Freshly prepared cow milk ghee and buffalo milk ghee were procured from the experiential learning unit of the division of Animal husbandry and Dairy Science of the Institute whereas, spray-dried skimmed milk powder (SMP) having 3.90 % moisture, 0.60 % fat, and 0.76 ml solubility index was purchased from Kolhapur Zilla Sahakari Dudh Utpadak Sangh Ltd. Kolhapur. Carrageenan – Type II iota-carrageenan (make Hi-media) was used as a stabilizer while glycerol was used as a plasticizer and purchased from Qualigens Chemical, Mumbai. To make effective emulsion, polyoxyethylene sorbitan monooleate (Tween-80) was used as an emulsifier which was procured from S. D. Fine chem. Ltd, Mumbai. Iodized salt (Tata), annatto butter color, and citric acid were also used as other minor ingredients. The Planetary mixer (SPAR Make, Taiwan) was used for blending two phases.
Rapid and slow; pre-cooling of ghee
Initially, cow milk and buffalo milk ghee were melted at 70 °C followed by rapid and slow pre-cooling to 20 °C in a controlled condition and then kept at 5 °C by quiescent storage under refrigeration. The stored ghee was evaluated at 30 °C for sensory character viz. texture, consistency and color on a 100-point scale. The treatments were as follows:
CG1: Cow milk ghee melted at 70 °C and rapidly pre-cooled to 20 °C
CG2: Cow milk ghee melted at 70 °C and slowly pre-cooled to 20 °C
BG1: Buffalo milk ghee melted at 70 °C and rapidly pre-cooled to 20 °C
BG2: Buffalo milk ghee melted at 70 °C and slowly pre-cooled to 20 °C
Preparation of low-fat spread using cow and buffalo milk ghee
As shown in Fig. 1., Patange (2005) devised a process for making low-fat spreads (LFS) from ghee made from cow and buffalo milk. Before blending and emulsifying, the fat and serum phases are prepared and tempered separately. The emulsifier was then added to the hot ghee. It was then heated to 70°C (in a water bath) and quickly cooled to 20°C (at a cooling rate of 12°C per minute) with continual agitation in a chilled water bath (2.5°C), and then to 5°C by quiescent storage in a refrigerator for an overnight duration. It was then held in the water bath for 6 h before usage to bring the fat phase back to a temperature of 251 °C. The aqueous phase was prepared by dissolving SMP in water with soluble components, boiling to 55 °C, filtering through a two-fold muslin cloth, pasteurizing at 72 °C for 15-20 seconds, and then cooling to 20 °C and storing overnight in the refrigerator. For final acidification and warming to blend temperature, this aqueous phase was treated with weak citric acid.
Flat beater attachment of planetary mixer was used for 30 sec at medium speed to whip the tempered fat phase into a creamy mixture. The serum phase was introduced in three equal parts. After each addition of serum phase, medium-speed blending was performed for 30 sec at a time. The 75 g of LFS was placed in plastic cups and sealed with lids before being stored in the refrigerator at 5 °C. The treatments were as follows:
CGS: LFS using cow milk ghee
BGS: LFS using buffalo milk ghee
Effect of colour and flavour on qualities of LFS
The effect of the addition of 0.1% of annatto color and 4 ppm of diacetyl flavor on LFS were evaluated for colour and flavour properties, respectively.
Effect of exposure time on sensory properties of LFS prepared from cow and buffalo milk ghee
Both LFS were removed from the refrigerator (5±1 °C) and evaluated for sensory qualities at the following coded intervals. During the evaluation period, the LFS were kept in the incubator maintained at 35±1°C.
CS1: Cow ghee LFS removed immediately from refrigeration
BS1: Buffalo ghee LFS removed immediately from refrigeration
CS2: Cow ghee LFS exposed for 10 min
BS2: Buffalo ghee LFS exposed for 10 min
CS3: Cow ghee LFS exposed for 20 min
BS3: Buffalo ghee LFS exposed for 20 min
CS4: Cow ghee LFS exposed for 30 min
BS4: Buffalo ghee LFS exposed for 30 min
The moisture content, sleep point (melting point), and iodine value of the ghee was determined by using FSSAI, 2015 methods whereas, fat, crude protein, carbohydrate, total ash, and TS content of LFS were determined as per AOAC (2000). The free fatty acid content of the LFS was estimated as per FSSAI (2015), whereas the pH of the spread was measured by pH meter (Lab India Instruments Pvt. Ltd., Mumbai) by inserting the electrode in the spread (sample temperature was maintained at 5±1 °C. The oiling off and wheying off in LFS was estimated as suggested by deMan and Wood (1958).
Sensory qualities of buffalo and cow ghee, which are commonly utilised in dairy products, were analysed using the method of sensory profile by a multidimensional approach (Patange 2005). After the ghee samples were found to be free of harmful microorganisms, sensory evaluations were carried out. Using a trained panel of five members (aged between 23 and 50 years old) in the sensory room, the evaluation was done out. Panelists were shown ghee samples in ceramic cups numbered with random two-digit codes sequentially under white fluorescent light. The panelists identified and selected the descriptors for establishing the sensory profile of ghee, and thereafter, the intensities of the descriptors were evaluated for colour (at 30±1°C) in a scale from 0 to 100 (where 0 = white and 100 = pronounced yellow), for texture (at 20±1°C) in a scale from 0 to 100 (where 0 = smooth pasty and 100 = Extremely large grain) and for consistency (at 20 ±1°C) in a scale from 0 to 100 (where 0 = Essentially fluid and 100 = hard solid). The acceptability of LFS was examined by the qualified panel of judges. Color and appearence, spreadability, body and texture, flavour, and overall acceptability were evaluated using a 9-point rating scale (Amerine et al. 1965). The spreadability of the product was examined by spreading LFS on pieces of bread at a consistent temperature 5±1°C.
Colour values for each sample were measured five times after the colorimeter was calibrated with black and white standards. The L* (lightness; 100=white, 0=black), a* (redness, red, green), and b* (yellowness, yellow, blue) values of samples were measured with a colour flex colorimeter.
The rheological properties of ghee and ghee-based low-fat spread were determined at 5ºC using texture analyzer model TAT2i (stable micro system, UK) provided with texture expert exceed software. The sample was carefully filled up in a cuboidal polypropylene tub (11.0*6.4*3.5cm) so that no air pockets remained within the sample. It was allowed to set at 5 ºC for an overnight period. The product was subjected to penetration to a depth 25.0 mm by a 300 PERSPEX CONE PROBE. The other test conditions included measuring force in compression mode, re-test period of 5.0 mm/sec, test speed of 2.5 mm/sec and post-test speed of 10 mm/sec. It was discovered that during penetration, the force increased up to the maximum depth of penetration, and this value was referred to as "hardness" (g), and accordingly the region beneath the penetration cycled (downstroke) in the force. Work of shear, or the 'energy expended in shearing,' was represented by a distance-curve (g.s). This resulted in an undesirable peak when the probe was removed from the sample and replaced with another one. The 'stickiness' (g), and the negative peak area was regarded as the 'work of adhesion' (g.s).
On all experimental data sets, a one–way analysis of variance was performed using SPSS 16 for windows (SPSS Inc. in Chicago, USA). In order to determine the significance of differences between means at a P<05 level, the Duncan analysis was used.