Changes in fatty acids during storage of artisanal-processed freshwater sardines (Rastrineobola argentea).

For ages, indigenous small fish species have been important in food and nutritional security of poor communities in low income countries. Freshwater fish, in particular fatty fish species are attracting a great attention because they are good sources of health promoting long chain omega-3 fatty acids. Docosahexaenoic acid (DHA, C22:6n-3), Docosapentaenoic acid (DPA, C22:5n-3) and eicosapentaenoic acid (EPA, C20:5n-3) are the main omega-3 PUFAs known to confer health benefits in humans if consumed in required amounts. While nutritionally valued, omega-3 PUFAs in fish are susceptible to oxidative damage during processing, transportation and subsequent storage. Lake Victoria sardines (Rastrineobola argentea), are rich source of chemically unstable omega-3 fatty acids DHA, DPA and EPA. Traditionally, sardines are preserved by sun drying, deep frying and smoking. Sardine products are transported, stored and marketed at ambient temperatures. Generally, uncontrolled and higher temperatures are known to increase vulnerability of polyunsaturated fatty acids to oxidation which in turn results into loss of nutritional and sensory qualities. This study investigated changes of fat acids in sun dried, deep fried and smoked sardines during storage. Lipolysis and the progressive hydroperoxides formation were monitored by free fatty acids (FFAs) and peroxide value (PV) respectively. None volatile secondary products of lipid oxidation were measured by thiobabituric acid reactive substances (TBARS). Fatty acids were analyzed by gas chromatography with a flameionization detector (GC-FID). Deep fried sardines maintained the lowest and apparently stable PV, TBARS and FFAs. Proportions of saturated fatty acids and polyunsaturated fatty acids decreased with time while that of monounsaturated fatty acids increased. Omega-3 fatty acids EPA, DPA and DHA decreased with increase in storage time. In 21 days of storage, DHA was oxidized beyond detectable levels in all sardine products. Gradual increase in FFAs in sun dried sardines was suggestive of lipid hydrolysis induced by enzymes.

Dry-heat processing at different conditions impact the nutritional composition and in vitro starch and protein digestibility of immature rice-based products.

Immature grain represents a precious nutritional source in many rural Africa areas. To optimize processing of immature rice into pepeta (a traditional rice-flakes produced from immature rice grains), immature rice (TXD306 variety) harvested at 18 and 26 days after 50% heading were processed in the laboratory under different soaking (0 and 12 h) and roasting temperature (80, 100 and 120 °C) regimes. Riboflavin, nicotinic acid, nicotinamide and iron concentration increased with severity of roasting temperature, while thiamine has an opposite trend. Heating promoted the transformation of insoluble into soluble dietary fiber, increased lipid digestibility decreasing protein one, which showed the highest value when rice was roasted at 100 °C. Soaking before roasting significantly increased moisture and iron content while slightly increased riboflavin, nicotinic acid and nicotinamide when compared to unsoaked products. Among roasted products, starch digestibility increased with roasting temperature. Microstructure analysis indicated a complete loss of cell wall integrity in cooked rice, determining a complete starch and protein digestion while this is delayed in raw rice and roasted products. We concluded that roasting at 100 °C is the optimum temperature to produce pepeta of the highest protein digestibility and low starch digestibility. Soaking before roasting at 120 °C is best when retaining micronutrients is considered.

Utilization of Pepeta, a locally processed immature rice-based food product, to promote food security in Tanzania.

Consumption of pepeta, a traditionally processed immature rice product, is common in Tanzania, where it contributes to food security as an early rice food i.e. when there is no other food available at the household while the crops in the field not yet fully ripe. Many production steps are needed to guarantee a consistent, good quality pepeta product, and this hinders its utilization in other rice-growing sub-Saharan regions. This study aims to gain insight into the pepeta processing knowledge and final product, and assess variations in the processing conditions and parameters across the study area. A survey among 257 Tanzanian processors and consumers revealed that the pepeta product is widely known, rated second (73.5% respondents) as rice-based food after wali (cooked white rice, (100%)) and linked to traditions of the communities in the study area. Harvest of immature rice grain, roasting, pounding, cleaning, and packing are the main process steps of pepeta production. Method of rice harvest, rice suitability for pepeta production after optimum harvest, dryness of grains and number of pounding as indicator to terminate roasting and pounding process respectively, and packaging materials used varied significantly across respondents in the study area. Reported criteria considered by respondents for product acceptability did not vary significantly across study area. The criteria include colour (76.5%), general appearance (60.8%), texture (64.7%) and taste (52.9%). Immature rice paddy and pepeta were sold at a higher price than mature rice paddy and white rice, respectively, which implies that options to facilitate pepeta processing through, for instance, standardization of processing conditions and parameters could lead to increased income.

