Dietary inclusion of Tenebrio molitor larvae meal: Effects on growth performance and final quality treats of blackspot sea bream (Pagellus bogaraveo)

The purpose of this study was to investigate nutritional and phytochemical composition of Henicus whellani Chopard, a seasonally occurring ground-dwelling cricket consumed in south-eastern Zimbabwe. Insects were sampled from four quadrants (approximately 100m2) in one representative site (approximately 3000m2) in Bikita District, and were hand-picked or dug out from burrows in a manner similar to traditional insect-harvesting practices. Proximate composition using whole-dried insects and bioactive components using dried pulverized material were analysed using standard procedures. The proportional nutrient composition was 53.6% crude protein, 4.3% fat, 13.4% ash, 10.6% crude fibre, 4.0% carbohydrate and 268.3 kcal/100 g energy. Phenolics, tannins, alkaloids, cyanogenic glycosides, oxalates, saponins and flavonoids were present in the extracts of insects. The quantities of saponins (53.3 mg/g) and alkaloids (52.3 mg/g) were higher than those of other phytochemicals, with the quantity of tannins (0.168 mg/g) being the lowest. Radical-scavenging capacity determined using di(phenyl)-(2,4, 6-trinitrophenyl)iminoazanium (or 2,2-diphenylpicrylhydrazyl) and methanol extracts was 42%, which is lower than those of the standards. This study shows that H. whellani provides potential nutritional benefits in terms of protein, fibre and flavonoid contents. The relatively high ash content compared with that from other edible insects indicates a rich source of minerals such as calcium, iron, magnesium, phosphorus and potassium. However, the presence of saponins, oxalates and tannins could be a limitation and requires further studies. There is a need to evaluate the bioaccessibility of the nutrients and the safety of bioactive compounds in relation to human consumption.

Nutrient and anti-nutrient composition of Henicus whellani (Orthoptera: Stenopelmatidae), an edible ground cricket, in south-eastern Zimbabwe

Fish are a nutrient rich food but highly perishable due to its high water activity, protein content, neutral pH and presence of autolytic enzymes. This explains why fresh fish quality deteriorates rapidly if not properly stored after catch such as use of low temperature. The implication is that delayed processing of fresh fish negatively influences consumer taste of fish. Further, fresh fish that are not processed on time lose nutrients due to spoilage. In Malawi, most fresh fish are sold in the open due to lack of storage facilities such as refrigerators – a condition that accelerates spoilage of fish. This study was carried out to assess the effect of delayed processing on nutrient composition, pH level and organoleptic quality of pond raised tilapia - Oreochromis shiranus which is the commonest grown tilapia in Malawi. Thirty freshly pond harvested O. shiranus fish (average weight 100g) were cleaned then deep fried in edible cooking vegetable oil at time intervals of 0, 6 and 12 hours from catch and stored at ambient temperature. A pre-trained sensory evaluation panel consisting six members described changes in the sensory quality of the fresh and fried fish at every sampling time interval. Crude protein, crude fat, ash, moisture content and pH were also determined at each sampling time. Determined crude protein and crude fat decreased while ash content increased with storage time though these were not significantly different from baseline (P>0.05). Moisture content decreased from 0 (fresh) to 6 hours then increased again up to 12 hours of storage. Ash and moisture content correlated positively (0.93 and 0.79% respectively), whilst crude protein, crude fat and pH were negatively correlated (-0.91, -0.05 and -0.97, respectively) to sensory quality demerit scores. pH decreased from 5.94 at 0 hours to 5.92 after 6 hours then increased sharply to 5.98 after 12 hours of ambient fish storage. Consumers started to significantly (P<0.05) dislike the fish after 7 hours and eventually rejected the samples after 12 hours of ambient storage time. The study recommends that for optimum consumer satisfaction and nutritional benefit, fresh O. shiranus should be processed at most 7 hours after harvesting. Key words : Nutrients, taste, Tilapia, ambient storage

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Effect of delayed processing on nutrient composition, pH and organoleptic quality of pond raised tilapia (Oreochromis shiranus) stored at ambient temperature

The processing and preservation processes are necessary to guarantee the microbiological, technological, organoleptic and nutritional qualities of fish. This article describes the technological (fish flesh composition, fish flesh evolution after capture, evisceration, filleting, water content, water holding capacity and pH), organoleptic (fish freshness state, color and aspect, flavor, texture), hygienic and nutritional qualities of fish and their variation factors. The processing and preservation processes of fish (refrigeration, freezing, smoking, salting and drying) were described and finally, these processes impact on fish sensory, microbiological, technological and nutritional qualities is reported. The knowledge of processing and preservation processes as well as the control of variation factors will improve the hygienic, technological, organoleptic and nutritional qualities of fish useful for human consumption. Resume Les procedes de transformation et de conservation sont necessaires pour garantir les qualites microbiologiques, technologiques, organoleptiques et nutritionnelles des poissons. Cet article decrit les qualites technologiques (composition de la chair des poissons, evolution de la chair de poisson apres la capture, evisceration, filetage, teneur en eau et la capacite de retention d’eau et le pH), organoleptiques (etat de fraicheur des poissons, couleur et aspect, flaveur, texture), hygieniques et nutritionnelles des poissons et leurs facteurs de variation. Les procedes de conservation et de transformation des poissons (refrigeration, congelation, fumage, cuisson, salage et sechage) ont ete ensuite decrits et enfin, l’impact de ces procedes sur les qualites sensorielles, microbiologiques, technologiques et nutritionnelles des poissons est expose. La connaissance des procedes de transformation et de conservation et la maitrise des facteurs de variation au profit de ces procedes serviront a ameliorer les qualites hygieniques, technologiques, organoleptiques et nutritionnelles des poissons utiles pour la consommation humaine.

