RECENT ADVANCES IN THE DEVELOPMENT OF HERBAL BASED DAIRY FOODS

Herbs and their extracts have long been used for curing health related complications and metabolic disorders as natural remedies. Functional components present in them aids in performing a wide range of biological functionalities. A considerable portion of today’s functional food market consists of herbal supplemented functional foods. Dairy products, popular throughout the country, can be used effectively as carriers for herbs to satisfy the needs of health conscious consumers. However, depending upon the concentration and type, the incorporation of herbs into food products may have certain undesirable effects on their sensory, physico-chemical and textural properties which in turn could affect their overall acceptability. Presently, the herbal ghee being marketed globally is mostly sold as medicinal ghee, which is associated with typical flavour, bitter or pungent taste and a dark colour. Such therapeutic preparations are therefore not acceptable for routine use. Incorporation of these nutraceuticals into food systems may therefore call for technological modifications so that the sensory quality of the final product remains unaltered. Further, limited information is available for ascertaining the residual levels of these functional components in herbal food preparations. Effect of herbal and food constituents interactions on human health have to be studied thoroughly.


INTRODUCTION
Rapid urbanisation and industrialisation have produced advancement on the social and economic fronts in developing countries such as India which has resulted in dramatic lifestyle changes leading to lifestyle related diseases. Due to the appearance of several lifestyle related health disorders, there has been increasing interest in the study of functional foods supplemented with functional components or substances. Functional foods provide some health benefit beyond their nutritional value. Functional foods contain bioactive compounds which offer the health and wellness benefits that have been linked to functional foods. By 2024, the international functional food market is expected to reach a value of about $255.10 billion. Herbs have been used as food and medicine for centuries. A wide variety of active phytochemicals including the flavonoids, terpenoids, lignans, sulfides, polyphenols, carotenoids, coumarins, saponins, plant sterols, curcumins and phthalides have been identified in herbs. In the recent past, research interest has been focused on various herbs that possess hypolipidemic, antiplatelet, antitumor or immune stimulating properties that may be useful adjuncts in reducing the risk of cardiovascular diseases (CVD) and cancer (Hussain et al., 2015). Today, industry is showing a great deal of interest in utilising these herbal bioactives for functional foods manufacture. Ayurveda has mentioned several ways in which the medicinal benefits of herbs could be conveyed via certain foods as carriers. Milk is one of the most important of such carriers (Sawale et al., 2013b). In India, a significant amount of milk produced is utilised for traditional dairy products. Conversion of liquid milk into traditional dairy products not only preserves milk solids for longer time but also adds value to milk. Indian traditional dairy products have a huge demand and their domestic markets are well established. Incorporation of herbal bioactives into traditional Indian dairy products not only helps the industry to meet the growing consumer demand for these foods but also facilitates in competing with ever increasing world functional food market (Sawale et al., 2013a).

Butter and ghee
In India, about 39 per cent of the total milk produced is converted into ghee and butter. The clarified milk fat, particularly ghee, has the characteristics to absorb all the medicinal properties of the herbs with which it is fortified, without losing its own qualities. Exploiting this concept several medicated ghee preparations have been developed and about 5560 medicated ghee types are reported in Ayurvedic literatures and they have also been used in the treatment of various diseases. Herbs contain high amounts of phenolic compounds which possess great antioxidant properties. The natural antioxidant properties of herbs have made their use in the formulation of functional foods specifically targeted for the people suffering from CVD (Najgebauer Lejko et al., 2009). Presently, the herbal ghee being marketed in the global market is mostly sold as medicine (medicinal ghee). These products possess a typical flavour, a bitter or pungent taste and a dark colour. Such therapeutic preparations are therefore not acceptable for regular consumption. At NDRI, Karnal, herbal ghee incorporating the functional attributes of Arjuna ghee has been developed for providing beneficial effects against CVD, and the product was more stable to oxidative deterioration as compared to conventional ghee. The consumer acceptability of this product was also very good (Rajanikant and Patil, 2005). Unlike in case of medicated ghee preparations, Arjuna ghee can be replaced with normal ghee in the daily diet. Also the antioxidant properties of herbs led their use into fat rich dairy products for retarding auto-oxidation there by prolonging the shelf-life. Moreover, increasing sensitivity of consumers to synthetic ingredients as well as the increasing awareness about the effect of diet on their health contributed to the increasing trend to use natural additives like herbal extracts for the stabilisation of fat rich dairy foods like ghee, butter oil, butter etc.
Sage (Salvia officinalis) and Rosemary (Rosmarinus officinalis) extracts are the most widely used for this purpose (Ozcan, 2003). These extracts have antioxidant activity many times stronger than synthetic antioxidants like BHA or BHT (Estévez et al., 2007). Some of the reported study's related to herbal ghee where the herb fortified ghee has shown good antioxidants activity as compared to ghee supplemented with synthetic antioxidant is depicted in Table 2.

