Department of Food Processing Technology

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A comparative analysis of different pitching rates on castle lager beer flavour stability:
(International Journal of Nutrition and Food Sciences, 2014-10-20) Muredzi, Perkins; Chiridza, Lyneete Tendai; Moyo, Dinga.N; Winini, Clive
Beer stability is a critical quality parameter and there is vast amount of research that has been done in attempt to understand and optimise it. The research study was incited by the result of low lag time (potential to resist staling) and high T150 (degree of staling) in one of the main stream brands at the beer processing firm, which caused the beer to stale much faster than normal. The research focused on the flavour stability aspect of beer stability and different methods of analysis were employed to investigate the effect of different pitching rates on products of yeast metabolism in-turn flavour stability. Results revealed that beer fermented with a low pitching rate had a high amount of sulphur dioxide which meant the Lag Time was also high due to sulphur dioxide exerting anti-oxidant properties which prevented oxidation of beer for longer periods than beer fermented with a high pitching rate. The results also revealed that there is no significant difference in these beers regards sensory analysis following analysis using the t-test
Comparative Study of Degradation Kinetics of Ascorbic Acid (Vitamin C) in Tray Drying, Solar Drying and open Sun Drying of Pineapple Slices
(Austin Journal of Nutrition & Metabolism, 2015-06-01) Gwala, W; Padmavati, R
A comparison of degradation kinetics of ascorbic acid was done on tray, solar and open sun drying of pineapples. Thin slices of 10mm±3 thickness were equally weighed and divided into three samples of 300g each. One 300g sample was placed in a tray dryer and dried at a temperature of 60oC, the next 300g sample was placed in the solar dryer and another 300g sample was placed on a tile for open sun drying and dried under fluctuating temperatures. Samples were taken at half hour intervals and analysed for vitamin C content over the drying period using the 2,6 dinitrophenolindophenol dye titration method. The residual vitamin C content in tray drying was least at 11.25 mg/100g of sample. This was followed by sun drying with a residual vitamin C content of 19.5mg/100g of sample. Solar dried sample showed the highest vitamin C retention with 29.25mg/100g of sample weight. The degradation kinetics were analysed using the first order fractional Model and the Weibull Model. The correlation coefficient (R2) was calculated for goodness of fit. The Weibull model had the best fit. However deviation from first order degradation kinetics of vitamin C was noted.
A concise review of yam (Dioscorea spp.) starch: extraction, chemical composition, physicochemical properties and its potential food applications
(Taylor & Francis, 2024-12-30) Mawoneke, Kurai Gareth; Kwiri, Raphael; Ndemera, Melody
Substantial studies have been conducted on the starches derived from various yam species. These studies have examined numerous extraction methods, including acid, alkali, ammonia, water and enzymatic techniques, each yielding between 10–20% starch. The physicochemical properties of yam starches have been extensively characterized, evaluating factors, such as granule size, amylose content (ranging from 0 to 40%), gelatinization behavior and rheological profiles. Notably, the yam species D. esculenta and D. dumoterum exhibit lower amylose levels, while D. trifida can present as a waxy starch with less than 2% amylose. Minimal variation has been observed in the composition, patterning and characteristics across D. cayenensis and D. rotundata starches. Yam tubers are composed of 60–80% starch by dry matter, playing a fundamental role in the quality of yam-based foods. Yam starches have demonstrated potential as thickeners, fat replacers and edible film formers due to their physicochemical attributes, particularly their gelling properties which enhance texture and functionality. However, the industrial utilization of yam starches remains limited due to a lack of systematic data and standardized isolation methods. Further research is needed to optimize extraction protocols and expand the food applications of this versatile starch.
Development and evaluation of a plantain-peanut sandwich for the Nigerian market
(. International Journal of Nutrition and Food Sciences, 2014-06-19) Malomo, Olu; Uche, E; Adekoyeni, O. O; Alamu, E. A
Protein-energy malnutrition is a common nutritional disorder in developing countries and constitutes a major public health problem in young children and elderly people. This project is aimed at evaluating the acceptability of plantainpeanut sandwich and roasted at different temperatures. A plantain-peanut sandwich consists of minced protein stuffed into a carbohydrate source made into a roll as a food product. The plantain was roasted at two different temperatures then later enriched with 5%, 10% and 15% peanut butter. The crude protein and crude fibre contents of the plantain samples roasted at 200oC and 240oC showed no significant difference (P˃0.05) while the ash, fat and carbohydrate contents showed that there was a significant difference (P˂0.05). Results of the proximate composition showed that there was significant difference (P˂0.05) at the two different roasting temperatures of 200oC and 240oC when enriched at 5%, 10% and 15% levels with peanut butter. This pattern of significant increase was also observed with the amino acid profiles at the two different roasting temperature levels.
