B. Surendra Nath

Rapid screening test for detection of oxytetracycline residues in milk using lateral flow assay.

A rapid, semi-quantitative lateral flow assay (LFA) was developed to screen the oxytetracycline (OTC) antibiotics residues in milk samples. In this study a competitive immuno-assay format was established. Colloidal gold nano-particles (GNP) were prepared and used as labelling material in LFA. Polyclonal antibodies were generated against OTC molecule (anti-OTC), purified and the quality was assessed by enzyme linked immuno sorbet assay. For the first time membrane components required for LFA in milk system was optimized. GNP and anti-OTC stable conjugate preparation method was standardized, and then these components were placed over the conjugate pad. OTC coupled with carrier protein was placed on test line; species specific secondary antibodies were placed on the control line of the membrane matrix. Assay was validated by spiking OTC to antibiotic free milk samples and results could be accomplished within 5min. without need of any equipment. The visual detection limit was 30ppb.

Effect of flaxseed oil and flour on sensory, physicochemical and fatty acid profile of the fruit yoghurt

The objective of this study was to incorporate flaxseed oil, flaxseed flour and fruits for the preparation of fruit yoghurt and analysed for their sensory, physicochemical and fatty acid profile. Overall acceptability of sensory scores indicates that fruit yoghurt (20% fruit and sugar mixture) with incorporation of flaxseed oil up to 2% and flaxseed flour up to 1% in combination can be used for preparation of fruit yoghurt with acceptable sensory attributes. The scores drastically reduced for yoghurt samples wherein 2% flaxseed flour was incorporated. The mixture of sugar and fruits diluted the milk composition and resulted in lower values in the fruit yoghurts. The increase in fat, protein, carbohydrate, minerals content in the yoghurt was mainly contributed by the flaxseed oil and flour. The addition of flaxseed oil did not show any affect on the water activity of the yoghurt samples. The yoghurt had dietary fiber content of 1.24%. The fresh control fruit yoghurt showed the acidity value of 0.88% LA, while the corresponding value for experimental samples varied between 0.85 and 0.88% LA. TBA values increased with increased incorporation of flaxseed oil and flaxseed flour. The fatty acid analysis revealed that alpha linolenic acid (ALA) content increased from 0.45% of ALA in control sample to 22.80% of ALA in the final product.

Effect of fortification of milk with omega‐3 fatty acids, phytosterols and soluble fibre on the sensory, physicochemical and microbiological properties of milk

BACKGROUND The effect of the addition of flaxseed oil (FO), phytosterols (PS) and polydextrose (PDX) on the physicochemical and sensory properties of milk was investigated, as they are known to impart health benefits. RESULTS For incorporating PS, a hydrophobic substance, FO and milk fat (MF) as an oil source, an emulsifier (DATEM) and PDX solution as an aqueous medium were used for the preparation of emulsion. Three emulsion formulations A (8 g PS, 8 g FO, 20 g PDX, 6 g MF), B (10 g PS, 10 g FO, 20 g PDX, 4 g MF) and C (12 g PS, 12 g FO, 20 g PDX, 2 g MF) were prepared and added individually to milk at a level of 50 g kg-1 . Based on sensory evaluation, formulation B was selected for fortification of milk. The fortified milk kept well at refrigerated temperature for 1 week, and changes in sensory, physicochemical and microbiological properties were comparable to those of control milk. The level of fortificants did not decrease in the milk after 1 week of storage. CONCLUSION An emulsion containing FO, PS and PDX could successfully serve as a potential delivery system for enhancing the nutritional and therapeutic potential of milk.