Shrikhand
Shrikhand being a semisoft, sweetish-sour, whole milk product prepared from lactic fermented curd can easily harbour herbs/herbal extracts without undergoing significant changes in sensory quality. A study conducted by Landge et al. (2011) reported that addition of 0.5 per cent Ashwagandha powder to shrikhand has improved the organoleptic quality and the product was remained acceptable up to 52 days at refrigeration temperature.

Sandesh
Sandesh is a very popular heat desiccated product of coagulated milk protein mass called chhana. Incorporation of herbs such as turmeric (Curcuma longa L.), coriander (Coriandrum sativum L.), curry leaf (Murraya koenigii L.), spinach (Spinacia oleracea) and aonla (Emblica officinalis), separately as a paste, at the 10 per cent level into Sandesh improved its antioxidant properties. Herb coriander incorporation resulted in increased shelf-life of herbal sandesh up to eight days and 30 days when stored at 30±1°C and 7±1°C, respectively (Bandyopadhyay et al., 2007).

Aloe vera based dairy/food products
The aloe vera juice finds wide application in dairy/food products like production of ready to serve drink, health drink, soft drink, laxative drink, aloe vera lemon juice, sherbet, aloe sports drink with electrolyte, diet drink with soluble fibre, hangover drink with B vitamin, amino acids, healthy vegetable juice mix, tropical fruit juice with aloe vera, aloe vera yoghurts, aloe vera mix for whiskey and white bread, cucumber juice with aloe vera (Ahlawat and Khatkar, 2011). Aloe vera products are available in various forms like capsules, gel and juice. It has cooling effect and bitter in taste, it contains aloin that is responsible for its purgative action and well known for its therapeutic properties. It regulates the peristaltic movements of intestines and promotes digestion. Regular consumption of aloe vera juice on a daily basis brings about gradual and gentle health benefits, without irritant or harmful side effects. It also improves blood circulation due to its ability to detoxify. Some notable food products available in the markets are as under. Aloe Vera More than 200 that include antibiotics, pain inhibitors, burn healers (Hussain et al., 2009)

Aloe vera herbal ice creams
Aloe vera ice cream prepared with various ingredients to have the final ice cream should contain 10 % fat, 0.5 % stabilizer and emulsifiers, 36 % total solids and 15 % sugar. Various ingredients Viz. milk (buffalo milk), skim milk powder, butter and aloe vera added in such a way to obtain the final ice cream should contains minimum of 10 % milk fat and 36 % total solids. The inclusion of Aloe vera pulp at 20 % level had maximum score of 92.89. The bitter taste of the Aloe vera pulp had masked by the addition of the vanilla flavour and sugar. The production of this dairy herbal ice cream product is beneficial for diabetic patients with natural ingredients (Manoharan et al., 2012).

