Review on gums of industrial value

A journal review of gums of industrial value.There is an increasing trend towards the use of available plant resources for food and technological applications. One class of ingredients often exploited for their texturizing capabilities are the plant polysaccharides called the hydrocolloids or gums. These compounds are long chain polymers which dissolve in water to give a thickening or viscosity-building effect. Some of these plant polysaccharides have found applications in the food, pharmaceutical, textile, mining and other industries. The United States Food and Drug Administration regulates gums, classifying these compounds as food additives. Though required at usage levels of less than two percent to achieve the desired properties in food systems, gums have become a big business. In 1991 the market of gums reached 126 metric tons at a worth of $748.7 million. There is an increased awareness of the nutritional importance of polysaccharides. The demand for water-soluble polysaccharide gums including the seaweed extracts, seed gums, plant exudates and cellulose derivatives, has slowly increased over the past few years along with population growth and the advent of easy to prepare foods. Effective use of gums requires that their chemical and physical properties be understood as much as possible. This article gives a review of some of the polysaccharide gums of industrial value

Food shortage in Zimbabwe: Can wild cereal grains be an alternative source of nutrition?

Cereals are used as staple food in most countries all over the world including Zimbabwe. Unfortunately, poor rainfall patterns have hampered the production of traditional cereals like maize and wheat leading to poverty especially in third world countries. Five wild cereal grains namely; Amaranthus hybridus, Brachiaria brizantha, Panicum maximum, Rottiboellea cochinchinensis and Sorghum arundinaceum were studied to determine their nutritional value because of their drought tolerance. Two domesticated cereals were used for comparison. The macro nutrients determined were proteins, carbohydrates, fats and minerals. Amaranthus hybridus, a wild cereal, had the highest protein and fat content of 21.44% and 11.50% respectively, compared to all the other cereal grains.  Brachiaria brizantha had the highest fibre content of 30.34% while the red variety of Sorghum bicolor had the least fibre content of 2.51%. Phosphorus was detected in all the cereal grains studied. Calcium was detected in all the cereal grains except in red variety of Sorghum bicolor. The nutritional composition of the cereal grains makes them potential alternative food sources

Sensory properties and consumer acceptance of a stirred-type yoghurt Produced from Baobab (Adansonia digitata) pulp during refrigerated storage

The baobab (Adansonia digitata L.) tree is widespread throughout the hot and drier regions of tropical Africa. The baobab pulp from the tree is an important source of nutrients in Africa as it is a rich source of amino acids, iron, vitamins C, A and E. In some African countries including Zimbabwe, the pulp is used traditionally to cure various ailments such as dysentery, inflamed gums and as an antidote to poison. Baobab pulp has many food uses and consequently the aim of the current study was to determine the sensory properties of the baobab flavoured yoghurt during storage and consumer acceptance of the yoghurt. A trained panelist evaluated the appearance, consistency on spoon, consistency in mouth, odour, flavour and overall acceptability of the yoghurt on days 1, 7, 14, 21 and 28 of storage. In all the sensory evaluations, plain yoghurt was used as a control. The consumer panelists (n = 150) evaluated taste, texture, colour, smell and aftertaste of the yoghurt. In general, the sensory scores of the baobab flavoured yoghurt and plain yoghurt decreased with storage time. The plain yoghurt had higher appearance scores from day 1 up to day 28 as compared to the baobab flavoured yoghurt and there was a significant difference (p = 0.01) in the scores of the yoghurts. On day 1 the consistency on spoon scores for both the baobab flavoured yoghurt and the plain yoghurt had the same value and from day 2 up to day 28, the plain yoghurt had the highest consistency on spoon scores as compared to the baobab flavoured yoghurt and the difference was significant (p = 0.01). The baobab flavoured yoghurt consistency in mouth scores were lower as compared to the plain yoghurt and the difference in the scores of the products was significant (p = 0.01). The odour and flavour scores of both the baobab flavoured yoghurt and plain yoghurt decreased throughout the storage period and the difference in the scores of the yoghurts was significant (p = 0.05). There was a significant difference (p = 0.05) in the overall acceptability scores of the baobab flavoured yoghurt and the plain yoghurt. Although the baobab flavoured yoghurt scores decreased with time of storage and the yoghurt had an astringent aftertaste, the consumer scores indicated that the baobab flavoured yoghurt was acceptable in terms of taste, texture, colour and smell.Key words: Baobab, flavoured, yoghurt, sensory propertie