Effects of soya bean meal feed properties on extrusion failures and implementing a solution.
(International Journal of Nutrition and Food Sciences, 2013-03-10) Muredzi, Perkins; Nyahada, Moses; Mashswa, B.W
This research was a contribution on the optimization of extrusion process by determining the effects of feed properties on extrusion failures and implementing a solution. The objectives of the research were to increase the set soy meal to chunk conversion standard from 65% to 80%; to determine the effects of feed properties on extrusion failures; to determine the best conditions of the feed properties that promote an effective extrusion cooking process; and to determine a solution of optimizing these feed properties for successful extrusion. The research was company based and it followed the failures of extrusion experienced at Monmouth Path Investment (Pvt) Ltd in Waterfall, Harare. This research was limited to feed properties such as fat content, moisture content and particle size as the factors that cause extrusion failures. The determination of moisture content was done by using a moisture analyzer, fat content was determined through the Soxhlet method and the particle size of the feed was determined through sieve analysis. The results revealed that extrusion process was most successful when the soy meals fat content was greater than 6.0%, with a moisture content less than 6.0% and particle size range of 0.95-1.0mm. The process of optimization of extrusion process was solved by designing an extrusion calculator and blending ratio factors. The objective of determining the effects of feed properties on extrusion failures was achieved as well as that of implementing a solution. The objective of increasing Monmouth Path’s standard soy meal/chunk conversion was partially achieved since the implemented solution is not yet measurable.
Food is Medicine -
(LAP Lambert Academic Publishing., 2013-07-30) Muredzi, Perkins
A combination of the words "nutrition" and "pharmaceutical," the term nutraceutical encompasses foods or food products that claim to prevent chronic diseases, improve health, delay the aging process, and/or increase life expectancy. Products in this category range from isolated nutrients, dietary supplements and specific diets to genetically engineered foods, herbal products, and processed foods such as cereals and beverages.The area of Nutraceuticals is relevantly new and hence this publication serves to be most vital for scholars studying pharmaceutical sciences and related disciplines and as a reference for college freshman intending to have more understanding of this emerging area. This book by Dr. Muredzi sets the tone for future editions and serves to give an enlightened introduction to this emerging discipline
Food Security and Intellectual Property Rights –
(LAP Lambert Academic Publishing, 2013-01-01) Muredzi, Perkins; Sackey, Emmanuel
This book gives an understanding of the relationship between IPRs and Food Security, the current status of food security in Sub Saharan Africa and discusses the issues and concerns regarding IPRs and Food Security. It also considers the question of sui generis protection from the perspective of food security. It examines the extent to which existing IPRs can fulfill the twin goal of promoting technological development and food security. It also examines further options that are open to Sub-Saharan Africa countries under the TRIPS Agreement and beyond the TRIPS Agreement, taking into account other treaties such as the International Treaty on Plant Genetic Resources for Food and Agriculture (International Treaty on PGRFA).
Grewia bicolor seed oil: Putative pharmaceutical, cosmetic and industrial uses
(South African Journal of Botany, 2015-06-12) Nyakudya, Trevor,T; Magwa, Michael,L; Chivandi, Elton; Nosenga, Noseiphi; Erlwanger, Kennedy L; Gundidza, Mazuru; Gundidza, Ernegy; Muredzi, Perkins
The physicochemical characterisation, seed oil content and fatty acid profile of oil extracts from Grewia bicolor seeds collected in Zimbabwe were performed using standard extraction and chromatographic techniques. The main objective was to determine the potential domestic and industrial usefulness of the G. bicolor seeds. The G. bicolor seeds yielded 4.80% of brownish-orange oil that had an acceptable odour. The seed oil consisted of saturated (20.20%), monounsaturated (25.10%) and polyunsaturated (54.41%) fatty acids. Palmitic acid (11.46%), stearic acid (5.77%), oleic acid (19.33%) and linoleic acid (54.41%) were the main fatty acids in G. bicolor seed oil. The oil had a high acid value (0.53 mg KOH/g), iodine value (39.21 g I2/100 g oil) and saponification value (130.43 mg KOH/g) compared to published data on other nutritionally and ethnomedicinally important plant seed oils. We conclude that the G. bicolor seeds are low oil yielding, whose oil could be used as a potential source of palmitic, stearic, oleic and linoleic acids and may potentially be utilized as an industrial ingredient in the manufacture of soaps, pharmaceutical products, and cosmetics. Further studies are required to explore the possibility of using this seed oil in industry.