Aloe vera juice enriched lassi and dahi
Lassi, a ready to serve traditional fermented milk beverage has got wide popularity in India as well as in overseas markets. Sweet lassi with its characteristic sweet and slightly sour taste can be used as a food carrier for herbal bioactives like Aloe vera juice etc. At NDRI a functional lassi and dahi were developed by supplementing the herb Aloe vera (Aloe barbadensis Miller) and probiotics. Animal study of functional lassi revealed that it has better immunoprotective effects compared to control lassi. The authors have reported that Aloe vera supplementation has supported the growth of probiotic strain. The probiotic viability was more than 7 log cfu/ml during 12 days storage period (Hussain et al., In Press).

Aloe vera chocolate
The cocoa powder is mixed with skim milk powder. Sugar is dissolved in water till complete saturation in a boiling pan and the mixture is heated with occasional stirring. Aloe vera juice is then added to the mixture. Once the mixture attains 110 ºC, the cocoa powder and skimmed milk powder are added after then, butter and flavour are added. After 20 minutes the whole mass is poured into a frame on an oiled slab, and then it is cut into appropriate size and wrapped in waxed paper. Maximum sensory analysis of colour, taste, aroma and texture in the aloe vera chocolate production is obtained from ingredients at the optimized process conditions. The optimum condition for taste is sugar 1000 g, skim milk powder 1019 g, cocoa powder 252.5 g and aloe vera juice 82.5 ml. (Jayabalan and Karthikeyan, 2012).

Low-fat set aloe vera fortified probiotic yoghurt
The reconstituted skim milk for low-fat aloe vera fortified set yoghurt was prepared by using 16.57g skim milk powder in aloe vera juice and water blend, 25 and 75 ml respectively. The prepared reconstituted skim milk was heated or pasteurized properly at 82-85ºC for 12-15 min.  (Panesar et.al., 2011)

Aloe vera enriched flavour milk
Flavoured milk is a beverage in which sugar, flavouring and colouring agents are added and it contains all the constituents of milk. It is a good source of protein, carbohydrate and minerals. It provides energy and water to digest the food, regulate body temperature and prevent dehydration. Jothylingam and Pugazhenthi (2013) prepared the herbal aloe vera enriched flavour milk by incorporating aloe vera pulp extract at 5 % levels to flavoured milk. Further, dietetic herbal (Aloe vera enriched) flavoured milk up to 75 % replacement of sugar with aspartame and 100 % replacement of sugar with sucralose are concluded as the best based on the sensory evaluation.

Aloe vera gel enriched dahi
The milk (fat 3.6%, protein 3.2% and carbohydrate 4.6%) used for preparation of aloe vera enriched dahi. The homogenized milk was heated at 85-90ºC for 5 minutes and cooled to 45 ºC. Spray dried aloe vera gel powder was added at 0.15% level and then inoculated with 10% standard dahi starter (Hatsun brand, fat 3.1%, protein 3.3% and carbohydrate 4.4%). The inoculated milk was incubated at 45 ºC till the dahi was set (Ramachandran and Srividya, 2014). Aloe gel supplementation in the form of curd to be helpful in lowering the glycemic response to wheat based meal. It further indicates the potential of using Aloe gel as a hypoglycaemic ingredient in dairy products. Low glycemic foods incorporated Aloe gel nutraceuticals could also result in additional functional benefits.

CONCLUSION
Herbal nutraceuticals are natural substances with wide range of health attributes. In India, most of milk is converted into traditional dairy products which are consumed by people of all age groups. Traditional dairy products can act as potent carrier for the herbs which can add functional attributes to the product thereby improving consumers well being. However, several technological challenges have to be overcome to develop milk products enriched with herbs. Process modifications are needed to reduce the undesirable effects of herbs incorporation on palatability of foods. Research should be focussed to find out the effect of processing conditions on the bioavailability of functional components present in herbs. Knowledge of interactions of herbal and food constituents and their effect on human health has to be studied thoroughly. Scientific community must apply modern techniques to assure the efficacy and safety of herbs and their bioactive components for their safe use in food formulations.