Impact of pulsed electric field treated milk on quality of paneer and khoa.

The present work was undertaken to investigate the feasibility of pre-treatment of raw milk with Pulse Electric Field (PEF) treatment before its entry into the processing chain. A custom-designed and fabricated PEF applicator was used for the non-thermal treatment protocol. Raw milk was treated under three treatment protocols, viz., conventionally heat treatment (CHT), PEF treated milk subjected to conventional heat treatment (PT-CHT) and PEF treatment (PT). For the PT protocol, milk was subjected to high voltage (55 kV) square wave of pulse width 900 µs, for 100 s at a frequency of 90 Hz. The treated milk was then converted to two popular products, namely and paneer and khoa, which were evaluated for its physico-chemical, microbiological, sensory quality and shelf stability. Since khoa is a heat desiccated product, it was evaluated only against PT-CHT and CHT treatments. It was observed that PT treatment resulted in paneer with softer body with higher whiteness index, compared to other experimental samples. The PT treatment did not affect the product acceptability and the product had a shelf stability of 12 days under refrigeration, as against 16 days for CHT and PT-CHT treatment. The treatment protocols for milk did not significantly affect the quality and shelf life of khoa. Thus, there is wide future scope to used pulsed electric fields treatment synergistically with conventional heat treatment for inactivation of microorganisms, with better retention of nutritional and physical properties of product which has potential to save considerable amount of energy and time during processing of product.

Quality attributes of dahi prepared from milk fortified with omega-3 fatty acids, phytosterols and polydetxrose.

In the present study, dahi prepared using milk fortified with omega-3 fatty acids (flaxseed oil), phytosterols and soluble fibre (polydextrose) through an oil-in-water emulsion was evaluated for the physico-chemical and sensory quality. The levels of fortificants in fortified dahi were also estimated. Fortification process did not affect the degree of fermentation in terms of pH and acidity. Sensory scores of fortified and control dahi did not differ significantly. Fortified dahi had lower viscosity, firmness and consistency, and higher water holding capacity (WHC) compared to control; however, significant differences were not observed in firmness and consistency values. Storage study indicated that pH, acidity, %WHC, firmness and consistency values and lactic acid bacterial counts did not differ significantly throughout storage period in both the dahi samples and recorded good sensory acceptability during storage. Fortified dahi provides 282.53 mg, 415.92 mg and 1.019 g of α-linolenic acid, total phytosterols and polydextrose, respectively per 100 g of product. Moreover, no loss in the initial content of ALA, phytosterols and polydextrose had occurred after 8 days of storage period. The present study suggests the feasibility of adding flaxseed oil, phytosterols and polydextrose as functional ingredients in the form of water soluble emulsion to milk, which could be converted to dahi with acceptable properties and enhanced nutritional and therapeutic potency.

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.

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.

Genetic characterisation of microsporidia infecting Indian tasar silkworm, Antheraea mylitta, using morphology and molecular tools.

The utility of inter simple sequence repeat-PCR (ISSR-PCR) assay in the genetic characterisation and elucidation of the phylogenetic relationship of different microsporidian isolates infecting tropical tasar silkworm, Antheraea mylitta Drury, is demonstrated. A total of 22 different microsporidians collected from the diseased tasar silkworms from Jharkhand state of India were analysed using morphological characters and ISSR-PCR. Observations spores under phase contrast microscope revealed oval to elongate in shape with length ranging from 3.8 µm to 5.1 µm and width from 2.6 µm to 3.3 µm. All the microsporidian isolates except MIJ-1gC showed gonadal infection and transovarial transmission in infected tasar silkworms. Fourteen out of 20 ISSR primers tested generated reproducible profiles and yielded a total of 281 fragments, of which 273 were polymorphic (97%). The degree of banding pattern was used to evaluate genetic distances and for phylogenetic analysis. The results demonstrated that ISSR analysis may be a useful and efficient tool for taxonomical grouping and phylogenetic classification of different microsporidians in general.

Toxic impact of organophosphorus insecticides on acetylcholinesterase activity in the silkworm, Bombyx mori L.

The effect of widely used commercial-grade organophosphorus insecticides, namely, fenitrothion and ethion, on acetylcholinesterase activity and acetylcholine levels in brain, fat body, and silk gland of Bombyx mori on Days 1, 3, and 5 and food intake of the fifth instar were studied. Acetylcholinesterase activity was found to be inhibited, followed by a concomitant increase in acetylcholine levels in the target tissues. These changes suggest an acceleration in energy metabolism of nerve cells, leading to death of the insects. Food consumption during the fifth instar underwent a significant decrease at lethal doses and an insignificant increase at sublethal doses of fenitrothion and ethion. The overall changes observed in acetylcholinestease, acetylcholine, and food intake due to fenitrothion and ethion were, insecticidewise, in the order fenitrothion