benefit on the host.” A product can be labelled as a ‘pro-biotic’ if it contains at least 109 cfu/ml or g of product. Most common probiotics belong to the genus Bifidobacterium and Lactobacillus.
There are a variety of fermented milks available throughout the world. Some of the well-known products are Yakult, Acidophilus milk, Bifighurt, and Femilact. Probiotic milks offer health benefits such as improved intestinal health, managing cardiovascular disease, reducing levels of LDL, and enhanced immunity.
Geriatric dairy foods
Healthy wholesome food is as important to the elderly as it is to infants and kids in their developmental years. Deficiency of nutrients has been linked to a plethora of health issues in the elderly. To address these problems, it becomes important to regulate the diet of this group of population. As far as dairy products are concerned, the most important product is vitamin D enriched milk. Milk will also supply calcium to the body for stronger bones.
Whey Protein Isolates (WPI) are an important aspect of the geriatric diet. WPI provides immunological benefits. Lactoferrin present in WPI provides antioxidant properties. Such food ingredient helps in modulating body weight and also in tissue recovery post-surgery. Regulation of intestinal micro-flora is also necessary. Probiotic fermented milks will help in keeping the gut healthy.
Consumer awareness has led to scientific research that unearths several potential health benefits from food components. These researches help in developing foods with modified ingredients that can be consumed by everyone on a regular basis. These foods may not be medicinal but are proven to provide long-term improved health.
Further systematic scientific validation will lead to introduction of such foods to developing countries where the actual requirement lies. The disjoint between research and implementation in this field can only then be removed.