Investigation of shelf-life extension of sorghum beer (Chibuku) by removing the second conversion of malt
(Elsevier, 2008-12-04) Kutyauripo, Josphat; Parawira, Wilson; Tinofa, Sharai; Kudita, Ivy; Ndengu, Clement
The effect of removing the second step of malt conversion in the brewing of Chibuku beer was investigated with the intention of extending the shelf-life of the product. Chibuku was brewed in the laboratory scale fermenters using Delta Beverages' standard brewing procedure. A variation was made where the second malt conversion was not conducted on one brew. The effect of increasing pasteurisation time was also investigated. The extension of shelf-life was determined by following the physicochemical and the sensory profile of the products for a period of ten days under sub-tropical ambient conditions. Ethanol productions were similar between the control and test beers (without second conversion malt). A product with overall acceptability of 70% was made from the brew without the second malt conversion and with 15 min pasteurisation at 80 °C. The product was, however, low in bite and head retention, but had less bacterial load, decreased acid production, and improved keeping quality by at least two days. However, due to contamination of the pitching yeast with lactic acid bacteria (LAB), total acids rapidly increased after 168 h and caused unacceptable sourness. Increasing pasteurisation time to 20 min reduced bacterial load of the wort to figures as low as 2 × 103 cfu/ml. General hygiene levels of the brewery were acceptable and no coliforms were detected in the product or contact surfaces along the production line. Bacterial contamination of the product mainly comes from the raw materials with pasteurisation greatly reducing this load. If improved, the procedure has the potential of extending the shelf-life of the beer to beyond 168 h
An investigation on the causes of Escherichia coli and coliform contamination of cheddar cheese and how to reduce the problem
(International Journal of Nutrition and Food Sciences, 2014-09-20) Kwenda, Amanda; Nyahada, Moses; Musengi, Amos; Mudyiwa, Misheck; Muredzi, Perkins
The aim of this study was to investigate the causes of E. coli contamination of Cheddar cheese through the application of Hazard Analysis Critical Control Points (HACCP) principles. Cheese samples were analyzed for E. coli and coliforms after production, during the validation stage, as well as at the verification stage. Average E. coli and coliform counts were analyzed statistically using the t-test. Results showed that after the implementation of the corrective measures there was a decrease in E. coli and coliform counts at the 5% level of significance. Results presented in this study also show that manufacturing Cheddar cheese whole observing high standards of hygiene improves the reduces E. coli and coliform contamination of the product, even though the problem is not completely eliminated.
ISO 14040 Life Cycle Assessment (LAS) as a tool for effective environmentally friendly waste management in the Food Industry
(National Renewable Energy Labaratory., 2009-01-02) Muredzi, Perkins
Life cycle assessment (LCA) is an analytical tool for the systematic evaluation of the environmental aspects of a product or service system through all stages of its life cycle. The food production industry requires large inputs of resources and causes several negative environmental effects. The food production systems are oriented and optimized to satisfy economic demands and the nutritional needs of a rapidly growing world population. Environmental issues, however, have not been given much attention. This review article discusses Life Cycle Assessment (LAS) as a tool for effective environmentally friendly waste management in the Food Industry and gives case studies and recommendations for the industry.
