Mass-rearing of the redlegged ham beetle, Necrobia rufipes De Geer (Coleoptera: Cleridae) for laboratory research

A new protocol for mass-rearing the redlegged ham beetle, Necrobia rufipes De Geer, in the laboratory is described, that facilitates the production of large numbers of insects with minimal handling. A culture medium comprised of finely ground (150 μm) dried fish, dry dog food and pieces of dried cured ham was tested on N. rufipes. This rearing medium produced significantly larger population numbers when compared with a range of published and unpublished methods. When reared on this medium with initial colonies of 200 mixed sex adult beetles, there was more than a three-fold increase in N. rufipes adult populations from the original numbers over a 7-8 week period. This simple procedure minimizes cannibalism as the larvae were shifted into glass vials for pupal cell formation.     

Current technologies and new insights for the recovery of high valuable compounds from fruits by-products

The recovery of high valuable compounds from food waste is becoming a tighten issue in food processing. The large amount of non-edible residues produced by food industries causes pollution, difficulties in the management, and economic loss. The waste produced during the transformation of fruits includes a huge amount of materials such as peels, seeds, and bagasse, whose disposal usually represents a problem. Research over the past 20 years revealed that many food wastes could serve as a source of potentially valuable bioactive compounds, such as antioxidants and vitamins with increasing scientific interest thanks to their beneficial effects on human health. The challenge for the recovery of these compounds is to find the most appropriate and environment friendly extraction technique able to achieve the maximum extraction yield without compromising the stability of the extracted products. Based on this scenario, the aim of the current review is twofold. The first is to give a brief overview of the most important bioactive compounds occurring in fruit wastes. The second is to describe the pro and cons of the most up-to-dated innovative and environment friendly extraction technologies that can be an alternative to the classical solvent extraction procedures for the recovery of valuable compounds from fruit processing. Furthermore, a final section will take into account published findings on the combination of some of these technologies to increase the extracts yields of bioactives.     

Physicochemical stability of antilisterial proteins from P. polymyxa Kp10 as potential food biopreservative

Listeria monocytogenes has continuously become a significant threat to consumers worldwide. The use of chemical-derived preservatives that are commonly associated with safety and nutritional issues has prompted the use of natural-based preservatives as a better alternative. Many bacterial strains including Paenibacillus polymyxa Kp10 have been reported to produce various antimicrobial proteins and compounds that are considered more natural. However, their stability in various physicochemical conditions should be examined before being applied in various types of food. In this study, the stability of four previously identified antilisterial proteins in P. polymyxa Kp10 upon exposure to several physicochemical conditions was examined. More than 80% residual antilisterial activity is conserved upon heat and proteinase K treatment. But, sensitivity to 24 h trypsin digestion has been observed. P1 and P2 proteins (histone-like DNA binding proteins HU) were sensitive to alkaline pH (pH 10-12) as compared with other proteins. More than 70% and 97% residual antilisterial activity were recovered after incubation in raw beef homogenates and simulated meat gravy model, respectively. However, the antilisterial activity of most proteins was highly compromised in chicken and salmon meat homogenates, and UHT cow milk. Inoculation of these proteins into Listeria-contaminated simulated meat gravy showed that all proteins exerted a bactericidal action against L. monocytogenes. P1 and P2 shared almost similar antilisterial activity rates, while P4 was the most potent antilisterial protein. The findings in this study could provide important preliminary data for future applications of these proteins as preservative in food products especially beef-based meat products.     

Phospholipid composition of liver in rats fed high levels of 13-cis retinoic acid

The composition of liver phospholipids was studied in rats fed for 4 weeks diets containing 0, 100 or 300 mg 13-cis retinoic acid per kg diet. There was a significant decrease in phosphatidylcholine content, whereas the levels of phosphatidylethanolamine were slightly increased in liver phospholipids of rats fed 13-cis retinoic acid. The fatty acid composition of total phospholipids, PC, PE, and PI+PS fractions revealed a general increase in the levels of 18∶2 and 20∶3ω6, whereas the levels of 20∶4ω6 and C₂₂ fatty acids were reduced in most of the hepatic phospholipids isolated from rats fed 13-cis retinoic acid containing diets. A decrease in the double-bond index of fatty acids was also observed in phospholipids of rats fed 13-cis retinoic acid. The data suggest that high levels of 13-cis retinoic acid may possibly be influencing the activities of microsomal desaturating and chain-elongating enzymes in the liver.