PHYSICO-CHEMICAL AND STORAGE CHARACTERISTICS OF MILK CHOCOLATES DEVELOPED FROM BUFFALO MILK, TABLE BUTTER AND ROASTED GROUNDNUTS
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Date
1996
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AAU, Anand
Abstract
This study was undertaken to develop a simple process to manufacture milk chocolates by panning of batch method on the process based to manufacture caramel. Roasted groundnuts were added to ascertain economical viability of the product as well as to increase the protein content without adding any preservative, hydrogenated fat or cocoa butter. It was also planned to evaluate the impact of various ingredients on the composition, physicochemical, organoleptic and storage characteristics of the milk chocolates and thereby to suggest a simple process for manufacture of acceptable milk chocolates with a small but reasonable shelf life. Raw groundnut kernels were roasted in tray in an air-oven maintained at 150 + 10 °C for 15 min. After this treatment, the skin and hearts were removed manually and the skin free and heart free cotyledons were cut into small pieces manually. For the preparation of golden syrup, concentrated hydrochloric acid was added at the rate of 1 per cent to a sugar solution (67° brix) and the solution was heated to 85°C for 40 min. After cooling the pH of the solution was adjusted to 7.00 by using sodium bicabonate. Milk chocolates were prepared by using buffalo milk as base and other ingredients such as roasted groundnuts/ sugar, golden syrup/ table butter/ cocoa powder/ glycerol mono-stearate/ shellac and tri-sodium orthophosphates were incorporated in the formulation of four types of recipe to manufacture four types of milk chocolates namely CT-1/ CT-2/ CT-3 and CT-4. The' milk chocolate type/ CT-1, contained 15 g table butter and 75 g roasted groundnuts per batch. Type CT-2 contained 25 g table butter and 50 g roasted groundnuts whereas CT-3 contained 20 g table butter and 60 g roasted groundnuts. The recipe of CT-4 consisted of 10 g table butter and 100 g roasted groundnuts. In addition to these two ingredients, all the four types of milk chocolates consisted of equal amount of rest of the ingredients per batch. Milk chocolates were manufactured by adding various ingredients to the buffalo milk taken in a pan. The contents of the pan was stirred at a temperature 90-95°C till a viscous mass was obtained. This viscous mass was transferred to a tray to harden and after hardening/ it was cut into small pieces and wrapped in aluminium foil. These small pieces of milk chocolates were transferred to plastic boxes. Four such trials were conducted and the product were stored at 27-30°C as well as 4-8°C under a domestic refrigerator. The major ingredients were analyzed for their proximate chemical composition and the milk chocolates were analysed for their compositional, rheological properties/ organoleptic characteristics and chemical changes occurring during storage for a period of 60 days. The roasted groundnuts contained 45.88 per cent oil/ 26.21 per cent protein, 2.90 per cent moisture, 2.10 per cent ash and 22.91 per cent total carbohydrates. The cocoa-powder used possessed 14.58 per cent fat and 6.00 per cent moisture. The table butter was found to contain 83.70 per cent fat and 16.73 per cent moisture. The golden syrup was found to contain 60 per cent sucrose and total solids 69°brix. The yield of the four types of milk chocolates CT-1, CT-2, CT-3 and CT-4 were 384.66, 371.05, 371.16 and 388.55 g per kg of the ingredients used. The chemical composition of the four types of milk chocolates showed that CT-1, CT-2, CT-3 and CT-4 on an average contained moisture 9.63, 9.84, 6.92 and 7.49 per cent; total fat 31.06, 31.84, 29.87 and 32.69 per cent; total protein 11.72, 11.38, 11.84 and 12.54 per cent; sugar (sucrose) 48.18, 49.56, 52.76 and 49.93 per cent; total ash 0.88, 0.99, 0.98 and 0.96 per cent; sodium 179.28, 177.39, 196.10 and 147.81 mg per 100 g; calorific value 4295.36, 4117.18, 4099.21 and 4327.13 calories per g and soluble matter 66.90, 60.72, 61.64 and 56.37 per cent respectively. The rheological characteristics of CT-1, CT-2, CT-3 and CT-4 were hardness, 15.82, 15.52, 22.47 and 17.76 kg; brittleness, 4.11, 4.80, 5.02 and 2.91 kg; cohesiveness, 0.030, 0.038, 0.029 and 0.034; springiness, 1.62, 2.06, 1.75 and 1.87 mni; gumminess/ 47.12, 60.73, 65.81 and 55.45 kg and chewiness, Q.11, 1.41, 1.13 and 1.05 kg mm respectively. The physico-cheroical changes namely status of moisture, pH, free fatty acids and peroxide value were evaluated in fresh and during storage at various intervals for a period of 60 days at two different storage conditions i.e., at 27-30°C and at 4-8°C under a domestic refrigerator. The initial levels of moisture in CT-1, CT-2, CT-3 and CT-4 milk chocolates was 7.85, 8.02, 5.63 and 6.09 per cent respectively which on 60 days storage changed to 5.97, 6.43, 7.07 and 7.33 per cent respectively. The milk chocolates stored at 4-8°C for a period of 60 days showed the moisture content to be 5.87, 7.55, 5.60 and 5.91 for CT-1, CT-2, CT-3 and CT-4 respectively. The pH values of CT-1, CT-2, CT-3 and CT-4 milk chocolates were 7.02, 6.87, 6.79 and 6.78 initially which on storage at 27-30°C dropped to 6.86, 6.75, 6.76 and 6.76 respectively while those stored at 4-8°C increased to 7.09, 6.97, 6.87 and 6.96 respectively. The free fatty acids content (as per cent oleic acid) of CT-1, CT-2, CT-3 and CT-4 milk chocolates were 0.08, 0.08, 0.10 and 0.09 initially which increased to 0.16, 0.17, 0.14 and 0.18 on 60 days storage at 27-30°C while those stored at 4-8°C increased to 0.11, 0.09, 0.11 and 0.10 respectively after a storage period of 60 days. The peroxide content (milliequivalent per kg of sample) was initially 1.50, 1.00, 3.50 and 3.00 which increased to 9.50, 2.50, 6.00 and 5.00 for milk chocolates stored at 27-30°C and 5.50, 5.50, 6.50 and 6.00 for milk chocolates stored at 4-8 C after a storage period of 60 days for CT-1, CT-2, CT-3 and CT-4 respectively. The sensory quality of different types of milk chocolates wno evaluated for colour, flavour and texture as affected due to storage. The effect of treatment as well as effect of storage period on colour score was found to be non-significant (P <0.05) under both conditions of storage. The flavour score was decreased but the effect of treatment and storage period were nonsignificant (P < 0.05) under both storage conditions. Milk chocolate types, CT-2 and CT-4, were unacceptable after a storage period of 60 days at 27-30°C from flavour point of view. The effect of treatment and storage period on texture score was nonsignificant (P <0.05) under both storage conditions. Milk chocolates type, CT-2, and CT-3, was unacceptable with respect to texture after a storage period of 60 days at 27-30°C.
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DAIRY CHEMISTRY, DAIRYING, A STUDY