Isolation of citric acid producing Aspergillus niger strains
(LAP LAMBERT Academic Publishing, 2013-01-05) Muredzi, Perkins; Nyati, Hilda; Mudyiwa, Misheck
Microbiological quality of Gonimbrasia belina processed under different traditional practices in Gwanda, Zimbabwe
(International Journal of Current Microbiolgy Applied Sciences, 2014-01-02) Mujuru, Felix; Winini, Clive; Kwiri, Raphael; Nyambi, Clarice; Moyo, Dinga.N
TheaimofthisstudywastoinvestigatethemicrobiologicalqualityofMopaniWorms(MW)(Gonimbrasiabelina)processedunderdifferenttraditionalpracticesin Gwanda,Zimbabwe.FreshlyharvestedMopaneworms(MW)weredeguttedusingbarehandsorglovedhands.Thedeguttedwormsweresub-dividedinto4equal portions and subjected to different traditional drying methods namely, boiling insaltedwater(5%w/wsalt)for30minutesandsolardrying,openpanroasting,drumroastingandhot-ashdryingtoapproximately15%moisturecontent.Thereafter,driedMWsweremicrobiologicallyanalysedagainstindicatormicro-organisms(totalbacteriacounts,coliformsandEscherichiacoli)andpathogens(Salmonella spp.andStaphylococcusaureus)aswellasspoilageorganisms(yeastandmolds).Microbiologicaltestsconductedshowedthat,totalbacteriacounts(TBC)wererelativelylowwithvaluesrangingfrom10-2500CFUg-1. Significantly,deguttingMWsusingbarehandsfollowedbydrumroastingandboilinginsaltwatercoupledwithopenpanroasting,hadtheleastTBC(10CFUg-1and30CFUg-1)respectively.ColiformsandE.coliwerealsodetectedinMWswithvaluesrangingfrom0-43CFUg-1and0-30CFUg-1respectively(barehandsdegutted)whilstinglovesdeguttedMWscoliformscountswere0-45CFUg-1andE.colicountswere0-35CFUg-1.Furthermore,someMWsespeciallyashindriedsamplesthatcontainedvaryinglevelsandtypesofyeastsandmoldsthatincludedFusariumandPenicillium.NoSalmonellaspecieweredetectedinallsampletested.Thestudyshowedthat,MWprocessingmethodandsubsequenthandlingareimportantparametersindeterminingthetypeandlevelsoftheircontamination.Assuch,itisimperativeforharvestersandprocessorstoobservegoodharvestingandmanufacturingpracticesandfollowprotocolsthatdonotresultinre-contamination of produce as this might present a danger to the public consumers.
Microbiological safety of cooked vended foods in an urban informal market:
(International Journal of Nutrition and Food Sciences, 2014-05-30) Mpofu, Enock; Tongonya, Jeritah; Gwala, Shannon,T; Makarichi, Lydia; Kwiri, Raphael; Winini, Clive; Mujuru, Felix; Muredzi, Perkins
The study presents an investigation of the microbiological safety of cooked vended foods in an urban informal market in Harare, Zimbabwe. Analyses were performed on 200 samples of mostly vended ready to eat foodstuffs (comprising chicken and beef stew, egg rolls, doughnuts and boiled mealie cobs) between the month of October and November 2012. Samples were analyzed against different types of indicator micro-organisms namely total aerobics, coliforms and Escherichia coli and pathogens (Salmonella spp. and Staphylococcus aureus). Significantly, early morning samples were less contaminated than afternoon samples (p<0.05). No Salmonella spp. was detected in any of the foodstuffs analysed, though S. aureus and E.coli were present (respectively ranges from 3-62x102 cfu/g and 6-49x101 cfu/g). Respectively, nearly 85.5% and 53% of the samples were highly contaminated with S. aureus and E. coli. Correspondingly, total aerobic plate count ranged from 11-172x103cfu/g, while coliform count ranged from 8-85 x102 cfu/g. Subsequently, the study showed that informally vended foods might contain pathogenic microorganisms which signify a risk for human health. The importance of adequate measures to guarantee food safety was underscored.
Microbiology and Immunology
(HIT, 2018-05-15) HIT
Novel Non Thermal Preservation Techniques in Meat Processing: High Hydrostatic Pressure as a Model Technology
(Science Publishing Group, 2014-01-30) Muredzi, Perkins
Consumers demand high quality and convenient meat products, with natural flavour and taste, and very much appreciate the fresh appearance of minimally processed food. To harmonize or to blend all these demands without compromising safety, it is necessary to implement new preservation technologies in the meat industry and in the food industry in general. High hydrostatic pressure (HHP) represents an attractive non-thermal process for meat products to avoid post-processing contamination. This review paper discusses the pivotal role played by HHP in meat processing and gives a general analysis of shelf life extension in meat products treated with HPP, the main technological effects of HHP in meat and a study case on “Mechanically recovered poultry meat sausages manufactured with High Hydrostatic Pressure”
Preparation of Adansonia digitata flavoured Soy Milk based yoghurt
(Harare Institute of Technology, 2014-05-22) Muredzi, Perkins
An Adansonia digitata flavoured Soy Milk based yoghurt is prepared by leaching soybean meal with aqueous solution having a pH of 4 to 5 to remove sugars without removing protein, leaching a resultant residual sugar free cake with an aqueous solution having a pH above 7 to dissolve protein material, adjusting the pH of a resulting protein containing filtrate to 6.5 to 7.0 adding sucrose to the filtrate, flavouring with Adansonia digitata powder and homogenising to produce a flavoured Soy Milk, sterilising at about 116 0C and fermenting with a mixed bacterial culture comprising in addition to Lactobacillus delbrueckii, a strain capable of stimulating growth of Lactobacillus delbrueckii , in an incubator (at 37-40 0C) to produce Soy Yoghurt.
