Role of Biogenic Amines in Protein Foods Sensing: Myths and Evidence

Myriads of sensors have been proposed to signal the spoilage of a piece of meat. It is assumed and taken for granted that biogenic amines, BAs, harmful by-product indicating the last phase of degradation, must be present in the volatilome developed over the decaying meat. This chapter aims to clearly explain BAs’ role in protein food spoilage: undoubtedly produced inside the meat, never present in the headspace, where sensors are displayed. The BAs presence in the headspace represents a sort of myth. It is plenty of evidence that BAs cannot be present in the volatilome over the meat. The BAs’ volatility is pH-dependent. As shown by their protonation constants, the strongly buffered pH of proteinaceous food prevents their vapour phase transition. The chemical analyses made at the same degradation time, on the meat and the headspace above the meat, corroborate the real composition of the volatilome, demonstrating the BAs absence. The sensors here described, designed on volatilome evidence, succeed to follow the entire process, from the SAFE condition to the WARNING and the HAZARD. The final prototype works reliably on real protein foods (i.e. chicken, beef pork and fish), not enriched and stored at the home condition.

A comparative study on the nutritional and microbial safety of fresh ‘Wara’ hawked in Ilorin and Ogbomoso towns

Malnutrition resulting from low protein intake is one of the nutritional problems facing most developing countries including Nigeria. Most proteinaceous food sources are costly and in short supply. ?Wara? is a proteinaceous ready to eat food product made by curdling milk. It does not normally undergo any further safety treatments before consumption. Frequent hawking on our major streets and roads calls for determination of the safety of these products. ?Wara? samples sourced from four different locations each at Ilorin, Kwara State and at Ogbomoso, Oyo State respectively, were analysed for nutritional and microbial safety. Proximate composition of the samples over the period of storage showed that moisture content and carbohydrates increased from 59.69% to 72.00% and from 2.39% to 11.39% respectively, while protein, fat and ash contents reduced from 22.20% to 10.80%, 15.80% to 3.62% and from 2.99% to 0.25%, respectively. Microbial and fungal counts ranged from 2.0 X 102cfu to 6.3 X 105cfu and from 2.0 X 102cfu to 7.1 X 105 cfu, respectively. Klebsiellaand Salmonella species, Escherichia coli and some fungiwere isolated. The study revealed that some of the hawked cheeses were not safe for consumption. Attributable reasons were unhygienic practices of the hawkers or producers and/or lack of requisite preservatives.

Nutritional Effects on Vitellogenesis in Species of Drosophila

A comparative study of vitellogenesis in response to feeding was made in females of three species of the genus Drosophila, belonging to different species groups. The process of vitellogenesis, although conservative, shows significant differences in species phylogenetically distant to D. melanogaster (Meigen). Females of D. virilis (Sturtevant) and D. hydei (Sturtevant) enter vitellogenesis and produce mature eggs only after proteinaceous food intake, but not under sucrose diet, while D. melanogaster females are able to support oocyte development upon maturity under sucrose diet. Electrophoretic analysis of the hemolymph of D. virilis and D. hydei starved or sucrose-fed females shows yolk protein synthesis at trace amounts. Interestingly, in the absence of proteinaceous food one or two other polypeptides of slightly higher molecular mobility than vitellogenins (but not vitellogenins) are produced, indicating a condition of starvation shock. These polypeptides are not detected in the hemolymph of either starved or sucrose-fed females D. melanogaster in which the vitellogenins are produced at low rate or significant amount, respectively. The results indicate that starvation affects ovarian yolk protein synthesis as well. Conversely, starvation does not directly affect the process of yolk protein uptake by the developing oocytes.