Publications by authors named "P Nema"

24 Publications

Microbial inactivation by high pressure processing: principle, mechanism and factors responsible.

Food Sci Biotechnol 2021 Jan 6;30(1):19-35. Epub 2020 Oct 6.

Department of Wine, Food and Molecular Biosciences, Lincoln University, Lincoln, Canterbury 7647 New Zealand.

High-pressure processing (HPP) is a novel technology for the production of minimally processed food products with better retention of the natural aroma, fresh-like taste, additive-free, stable, convenient to use. In this regard safety of products by microbial inactivation is likely to become an important focus for food technologists from the research and industrial field. High pressure induces conformational changes in the cell membranes, cell morphology. It perturbs biochemical reactions, as well as the genetic mechanism of the microorganisms, thus ensures the reduction in the microbial count. Keeping in view the commercial demand of HPP products, the scientific literature available on the mechanism of inactivation by high pressure and intrinsic and extrinsic factors affecting the efficiency of HPP are systematically and critically analyzed in this review to develop a clear understanding of these issues. Modeling applied to study the microbial inactivation kinetics by HPP is also discussed for the benefit of interested readers.
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http://dx.doi.org/10.1007/s10068-020-00831-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7847475PMC
January 2021

Ultrasonic and osmotic pretreatments followed by convective and vacuum drying of papaya slices.

J Sci Food Agric 2021 Apr 19;101(6):2264-2272. Epub 2020 Oct 19.

Department of Food Engineering, National Institute of Food Technology Entrepreneurship and Management (NIFTEM) Kundli, Sonipat, India.

Background: Papaya fruit is highly nutritive, but very fragile, and thus has a limited shelf life. Drying is essential to preserve it for longer durations. In this work, osmotic dehydration (OD) with and without ultrasound (US) was applied to papaya slices as a pretreatment in conjugation with vacuum (VD) and convective air drying (AD). Drying was carried out in a novel dryer. Moisture content, drying time, water activity, total color change, total phenolic content, radical scavenging activity, texture, and Fourier-transform infrared (FTIR) spectrums were evaluated for fresh and dried papaya slices.

Results: It was observed that US-assisted osmotic dehydration (USOD) followed by VD had the lowest drying time with highest retention of phenols and antioxidants as compared to other drying techniques. Higher phenols and antioxidants in US-pretreated samples were attributed to the release of trapped intra-cellular polyphenols by cavitation. However, the color characteristics and texture of OD pretreatment followed by convective AD slices were found to be better. Color retention could be due to carotenoid preservation, which would be degraded in other treatments, whereas lower brittleness was associated with lower pectin. Infrared spectroscopy confirmed the retention of phytochemicals and antioxidants in dried papaya slices that were subjected to pretreatment.

Conclusion: Pretreatment before drying enhances the end product quality of dried papaya slices. The results of this study highlight that USOD-VD is effective for nutrition preservation while OD-AD is suitable for preserving physical characteristics. © 2020 Society of Chemical Industry.
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http://dx.doi.org/10.1002/jsfa.10847DOI Listing
April 2021

Low pressure superheated steam drying of onion slices: kinetics and quality comparison with vacuum and hot air drying in an advanced drying unit.

J Food Sci Technol 2018 Oct 24;55(10):4311-4320. Epub 2018 Aug 24.

Department of Food Engineering, National Institute of Food Technology Entrepreneurship and Management (NIFTEM), Kundli, Sonepat, Haryana 131028 India.

Pungency is important characteristics of onion and during processing it is generally reduces. Low pressure superheated steam drying (LPSSD) is gaining importance due to energy and product benefits. It results in better retentions of bioactive components. So, in current study onion slices were dried using low pressure superheated steam, and compared with vacuum and hot air drying at different temperature in NIFTEM advance drying unit. Among the selected models, Page's model gave a better prediction and satisfactorily described drying characteristics of onion slices. The Activation energy was found to be 41.87 kJ/mol in LPSSD. Quality of product, i.e. retention of color, rehydration ratio, thiosulphinate content, total phenol content and antioxidant activity, were better at 70 °C using LPSSD, at 60 °C using VD and HAD, as compared to other drying temperature in respective drying technologies used. Significant differences in quality of the dried product were also observed due to drying temperature in different drying techniques.
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http://dx.doi.org/10.1007/s13197-018-3379-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6133842PMC
October 2018

Eccrine angiokeratomatous hamartoma: case report of a 1.5-year girl.

J Surg Case Rep 2017 Jul 7;2017(7):rjx133. Epub 2017 Jul 7.

Department Of General Surgery, PCMS & RC, Bhopal 462010, MP, India.

Eccrine angiokeratomatous hamartoma is a rare newly defined vascular lesion of the skin, the first case of which was reported in 2006 (Kanitakis J, Ly A, Claudy A. Eccrine angiokeratomatous hamartoma: a new variant of eccrine hamartoma with angiokeratoma. 2006; : S104-6). On web Literature Search, Only three previously documented cases of the lesions were found. A 1.5-year-old female child presented with a painless lesion on her right leg since birth which has been gradually increasing in size and recently developed central ulceration. Histological examination of the excised lesion confirmed the diagnosis. This is the first of the cases to be reported in paediatric age-group (<2 years).
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http://dx.doi.org/10.1093/jscr/rjx133DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5570046PMC
July 2017

Performance of Free Water Surface Constructed Wetland Using Typhalatifolia and Canna Lilies for the Treatment of Domestic Wastewater.

J Environ Sci Eng 2014 Jan;56(1):93-104

Discharge of untreated wastewater or partially treated wastewater into surface water bodies or on to land is a major cause of surface and ground water pollution thereby posing health hazards. Conventional wastewater treatment is generally not preferred for small communities due to higher capital and maintenance costs and lack of skilled supervision required for operation and maintenance. A constructed wetland treatment appears to be an appropriate alternative that can be employed both in developed and developing countries. A constructed wetland system is simple to construct and operate with low cost, and hence worth considering for the treatment of municipal wastewaters, especially from small communities. In this context, the site for carrying out the studies related to wastewater treatment was chosen at Kavikulguru Institute of Technology and Science (KITS), Ramtek, Dist. Nagpur. A Free Water Surface Constructed Wetland (FWSCW) of size 22.00m x 6.50 m x 0.60m was constructed at KITS, Ramtek. The performance of FWS CW system was studied for domestic wastewater treatment with theoretical hydraulic retention times of 10 days, 7 days and 5 days. Important parameters, such as BOD5, COD, TSS, NH4-N, PO4-P, DO, pH and faecal coliforms in both raw and treated wastewaters were monitored during a macrophytes life cycle. Based on the studies, it is concluded that minimum 5 days HRT is necessary for the treatment of wastewater in FWSCW using Typhalatifolia or Canna Lilies. Typhalatifolia is better in removal of pollutants from the wastewater in comparison to Canna Lilies and hence, is recommended for use in constructed wetland. The nutrient uptake capacity of Typhalatifolia is also quite encouraging and hence has great potential for application in treating wastewater from fertilizer industry. During the application of kinetic model, the observed and predicted values in respect of BOD, TSS and NH4-N in case of Typhalatifolia and BOD, COD and TSS in case of Canna Lilies were found in good agreement corroborating the best fit mathematical model presented. The batch type constructed wetland system is an appropriate system for low and intermittent flow conditions.
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January 2014