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Khamrui K.,National Dairy Research Institute | Solanki D.C.,Product and Process Development Group
International Journal of Dairy Technology | Year: 2010

The texture of sandesh an Indian milk-based sweetmeat, was characterised by instrumental means and interrelationships among textural parameters and composition were studied. Hardness, fracturability, chewiness and adhesiveness was highest for sandesh prepared from milk containing 6% fat, 9% SNF and lowest for sandesh prepared from milk containing 1.5% fat, 9% SNF. Hardness of sandesh was significantly positively (P < 0.01) correlated with the fat content but negatively (P < 0.01) correlated with moisture and ash. Moisture and fat had negative and positive correlation (P < 0.01) with fracturability, respectively. Ash and moisture had a positive (P < 0.01) influence on resilience whereas fat had a negative influence. Cohesiveness was not influenced by composition parameters. Springiness had positive and negative correlation (P < 0.05) with fat and moisture, respectively. Gumminess followed similar pattern to that of hardness. Moisture and fat had negative and positive effect respectively (P < 0.01) on adhesiveness. Chewiness was negatively and positively influenced (P < 0.01) by moisture and fat of sandesh, respectively. © 2010 Society of Dairy Technology.


Pagedar A.,National Dairy Research Institute | Pagedar A.,Ashok and Rita Patel Institute of Integrated Studies and Research in Biotechnology and Allied science | Singh J.,National Dairy Research Institute | Singh J.,Product and Process Development Group | Batish V.K.,National Dairy Research Institute
Journal of Dairy Research | Year: 2012

The present study investigates the effect of adaptive resistance to ciprofloxacin (Cip) and benzalkonium chloride (BC) on biofilm formation potential (BFP), efflux pump activity (EPA) and haemolysin activity of Escherichia coli isolates of dairy origin. All the isolates, irrespective of antimicrobial susceptibility, developed significant adaptive resistance (P < 0•05). All the resistant phenotypes (antibiotic resistant: AR; & biocide resistant: BR) were stronger biofilm former and post-adaptation, an insignificant change was observed in their BFP. Whereas, post-adaptation, non-resistant isolates (antibiotic non-resistant: ANR; biocide non-resistant: BNR) transformed from poor or moderate to strong biofilm formers. Post-adaptive percentage increase in EPA was highly significant in non-resistant categories (P < 0•01) and significant at P < 0•05 in BR category. Interestingly, post-adaptive increase in EPA in BR isolates was more than that in AR yet, the latter exhibited greater adaptive resistance than the former. These findings indicated prevalence of some other specific resistance mechanism/s responsible for adaptive resistance against Cip. Strain specific variations were observed for stability of adaptive resistance and haemolysin activity for all the categories. Our findings especially in reference to post-adaptation upgradation of BFP status of non-resistant isolates seems to be providing an insight into the process of conversion of non-resistant isolate into resistant ones with enhanced BFP. These observations emphasize the serious implications of sub-lethal residual levels of antimicrobials in food environments and suggest a role of food chain in emergence of antimicrobial resistances. © 2012 Proprietors of Journal of Dairy Research.


Pagedar A.,National Dairy Research Institute | Singh J.,National Dairy Research Institute | Singh J.,Product and Process Development Group | Batish V.K.,National Dairy Research Institute
Journal of Basic Microbiology | Year: 2011

The present study was undertaken to investigate the role of efflux pump activity (EPA) in conferring adaptive and cross resistances against ciprofloxacin (CF) and benzalkonium chloride (BC) in dairy isolates of Pseudomonas aeruginosa. Biofilm formation potential was correlated with development of adaptive resistance in originally resistant strains. Irrespective of parent strains's susceptibility, isolates developed substantial adaptive resistance against CF and BC. Significant difference was observed in ability of non resistant isolates to develop adaptive resistance against CF and BC (P < 0.02) and subsequent cross resistance. EPA was quantified using EtBr (Ethidium Bromide) model and its role was more prominent [confirmed by its inhibition using efflux pump inhibitor (EPI) 2,4-dinitrophenol (DNP)], in conferring adaptive resistance (P = 0.147) than cross resistance (P = 0.343). Reduction in adaptive resistances due to EPI was more evident in originally non resistant strains, which reaffirms EPA as probable mechanism of adaptive resistance. The present study perhaps first of its kind, suggests an active role of EPA in conferring adaptive and cross resistances in food related P. aeruginosa isolates and supports reverse hypothesis that antibiotic-resistant organisms eventually become tolerant to other antibacterial agents as well. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Singh J.,National Dairy Research Institute | Singh J.,Product and Process Development Group | Batish V.K.,National Dairy Research Institute | Grover S.,National Dairy Research Institute
Dairy Science and Technology | Year: 2011

In this study, a molecular beacon-based duplex real-time PCR assay was developed for the simultaneous detection of Listeria monocytogenes and Salmonella spp. by targeting their virulence genes hly and invA, respectively. The detection sensitivity of the assay in reconstituted non-fat dried milk (11%) was 3 and 4 log cfu mL -1 for L. monocytogenes and Salmonella spp., respectively, without any pre-enrichment. However, after pre-enrichment of the samples in brain heart infusion broth for 6 h, the assay could detect as low as 1 log cfu of both the pathogens. The assay was quantifiable for the respective pathogens over 5 and 4 log cfu mL -1 with regression coefficient of 0.9956 and 0.9905. On application of the developed assay on 60 dairy products, one sample of raw milk was positive for L. monocytogenes, while Salmonella spp. was detected in one sample of ice cream. The performance of the duplex assay was validated using microbiological methods and commercial individual pathogen detection kits, which further affirmed the performance of the assay by positively detecting the same samples. The developed assay can be used to monitor the quality of dairy products in context of L. monocytogenes and Salmonella spp. © INRA and Springer Science+Business Media B.V. 2011.


Singh J.,National Dairy Research Institute | Singh J.,Product and Process Development Group | Batish V.K.,National Dairy Research Institute | Grover S.,National Dairy Research Institute
Journal of Food Science and Technology | Year: 2012

The present investigation reports development of post real time PCR (RTi-PCR) - melt curve analysis for simultaneous detection of Listeria monocytogenes andSalmonella spp. The optimal Sybr Green I (SG-I) concentration of 1.6 μM resulted in two specific peaks with melting temperature (Tm) of 79.90±0.39 °C and 86.29± 0.13 °C for L. monocytogenes and Salmonella spp respectively. The detection sensitivity of the assay in reconstituted non-fat dried milk (NFDM; 11%) spiked with the target pathogens at different levels was 3 log cfu per ml of each pathogen. However, the sensitivity was improved up to 1 log cfu per ml by including pre-enrichment step of 6 h. On application of assay on 60 market samples, one sample each of raw milk and ice cream was detected positive for L. monocytogenes and Salmonella spp. Assay was quite specific as no cross reactivity with non target cultures could be observed. The developed assay can find valuable application in monitoring dairy products for the presence of L. monocytogenes and Salmonella spp. to ensure their microbiological quality and safety. © Association of Food Scientists & Technologists (India) 2011.

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