Nutritional quality and in vitro digestion of immature rice-based processed products.

Rice is commonly consumed as fully mature grain, but immature rice is considered to have better nutrient and technological properties. This is attributed to changes in content and profile of nutritional and functional compounds during maturation. This study assessed the effect of maturity on nutrient content of rice grains, and in vitro digestibility of starch and protein, for immature rice grains of TXD306 and Lawama varieties. The effect of processing of immature rice into so-called pepeta, traditionally produced from immature rice grains and widely consumed in Tanzania, was studied as well. The results showed reductions in lipid, protein, ash, thiamine, nicotinic acid, nicotinamide, and soluble and insoluble dietary fibre contents during rice grain development. However, no effect of maturity on in vitro starch and protein digestibility was observed. The contents of protein, ash, lipid, nicotinamide, iron, zinc, and total, soluble and insoluble dietary fibre were higher in pepeta from both varieties than in the corresponding rice grains. Protein digestibility of pepeta flour was 58.9% higher than that of cooked rice for variety TXD306, and 73.8% higher for Lawama. Differential scanning calorimetry indicated that starch of processed immature rice was completely gelatinized whereas its susceptibility to digestion in vitro was slightly lower than for cooked rice, possibly due to the higher cellular integrity retained after processing. These results demonstrate that pepeta-type processing improves the nutritional properties of rice and its potential use as a snack or ingredient in cereal-based formulas.

Traditional Practices and Consumer Habits regarding Consumption of Underutilised Vegetables in Kilimanjaro and Morogoro Regions, Tanzania.

BACKGROUND: Wild vegetables serve an important purpose in the health and diet of many people residing in the rural areas. Various traditional practices associated with their processing and consumption are uncommon and unknown to the present generation, resulting to their underutilization. METHODS: Qualitative data were obtained through focus group discussions (FGDs), key informant interviews (KIIs), and participant observation. Using a checklist and questionnaire, a total of 120 individuals from 120 randomly selected households in Kilimanjaro and Morogoro regions were interviewed. Results. Underutilised indigenous vegetables from Morogoro and Kilimanjaro regions were investigated. Out of 40 vegetables, four underutilised vegetables (UVs), Sunga (Launea cornuta), Kikundembala (Vigna vexillata), Mokiki (Momordica foetida), and Inyiri (Basella alba), were identified, collected, and studied. Over 75% of respondents preferred UVs to exotic species, the likes of cabbage, amaranth, eggplant, pumpkin leaves, and spinach. It was further noted that with the existing myths and fads associated with consumption of UVs, as well as the widespread use of the exotic vegetable species among the modern generation, UVs' future demand is diminishing. CONCLUSION: There are many varieties of UVs in Morogoro and Kilimanjaro regions. However, the UVs are currently showing decreasing demand due to various reasons including difficulties in preparation, low palatability, and negative image to consumers; introduction of exotic species of vegetables was found to further suppress the use of UVs.

Micronutrients Potential of Underutilized Vegetables and Their Role in Fighting Hidden Hunger.