Evaluation of FAO AquaCrop Model for ability to simulate attainable yields and water use for field tomatoes grown under deficit irrigation in Harare, Zimbabwe

Crop simulation models have an important role in evaluating irrigation management strategies for improving agricultural water use. The aim of this study was to evaluate the AquaCrop model for ability to simulate water use and tomato (Lycopersicon esculentum Mill.) fruit yields under deficit irrigation conditions. A fieldexperiment was conducted at Thornpark, University of Zimbabwe Research site over four seasons (2014 and 2017). The data collected for yield and water use were used to run and evaluate the performance of AquaCrop in predicting water use efficiency and fruit yield. Four treatments defined in relation to 100% of the crop water requirement (ETc) were simulated: T1 100% ETc; T2 80% ETc; T3 60% ETc and T4 50% ETc. The model performance was satisfactory, with a good correlation between the simulated and observed soil water content (SWC) and fruit yield (FY). All the statistical indicators (The Normalised Root Mean Square Error (R2), Root Mean Square Error (RMSE), Nush Sutcliffe Model Efficiency (EF), Pearson Correlation Coefficient (r), and Willmott’s Index of Agreement (d)) used to compare the observed and predicted parameters, showed good performance; for example the EF showed values of 0.91 for SWC, the (r) showed values of 0.95 for SWC and a FY of 2.79 and 2.39 metric tonnes ha-1 for the simulated results. The results showed that the values of the simulated FY were consistent with the measured, with corresponding coefficients of determination (R2) of 0.93. The results revealed AquaCropisable to simulate the yield of tomato and the seasonal water requirements to an appreciable degree. However, it must be pointed out that the calibration of AquaCrop suffered from lack of measured data on the progress of crop canopy cover, which is an important parameter used in developing the model. The results obtained showed that AquaCrop can be used effectively in simulating tomato production under deficit irrigation and, therefore, it can be used as a decision-making tool for irrigation management of tomatoes in Zimbabwe

Properties of (Parinari Curatellifolia) (Hacha or Chakata) Fruit from Different Parts of Harare, Zimbabwe

In most African countries, people in rural areas collect edible wild fruits that include (Parinari curatellifolia) for direct consumption or processing into food products especially during periods of food shortage. Parinari curatellifolia is a miombo woodland tree that bears green to grey oval shaped fruit that turns yellowish to brown when ripe. The purpose of the study was to determine the properties of Parinari curatellifolia fruit from Amby, Waterfalls and Acadia in Harare. The parameters evaluated include locations of fruit collection, diameter and mass, proportion of pulp, skin and stone in the fruit, moisture, mineral ash and minerals namely magnesium, iron, manganese, copper and phosphorous. Latitude and longitude positions of the trees locations were approximately E 30O and S 17O, respectively. The heights of the sites above sea level ranged from 1477 to 1528m. Diameters and masses of fruit from the three sites were significantly different (p<0.05). Moisture content of the fruit ranged from 66 to 74%. The mean pulp content was 56±5% for individual fruit units and 50±1% for bulk samples from the sampling sites. Fruit from Acadia had the highest pulp content of 60±4%. The proportion of skins and seed stones in the fruit ranged from 8 to 12.5% and 26 to 36%, respectively. Similarly as for diameters and masses, the skin, pulp and stone content of fruits from the three sites were significantly different (P< 0.05). Fruit from Amby had the highest mineral ash, potassium and calcium contents, which were 4.0±0.1, 1.5±0.1 and 0.5±0.1%, respectively. The highest levels of copper and iron were obtained in Acadia and were 0.5±0.1 and 0.8±0.2, respectively. There were no significant differences for mineral ash, P, Mg, Ca, Fe, Mn and Cu content of pulp for fruits from the three sites (P>0.05). The pulp level that was more than 50% of the fruit makes the fruit a potential raw material for food processing. The minerals in the fruit provide a source of nutrients for consumers of prepared food.Key words: Parinari curatellifolia, fruit, pulp, foo

Heavy metal content of vegetables irrigated with mixtures of wastewater and sewage sludge in Zimbabwe: Implications for human health

