Studies on the concentration of onion juice

Shere, Prerana Dayasagar (2005) Studies on the concentration of onion juice. Masters thesis, University of Mysore.

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Abstract

This Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page.

Item Type:	Thesis (Masters)
Additional Information:	<p align="justify">Efforts have been made in the present investigation to produce a new product i.e. onion juice by enzymatic treatment and the juice were concentrated by thin film evaporator.Studies on storage behavior of concentrated juice have also been conducted.Two-onion verities i.e. red and white verity were screened for its higher pungency and higher recovery. The red variety was found to contain higher pyruvic acid and higher pungency as compared to white variety and hence the red variety was used for preparation of onion juice. The onion juice was extracted using the pectinase enzyme at 0.2 and 2.0% levels at 30oC and 45oC for 30 to 120 minutes of incubation period. The results indicated that increasing the enzyme concentration and temperature are not beneficial in getting the higher yields. The juice yield at 0.2% enzyme level and 2% enzyme level were almost same. Therefore, the onion juice was extracted using 0.2% enzyme level at 30oC and 90 minutes incubation period to get maximum juice recovery at economical level. The onion juice so obtained was finally concentrated using thin film evaporator at 43-45oC and vacuum of 23-24 mm of mercury. The juice was concentrated to a final 60o brix. The storage studies of concentrate were carried by storing the juice in 200 ml capacity glass bottle at three temperatures i.e. room temperature, 37oC and refrigerated temperature. At the end of 30 days the results revealed that degree brix, pH, acidity of the product remained constant at all the three temperature however, the pyruvate content decreased significantly at room temperature and 37oC as compared to refrigerated stored sample. The rate of browning reaction was also elevated at higher temperature as compared to refrigerated stored sample. It was concluded from the study that red variety of onion can be used successfully for preparation of onion juice. The juice can be extracted using 0.2% pectinase enzyme at 30o C and 90 minutes incubation period with maximum recovery at economical level. The juice can be concentrated using thin film evaporator at 45oC and at a vacuum of 24 mm of mercury to a final brix of 60obrix. The concentrated juice can be successfully stored either at room temperature or refrigerated temperature without significant changes in physicochemical qualities.</p>
Uncontrolled Keywords:	onion onion juice concentration onion juice
Subjects:	600 Technology > 08 Food technology > 23 Vegetables 600 Technology > 08 Food technology > 30 Spices/Condiments
Divisions:	Human Resource Development
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	23 Feb 2007
Last Modified:	28 Dec 2011 09:26
URI:	http://ir.cftri.res.in/id/eprint/387

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