Development of a thin layer chromatography-based method to detect sorbitol presence in milk and its applicability in formalin preserved milk samples.

Sorbitol has been the new and emerging adulterant in dairy industry. The main aim of the study was to develop a method to detect sorbitol in milk, which is not affected by other sugars, polyols and formalin. Hence, a thin layer chromatographic (TLC) method was standardized to detect the sorbitol in milk. In the study 90 s duration for the impregnation of Silica gel 60F TLC plates with Cu- ions was found suitable to resolve sorbitol as a distinct spot. The standardized conditions were (1) developing solvent system consisting of n-propanol: ethyl acetate: water (7:1:2), (2) 0.5% of potassium permanganate in 0.1 M NaOH as color developing reagent. (3) Drying temperature (65°C/ 10 min.) after spraying the color developing reagent. The limit of detection was 0.2% of added sorbitol in milk. The standardized method could also detect the sorbitol in the presence of sucrose, glucose and polyols like mannitol and maltitol. In both cow and buffalo milk samples the standardized methodology performed well in detection of sorbitol. The method also performed well in sorbitol spiked formalin preserved milk samples. This method can be an alternative to the other methods involving costly equipment in detecting adulteration of milk with sorbitol.

A study on incorporation of giloy (Tinosporacordifolia) for the development of shelf-stable goat milk based functional beverage.

Goat milk has achieved significant place in human diet owing to its enormous therapeutic properties. There exists a scope of value-addition of goat milk to potentiate its health benefits by incorporating herbs and plants. Giloy (Tinospora cordifolia), a traditional medicinal plant with rich bioactive composition, can enhance the bioactive properties and shelf-life of goat milk. To this end, a study was conducted to develop shelf-stable giloy-goat milk beverage (GGB) by adding debittered giloy juice to goat milk (GM) and analyse the detailed product profile including proximate composition, bioactive properties, sensory, rheological, and structural characterisation. GGB resulted in two-fold increase (P < 0.05) in antioxidant activity and total phenolic content, thus enhancing the bioactive properties of the beverage as compared to GM. Further, increase in the particle size of GGB was observed along with components interaction, which was confirmed by FTIR, scanning electron and fluorescent microscopy. Storage stability studies indicated that bioactive properties of GGB remained unaffected (P > 0.05) by the sterilization process up to 90 days and sensory characteristics were not compromised till 105 days of storage. Therefore, the developed GGB is considered to be a shelf-stable beverage that retains its bioactive and sensory properties even after sterilization, making it a promising functional dairy product.

Eggnog: process optimization and characterization of a dairy-based beverage.

Eggnog, a dairy-based beverage, comprises both milk and egg proteins. We aimed at optimizing the eggnog formulation using Box-Behnken design of response surface methodology. The combined effects of milk (60-75), cream (25-35) and eggnog base (6-8, all three as g 100/ml) were investigated on heat coagulation time, viscosity and thermal gelation temperature. ANOVA indicated that experimental data were well explained by a quadratic model with high check values (R2 > 0.94) and non-significant lack of fit tests. Based on the responses, an optimized formulation of eggnog with 60.0 milk, 25.0 cream and 6.50 eggnog base (as g 100/ml), could be considered best for manufacturing eggnog with desired attributes. This optimized formulation was characterized for physico-chemical, microbial and sensory attributes and the results indicated significantly higher fat and protein content than control formulation, but lesser lactose and total sugar content. Significantly higher viscosity, heat stability and lower thermal gelation temperature were also observed for the optimized formulation. Coliform, yeast and mold, E. coli and Salmonella counts were not detected in any sample but a significantly lower total plate count was observed for the optimized formulation.

Effect of process parameters on the ß-galactosidase hydrolysis of lactose and galactooligosaccharide formation in concentrated skim milk.

The study aimed at evaluation of ß-galactosidase activity for lactose hydrolysis (DH) and galactooligosaccharide (GOS) formation at 7 °C. ß-galactosidase derived from K. lactis was more effective than B. lichenformis for DH and GOS formation in 16% lactose solution. ß-galactosidase from K. lactis exhibited 96.61% DH and 7.28% GOS production after 12 h of reaction and hence was utilized for lactose hydrolysis in concentrated skim milk (40% total solids). Use of 9.53 U/mL enzyme resulted in significantly high DH (97.06%) after 12 h with 4.90 g/L of residual lactose. However, maximum GOS formation of 12.01% with 94.74% DH was obtained after 4 h. Further increase in reaction time up to 12 h resulted in breakdown of tri and tetrasaccharide GOS, thereby, reducing GOS content. Hence, reaction time of 12 h was finalized to obtain maximum DH along with additional benefit of GOS formation.

Effect of pH and Heat Treatment on the Antioxidant Activity of Egg White Protein-Derived Peptides after Simulated In-Vitro Gastrointestinal Digestion.

The study aimed to analyze pH and heat treatment's effect in modulating the release of peptides with antioxidant activity after simulated gastrointestinal (GI) digestion of Egg white powder (EWP). EWP samples with neutral (EWPN) and alkaline (EWPA) pH were heat-treated at 20, 60, and 90 °C and analyzed for protein aggregation, solubility, and GI digestibility. Heat treatment decreased solubility and induced protein aggregation, which was higher for EWPN as compared to EWPA. The unfolding of EWPA proteins at 60 °C exhibited a higher GI digestibility and antioxidant activity via Oxygen Radical Absorbance Capacity (ORAC) assay as compared to EWPN. Interestingly, a reverse trend was observed in the cellular antioxidant assay, and the GI-digest of EWPN exhibited a higher antioxidant activity. The LC-MS/MS analysis are in concordance with cellular antioxidant activity assay and showed a higher intensity for peptides with potential antioxidant activity in the GI-digest of EWPN. The results indicate that heat treatment but not the pH is a critical factor in improving the protein digestibility and releasing peptides with antioxidant activity after GI digestion.