There is growing public concern in Zimbabwe over the illegal cultivation of vegetables on soils amended with sewage sludge or irrigated with admixtures of sewage and sewage sludge. Excessive accumulation of heavy metals in agricultural soils may not only result in environmental contamination, but lead to elevated heavy metal uptake by crops, which may affect food quality and safety. The work reported here studied heavy metal concentrations in crops irrigated with sewage sludge and sewage/sewage sludge admixtures at Firle Municipal Farm in Harare. The crops analysed in this study are heavily contaminated with the four regulated elements Cd, Cu, Pb and Zn. This contamination is at its highest in two of the staple dietary crops maize and tsunga. Tsunga leaves contained 3.68 mg kg-1 Cd, over 18 times the permissible level by the EU standards (0.2 mg kg-1); Cu concentrations were 111 mg kg-1, 5 times the EU Standard (20 mg kg-1); concentrations of Pb were 6.77 mg kg-1, over 22 times the permissible levels allowed by both EU standards and UK guidelines (0.3 mg kg-1); Zn concentrations were 221 mg kg-1, over 4 times the guideline value (50 mg kg-1). The other plants (beans, maize, peppers and sugarcane) also contained concentrations of heavy metals above the permissible levels. Furthermore the concentrations observed in this study were higher than those reported by other workers who have examined vegetation from other contaminated sites. This study highlights the potential risks involved in the cultivation and consumption of vegetables on plots irrigated with sewage sludge, a practice which may place at risk the health of the urban population who consume these vegetables

EVALUATION OF FAO AQUACROP MODEL FOR ABILITY TO SIMULATE ATTAINABLE YIELDS AND WATER USE FOR FIELD TOMATOES GROWN UNDER DEFICIT IRRIGATION IN HARARE, ZIMBABWE

