Title page for ETD etd-07122006-101526


Document Type Master's Dissertation
Author Takalani, Thakani Kennedy
URN etd-07122006-101526
Document Title Title Preservation of Tshidzimba, a cereal-legume composite porridge, through fermentation, canning and drying
Degree M Inst Agrar ( Food Processing)
Department Food Science
Supervisor
Advisor Name Title
Prof J R N Taylor Committee Chair
Dr A Minnaar Committee Co-Chair
Keywords
  • food preservation drying
  • food preservation fermentation
  • food preservation canning
Date 2001-09-01
Availability unrestricted
Abstract
Traditional African foods are often rich in nutrients and play an important role in increasing variety in diets of people in rural areas. Tshidzimba is popular amongst the Vhavenda of South Africa. It is made from maize samp, milled peanuts and salt. However, it has a very short shelf life when stored at ambient temperature. Canning, drying and fermentation of Tshidzimba were investigated to increase shelf-life. Factors investigated were microbiological quality, nutrient content (in terms of fat and protein content), levels of essential amino acids, water activity and sensory acceptability.

Unpreserved Tshidzimba had very high total plate counts, yeasts and moulds after 3 days of storage at 25C. Fermentation reduced the yeasts and moulds by 102 and total plate counts by 103 after 21 days of storage at 25C from those of unpreserved Tshidzimba. Drying reduced the yeasts and moulds by 104 and total plate counts by 105 after 21 days of storage at 25C. Anaerobic spore formers were not detected in canned Tshidzimba after 21 days of storage at 25C.

Drying reduced the fat content probably due to fat oxidation at the elevated drying temperature (50C). However, in general the preservation methods had little effect on the general nutrient content of Tshidzimba.

Tshidzimba protein showed low lysine value compared to the estimates of amino acid requirements for infants. For Tshidzimba to be a good source of nutrients for infants, fortification with a higher proportion of legume grains is recommended. Drying seemed to increase lysine (2.61 g/100 g protein) compared to that of unpreserved Tshidzimba (2.28 g/100 g protein), while canning reduced lysine (1.97 g/l00 g protein), probably due to its participation in Maillard reaction at the high canning temperature (116C/70 min). Fermentation increased methionine content probably due to fermentative microorganisms, which are known to produce some amino acids while fermenting food products. Canning seemed to have reduced the methionine content possibly due to Maillard reaction.

Consumer panellists indicated that of the preserved Tshidzimba, dried Tshidzimba had high acceptance compared to canned and fermented Tshidzimba. Some panellists disliked the sour taste of fermented Tshidzimba. Dried Tshidzimba was perceived to have a firmer texture compared to unpreserved Tshidzimba. Further research could help to determine the appropriate temperature/time combination that can least affect the texture of dried Tshidzimba.

2001 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.

Please cite as follows:

Takalani, TK 2001, Preservation of Tshidzimba, a cereal-legume composite porridge, through fermentation, canning and drying, MInstAgrar dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-07122006-101526/ >

H1119/ag

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