BACKGROUND: Innumerable underutilized vegetable (UV) species have been utilized as food and as folklore medicine since time immemorial. Such vegetables have been part and parcel of the food dishes, especially to the ancient rural and periurban dwellers. However, researchers and agricultural scientists have given little or no attention to such vegetables, as to what constitutes their potentials in curbing hidden hunger. To achieve the global Sustainable Development Goals, Tanzania needs to address the issue of food insecurity through the use of not only grains, fruits, and edible insects but also through embracing the UVs. The overall objective of this study was to screen the indigenous vegetables with nutritional and health claims from communities in Kilimanjaro and Morogoro regions. METHODS: Quantitative data were obtained by conducting laboratory nutrient and antinutrients composition analyses as per standard Association of Official Analytical Chemists (AOAC) methods. This was carried out to determine the moisture content, micronutrient, and antinutrients composition of the selected UVs. RESULTS: The nutritional and medicinal claims of the selected UVs mentioned during interviews were validated by data obtained from laboratory nutrient and antinutrients composition analyses. Chemical analyses revealed that vitamin A, B1, B2, B3, and C contents ranged from 2.50-6.67, 18.94-182.95, 0.18-0.76, 0.09-0.43, and 46.52-198.08 mg/100 g, respectively. Minerals, on the other hand, Ca, Fe, Mg, and Zn contents ranged from 60.28-421.03, 4.28-21.05, 191.12-1151.91, and 4.28-21.10 mg/100, respectively. Moisture content, oxalates, and phytates contents ranged from 78.59-95.49%, 1.28-3.15, and 1.64-6.18 mg/100 g, respectively. CONCLUSION: The findings from the study added credence to the selected UVs that they are rich sources of micronutrients and crucial in daily human diet to curb hidden hunger.

Traditions, beliefs and indigenous technologies in connection with the edible longhorn grasshopper Ruspolia differens (Serville 1838) in Tanzania.

BACKGROUND: Edible insects are an important source of food to many African populations. The longhorn grasshopper, Ruspolia differens (Serville 1838), commonly known as senene in Tanzania is one of the most appreciated edible insects by societies around Lake Victoria crescent. Senene is primarily an essential treat for the tribes around the lake, e.g., the Haya of Tanzania, Luo of Kenya and Baganda of Uganda. Despite its importance as a food item and appreciation as a delicacy, there are few studies dealing with culture, beliefs and indigenous technology in connection with the senene. The main objective of this study was to survey indigenous technologies, processing methods and traditions in relation to senene consumption among the Haya tribe in Kagera region of Tanzania. METHODS: Our ethnographic study was conducted through semi-structured interviews. A total of 51 locals, 26 females and 25 males aged 21 to 60 years were interviewed (with 3 female and 7 male key informants among them). Questions focused on cultures, beliefs and traditions towards senene consumption. Processing, preservation and shelf-life as well as nutritional knowledge were also investigated. RESULTS: Harvesting for household consumption was mainly done through wild collection. Traditionally made traps were mostly used for commercial harvesting. Deep frying was the most preferred processing method while smoking was the most preferred preservation method, with shelf-life of up to 12 months. Interesting traditions and taboos associated with senene consumption were identified, with men monopolising the insects as food by declaring the insects taboo for women and children. Deep fried senene in locally packed containers were mostly sold by street vendors, but also available from a variety of stores and supermarkets. CONCLUSION: Beyond being just an important traditional delicacy, senene is becoming increasingly popular, providing opportunity for local businesses. Indigenous technologies for harvesting, processing and preserving senene exist, but must be improved to meet food processing standards, thereby promoting commercialization. This carries economic potential essential for improving incomes and livelihoods of women and smallholder farmers, improving household level food security.

Effect of genotype and genotype by environment interaction on total cyanide content, fresh root, and starch yield in farmer-preferred cassava landraces in Tanzania.

High starch yield is the most important trait for commercialized cassava starch production. Furthermore, cyanide present in cassava roots poses a health challenge in the use of cassava for food. Cassava genotypes have varying maturity periods that are also environmental dependent. This study aimed at identifying suitable cultivars and optimum time of harvest to maximize starch production across three environments. The study found significant difference between genotypes, locations, harvest period, and all the interactions (P ≤ 0.001) for all traits analyzed. Kiroba recorded high starch yields of 17.4, 12.7, and 8.2 t ha-1 at Chambezi, Amani, and Magadu, respectively. Kilusungu recorded highest cyanide content of 300-400 ppm across all locations but Kiroba recorded highest values of 800 ppm, 15 months after planting at Chambezi. Genotype by environment (GGE) biplot analysis revealed that Kiroba was a superior cultivar in terms of starch yield. Kilusungu recorded highest cyanide content and average starch yield, therefore suitable for use in starch production. The study confirmed effect of genotype and genotype by environment interaction, Kiroba cultivar was superior in terms of starch yield and maximum starch yield was obtained at 9 months after planting. Nyamkagile and Kibandameno had the lowest cyanide content across all environments.