Crop simulation models have an important role in evaluating irrigation management strategies for improving agricultural water use. The aim of this study was to evaluate the AquaCrop model for ability to simulate water use and tomato ( Lycopersicon esculentum Mill.) fruit yields under deficit irrigation conditions. A fieldexperiment was conducted at Thornpark, University of Zimbabwe Research site over four seasons (2014 and 2017). The data collected for yield and water use were used to run and evaluate the performance of AquaCrop in predicting water use efficiency and fruit yield. Four treatments defined in relation to 100% of the crop water requirement (ETc) were simulated: T1 100% ETc; T2 80% ETc; T3 60% ETc and T4 50% ETc. The model performance was satisfactory, with a good correlation between the simulated and observed soil water content (SWC) and fruit yield (FY). All the statistical indicators (The Normalised Root Mean Square Error (R2), Root Mean Square Error (RMSE), Nush Sutcliffe Model Efficiency (EF), Pearson Correlation Coefficient (r), and Willmott\u2019s Index of Agreement (d)) used to compare the observed and predicted parameters, showed good performance; for example the EF showed values of 0.91 for SWC, the (r) showed values of 0.95 for SWC and a FY of 2.79 and 2.39 metric tonnes ha-1 for the simulated results. The results showed that the values of the simulated FY were consistent with the measured, with corresponding coefficients of determination (R2) of 0.93. The results revealed AquaCropisable to simulate the yield of tomato and the seasonal water requirements to an appreciable degree. However, it must be pointed out that the calibration of AquaCrop suffered from lack of measured data on the progress of crop canopy cover, which is an important parameter used in developing the model. The results obtained showed that AquaCrop can be used effectively in simulating tomato production under deficit irrigation and, therefore, it can be used as a decision-making tool for irrigation management of tomatoes in Zimbabwe.Les mod\ue8les de simulation de cultures jouent un r\uf4le important dans l\u2019\ue9valuation des strat\ue9gies de gestion de l\u2019irrigation pour am\ue9liorer l\u2019utilisation de l\u2019eau agricole. Le but de cette \ue9tude \ue9tait d\u2019\ue9valuer la capacit\ue9 du mod\ue8le AquaCrop \ue0 simuler l\u2019utilisation de l\u2019eau et les rendements en fruits de la tomate (Lycopersicon esculentum Mill.) dans des conditions d\u2019irrigation d\ue9ficitaire. Une exp\ue9rience sur le terrain a \ue9t\ue9 men\ue9e \ue0 Thornpark, site de recherche de l\u2019Universit\ue9 du Zimbabwe pendant quatre saisons ( 2014 et 2017). Les donn\ue9es collect\ue9es pour le rendement et l\u2019utilisation de l\u2019eau ont \ue9t\ue9 utilis\ue9es pour ex\ue9cuter et \ue9valuer la performance du mod\ue8le d\u2019AquaCrop dans la pr\ue9diction de l\u2019efficacit\ue9 de l\u2019utilisation de l\u2019eau et du rendement en fruits. Quatre traitements d\ue9finis par rapport \ue0 100\ua0% des besoins en eau des cultures (ETc) ont \ue9t\ue9 simul\ue9s. : T1 100\ua0% ETc\ua0; T2 80\ua0% ETc\ua0; T3 60\ua0% ETc et T4 50\ua0% ETc. Les performances du mod\ue8le \ue9taient satisfaisantes, avec une bonne corr\ue9lation entre la teneur en eau du sol (SWC) simul\ue9e et observ\ue9e et le rendement en fruits (FY). les indicateurs statistiques (l\u2019erreur quadratique moyenne normalis\ue9e (R2), l\u2019erreur quadratique moyenne (RMSE), l\u2019efficacit\ue9 du mod\ue8le de Nush Sutcliffe (EF), le coefficient de corr\ue9lation de Pearson (r) et l\u2019indice de concordance de Willmott (d) utilis\ue9s pour comparer les param\ue8tres observ\ue9s et pr\ue9dits, ont montr\ue9 de bonnes performances\ua0; par exemple, l\u2019EF a montr\ue9 des valeurs de 0,91 pour SWC, le (r) a montr\ue9 des valeurs de 0,95 pour SWC et un AF de 2,79 et 2,39 tonnes m\ue9triques ha-1 pour les r\ue9sultats simul\ue9s. Les r\ue9sultats ont montr\ue9 que les valeurs du FY simul\ue9 \ue9taient coh\ue9rentes avec les mesures, avec des coefficients de d\ue9termination (R2) correspondants de 0,93. Les r\ue9sultats ont r\ue9v\ue9l\ue9 que le modele d\u2019AquaCrop est capable de simuler le rendement de la tomate et les besoins saisonniers en eau \ue0 un degr\ue9 appr\ue9ciable. Cependant, il faut souligner que le calibrage du mod\ue8le \u2018AquaCrop a souffert du manque de donn\ue9es mesur\ue9es sur l\u2019\ue9volution de la couverture v\ue9g\ue9tale, qui est un param\ue8tre important utilis\ue9 dans l\u2019\ue9laboration du mod\ue8le. Les r\ue9sultats obtenus ont montr\ue9 que mod\ue8le \u2018AquaCrop peut \ueatre utilis\ue9 efficacement pour simuler la production de tomates sous irrigation d\ue9ficitaire et, par cons\ue9quent, il peut \ueatre utilis\ue9 comme outil d\u2019aide \ue0 la d\ue9cision pour la gestion de l\u2019irrigation des tomates au Zimbabwe

African Leafy Vegetables for Improved Human Nutrition and Food System Resilience in Southern Africa: A Scoping Review

The economic potential of African leafy vegetables (ALVs) remains obscured by a poorly developed value chain. This scoping review assembled and examined scattered knowledge generated on ALVs across southern Africa, focusing on production, processing, marketing, and consumption. Two electronic databases (Scopus and Web of Science) were screened, and a total of 71 relevant studies were included and evaluated. The review provides a state of the art on knowledge related to utilisation of ALVs across the entire value chain. The findings show that functional properties are of prime importance in the production and consumption of ALVs. However, the lack of improved germplasm and a non-existent seed supply system are significant production bottlenecks. Pests and diseases affecting the productivity of ALVs remain mostly unexplored. Sun-drying and boiling were the most reported post-harvest processing methods, suggesting that traditional processing methods are still prominent. Many studies also confirmed the predominance of informal marketsin the trading of ALVs as they fail to penetrate formal markets because of poor product positioning and exclusion from produce demand and supply forecasts. The inception of cultivar development,mechanised processing methods, and market linkages will enhance the profitability of ALVs in the region. This review enhances the gaining of insight into the state of different value chain componentswill assist in upscaling production, value addition of products, and enhance marketing efficiency. There is a great opportunity for basic and applied research into ALVs