Impact of sequential enzymatic hydrolysis on antioxidant activity and peptide profile of casein hydrolysate.

ABSTRACT: This paper shows the potential of dual enzyme approach on antioxidant activity of casein hydrolysates. Casein was hydrolysed using the proteolytic enzymes alcalase, flavourzyme in isolation and in sequential order. Casein hydrolysates were evaluated for the degree of hydrolysis, antioxidant activity, molecular weight distribution patterns and peptide sequence. Casein hydrolysate produced by the sequential hydrolysis of alcalase and flavourzyme showed higher degree of hydrolysis and antioxidant activity as compared to hydrolysate obtained by individual enzymes. In size exclusion chromatograph of casein hydrolysate S3, peptides with molecular weight of 0.57 kDa share 12% area in total area of chromatogram which was 10 times higher than that of hydrolysate S1 and nearly half of that of hydrolysate S2. On subjecting to HPLC-TOF-ESI separation potential antioxidant peptides were identified. The peptide sequence VLPVPQ along with potential fragments was identified in hydrolysate S1 and S2 and HPHPHLS along with its potential sequence was identified in hydrolysate S1, S2 and S3. Sequential hydrolysis of casein showed better antioxidant activity and peptide profile in less duration as compared to the casein hydrolysate obtained by individual enzyme.

A novel approach to detect highly manipulated fat adulterant as Reichert-Meissl value-adjuster in ghee (clarified butter) through signature peaks by gas chromatography of triglycerides.

Ghee, the clarified butter fat being the costliest fat among other edible oils and fats in India, prone to adulteration with highly manipulated cheaper oils/fats, especially during lean season. The present investigation carried on triglycerides profile of one of the latest components of the adulterant fat i.e. RM (Reichert-Meissl)-adjuster, has been exploited to check the adulteration of ghee with a newly emerged highly manipulated fat. Using standardized (S)-limits specified by the ISO/IDF for cow milk fat, the minimum level of detection of the adulterant fat was observed as 7.5%. However, in case of buffalo ghee, due to non-availability of the ISO/IDF limits, the detection of this adulterant fat in buffalo ghee was not possible. Gas chromatograms showed specific signature peaks of large size in the retention time region of 4.5 to 6.5 min for RM-adjuster and adulterant fat, whereas no such peaks were observed in pure cow and buffalo ghee samples. The new approach of zooming in and superimposing of selected peaks in the chromatograms of triglycerides of suspected ghee has been used as a strategy to find adulterant fat's presence. Through this approach, the addition of RM-adjusted highly manipulated foreign fat (adulterant fat) to the tune of even 0.5% could be achieved in both cow as well as buffalo ghee.

Encapsulation of antioxidant peptide enriched casein hydrolysate using maltodextrin-gum arabic blend.

Antioxidant peptide enriched casein hydrolysate (AO-CH) are receiving increasing attention due to their potential as functional ingredient. Encapsulation of AO-CH using maltodextrin-gum arabic (MD/GA) as wall material could represent an attractive approach to overcome the problems related to their direct application. Encapsulation parameter were optimized using different ratio of core to coat and proportion of coating material (10:0, 8:2, 6:4) under varying pH (2-8) for encapsulation efficiency (EE).The preparation P3 resulted in maximum EE (87%) using core to coat ratio 1:20, at pH 6.0 with 8:2 MD/GA ratio. The encapsulated preparation showed reduced bitterness (p < 0.05) compared to the casein hydrolysate together with maximum retention of antioxidant activity (93%). Further, the narrow range of particle size, indicates their better stability and represents a promising food additive for incorporation in food.

Direct estimation of sialic acid in milk and milk products by fluorimetry and its application in detection of sweet whey adulteration in milk.

Sialic acid, being a biologically active compound, is recognised as an important component of milk and milk products. Almost all the sialic acid estimation protocols in milk require prior hydrolysis step to release the bound sialic acid followed by its estimation. The objective of this work was to estimate sialic acid in milk and milk products by fluorimetric assay which does not require a prior hydrolysis step thus decreasing the estimation time. The recovery of added sialic acid in milk was 91·6 to 95·8%. Sialic acid in milk was found to be dependent on cattle breed and was in the range of 1·68-3·93 g/kg (dry matter basis). The assay was further extended to detect adulteration of milk with sweet whey which is based on the detection of glycomacropeptide (GMP) bound sialic acid in adulterated milk. GMP is the C-terminal part of κ-casein which is released into the whey during cheese making. For detection of adulteration, selective precipitation of GMP was done using trichloroacetic acid (TCA). TCA concentration in milk was first raised to 5% to precipitate milk proteins, especially κ-casein, followed by raising the TCA concentration to 14% to precipitate out GMP. In the precipitates GMP bound sialic acid was estimated using fluorimetric method and the fluorescence intensity was found to be directly proportional to the level of sweet whey in adulterated milk samples. The method was found to detect the presence of 5% sweet whey in milk.