Proximate composition of pumpkin gourd (Cucurbita pepo) seeds from Zimbabwe ,
(International Journal of Nutrition and Food Sciences., 2014-06-30) Winini, Clive; Kwiri, Raphael; Musengi, Amos; Mudyiwa, Misheck; Nyambi, Clarice; Muredzi, Perkins; Malunga, Abigail
Curcubita pepo seeds have been widely consumed in Zimbabwe way back in the 1970s, but still locally, there is no data on the nutritional quality of Curcubita pepo seeds, hence the study attempted to avail this information. Curcubita pepo seeds from selected places in Zimbabwe were analysed. The proximate analysis including major nutrients and minerals were determined. The C. pepo seed had a moisture content of 5.662±0.016gkg-1. Significantly, Curcubita pepo had high amounts of crude oil and proteins as compared to other edible oil rich seeds. The crude oil content and protein were 43.460±0.098gkg-1 and 32.860±0.103gkg-1 respectively. Other components such as carbohydrates, crude fibre and energy were 12.160±0.142gkg-1, 2.578±0.007gkg-1 and 562.82±0.132gkg-1 correspondingly. Ash content was 3.324±0.010gkg-1 which was further analysed into various major minerals giving analysed means as Na (67.956±0.037gkg-1), Zn (1.244±0.010gkg-1), P (1040.8±0.663gkg-1), Fe (11.980±0.086gkg-1), Ca (141±0.316gkg-1) and Mg (344.6±0.245gkg-1). The findings indicated that C. pepo seeds are a good alternative source of highly nutritious food for instance proteins and lipids as well as minerals (Mg, Ca, Zn, P and Fe) that could greatly contribute to human nutritional requirements. However, it still remains important to further profile the quality of the lipids and proteins from C. pepo seed so as to verify their essentiality and availability to the human body as well as evaluating the presence of other bioactive and antinutritional factors that might be present in these seeds.
Selected Articles in Food Science & Technology for College Graduate Students
(Science Publishing Group, 2015-04-05) Muredzi, Perkins
Food Science represents the application of the basic sciences, biotechnology, and engineering to the production, processing, packaging, distribution, and evaluation of foods. Food science and food technology complement production agriculture by developing methods that minimize waste and improve the quality, utility, safety, attractiveness, and shelf life of foods. Food scientists strive to improve the efficiency of food processing while ensuring high quality, nutritious, safe, and convenient food products. To this end, they employ the principles of chemistry, physics, biochemistry, microbiology, engineering, nutrition, and management in an integrated manner. Food scientists require specialized education and technical training. Advanced studies in food science and technology taken by graduate students provide a broader, more varied education than is possible in the other study programmes. Graduate students are more often expected to take courses in food chemistry, food engineering and processing, food microbiology, nutrition, and food marketing as well as in the supporting disciplines and commodity areas in their special interests. Graduate students therefore require exposure to information regards immerging and critical topics in the various areas offered in their studies. To complement taught courses some programmes offer seminars on advanced topics or food research areas. This collection of articles serves to give the graduate student a varied portfolio of articles as reference material for the various disciplines of food science and technology under study thus enriching knowledge in selected critical topics
Underexploited tuber crops in Zimbabwe:
(Horticultural Research Centre, 2002-01-01) Dhliwayo, Patient D.
The Livingstone Potato iPlectranihus esculentus) is one of the edible indigenous tuber crops commonly grown under both dryland and wetland conditions in parts of the eastern districts of Zimbabwe. AIr" though the crop could be considered of minor importance globally in terms of total production and commercial value, it plays a significant role in human nutrition in different communities of some countries including Zimbabwe. In addition to its acceptance and nutritional value, the Livingstone Potato has been associated with certain therapeutic properties. A study was carried out on P. esculenius in the major producing areas of Zimbabwe to investigate the extent and importance of production of this crop. At least 15 varieties of the Livingstone Potato are currently grown under the farmers' traditional practices in the country. Scientific recommendations on the agronomy of this crop have neither been developed nor disseminated to growers-This lack of mechanisms for promoting and investigating this little known but potentially useful indigenous crop has constrained r-"improved production and utilization. ':;radual depletion of varieties is being ex- -:»:perienced and a massive effort isrequired to safeguard the survival of this orphaned genetic resource. The Livingstone Potato could become an important complement for other root and tuber crops if essential research needs, development and policy issues are addressed and satisfied. This report challenges researchers, policymakers and other related disciplines to assist in achieving a more efficient and balanced exploitation of P. esculentus.