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Qualité de la Chair des Poissons : Facteurs de Variations et Impacts des Procédés de Transformation et de Conservation

Freezing and thawing are heat transfer processes, involving chemical changes which may greatly affect product quality. Due to sparse literature on freeze-thawed cycles and its effects on soups quality, the effect of freeze-thaw cycles on the nutritional quality of selected Nigerian soups has to be investigated. Soups (Ila, Ewedu, Ogbono, and Kuka) were prepared using standard recipes. The soups were packaged in plastic and aluminum containers, frozen at -20°C, and thawed with microwave oven, hot water (100°C), and at ambient condition for four cycles of 5-day interval. After each cycle, chemical compositions of the samples were determined using AOAC methods. Data were analyzed using ANOVA at P = 0.05. Moisture, protein, fat, crude fiber, ash, and carbohydrate contents of the freeze-thawed soups were 63.6-88.6%, 3.6-8.8%, 1.0-6.1%, 0.8-1.2%, 1.8-4.6%, and 0.9-15.6%, respectively. Mineral contents were iron (5.0-6.8 mg/100 g), calcium (68.1-190.8 mg/100 g), sodium (144.4-231.7 mg/100 g), potassium (200.4-302.1 mg/100 g), and phosphorus (228.0-337.2 mg/100 g). Vitamins were vitamin A (29.5-59.9 mg/100 g), vitamin B (10.1-36.4 mg/100 g), and vitamin E (28.4-90.2 mg/100 g). Microwave-thawed plastic soups had limited nutritional losses when compared with other thawing methods, and should not be extended beyond the third cycle because of increasing reduction in fat and protein, indicating deterioration.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/fsn3.271

Effect of freeze-thaw cycles on the nutritional quality of some selected Nigerian soups.

Microbiological analysis of Tilapia guineensis was assessed at two ice stored temperatures, -18 and 4°C, for 4 weeks. Bacteria and fungi counts decreased from 7.9 × 103 to 5.4 × 101 cfu/g for bacteria and 6.2 × 103 to 3.2 × 102 cfu/g for fungi in the samples stored at -18°C, while for the samples stored at 4°C, an increase was shown in counts from 7.9 × 103 to 7.6 × 107 cfu/g for bacteria and 6.2 × 103 to 6.8 × 104 cfu/g for fungi. Pseudomonas, Staphylococcus, Bacillus,Proteus, Micrococcus and Aeromonas sp. were the bacteria species isolated before cold storage, while only Pseudomonas, Staphylococcus, Bacillus andProteus sp. were isolated from samples stored at -18°C. The same organisms isolated before cold storage were also isolated for samples stored at 4°C. Fungal species isolated before cold storage include: Cladiosporium, Aspergillus andFusarium sp. All these fungi species were also isolated from samples stored at -18°C. Cladiosporium, Pichia, Aspergillus and Fusarium sp. were isolated from samples stored at 4°C. The level of bacteria and fungal growth in fish stored at 4°C temperature exceeded the acceptable microbiological limits (102/g for moulds and 103/g for bacteria). However, the pH of fish was found to increase in the two stored temperatures. It was within the alkaline range in the -18°C stored samples, but within the acidic range in the 4°C stored samples. There were significant differences (P<0.05) in the microbiological composition of the ice stored Tilapia guineensis within the same temperature and between the two temperatures. The quality of the 4°C stored sample deteriorated faster than that of the -18°C. Thus, storage temperature and duration have effects on the quality of stored fish.

	 

	Key words: Tilapia guineensis, fish, sample, bacteria.

Microbiological assessment of stored Tilapia guineensis

The organoleptic and proximate analysis of Tilapia guineensis were assessed at two stored temperatures, -18oC and 4oC for 4 weeks. Graded results revealed a general decline in organoleptic properties such as colour, texture, freshness, and taste of the fishes stored at the two temperatures. Proximate analysis revealed a reduction in crude protein and lipid contents and increases in ash and fibre content of the fish at the two storage temperatures. Moisture content decreased in the samples stored at -18oC but increased in the 4oC stored samples. pH of fish was found to increase in the two stored temperatures. It was within the acidic range in the -18oC stored sample but the alkaline range in the 4oC stored samples. There were significant differences ‘‘P<0.05’’ in the organoleptic and proximate composition of the ice stored Tilapia guineensis within the same temperature and between the two temperatures. The quality of the 4 o C stored sample deteriorated faster than that of the 18oC. Thus storage temperature and duration have effects on the nutritional quality of stored fish.

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Oriakpono Obemeata

Papers

Microbiological assessment of stored Tilapia guineensis

Organoleptic Assessment and Proximate Analysis of Stored Tilapia guineensis