Salinity of nutrient solution influences the shelf-life of fresh-cut lettuce grown in floating system

Quality, microbiological and enzymatic characteristics of fresh-cut lettuce (Lactuca sativa var. longifolia, ‘Duende’), grown in floating system with three electrical conductivities of nutrient solutions (2.8, 3.8 and 4.8 mS cm^?1), were investigated in order to evaluate the effect of salinity on product shelf-life during cold storage (9 d at 4 °C). Pre-harvest salinity of 3.8 and 4.8 mS cm^?1 improved the properties of fresh-cut lettuce, since CO₂ production was reduced with a subsequent control of the decay process. Fresh-cut processing caused an activation of polyphenol oxidase and peroxidase; in all cases the product obtained by salinity treatments was less subject to oxidase activity and browning phenomena during storage. Increased salinity reduced the number of mesophilic bacteria and of moulds and yeasts, assessed by plate counts on different culture media; in contrast, Enterobacteriaceae levels were unaffected by pre-harvest treatments. The research demonstrated that an increase in nutrient solution electrical conductivity, through the use of floating system, affects fresh-cut lettuce characteristics, improving shelf-life of the product.     

Postharvest efficacy of resistance inducers for the control of green mold on important Sicilian citrus varieties

Journal of Plant Diseases and Protection - The disease reducing activity of acibenzolar-S-methyl (ASM), chitosan and β-aminobutyric acid (BABA) against postharvest green mold (GM) of citrus...     

Bioactivity Improvement of <Emphasis Type="Italic">Olea europaea</Emphasis> Leaf Extract Biotransformed by <Emphasis Type="Italic">Wickerhamomyces anomalus</Emphasis> Enzymes

Olive leaves represent a quantitatively significant by-product of agroindustry. They are rich in phenols, mainly oleuropein, which can be hydrolyzed into several bioactive compounds, including hydroxytyrosol. In this study, water extract from olive leaves ‘Biancolilla’ was analyzed for polyphenol profile, DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity and protective effect on differentiated Caco-2 cells. The efficacy of two enzymatic treatments in promoting the release of bioactive phenols was investigated: a) enzymatic extract from Wickerhamomyces anomalus, characterized by β-glucosidase and esterase activities; b) commercial β-glucosidase. Composition and bioactivity of the resulting extracts were compared. The results showed that the yeast-treated extract presented hydroxytyrosol content and DPPH radical scavenging activity comparable to those obtained using commercial β-glucosidase; however, it was showed the additional presence of hydroxycinnamic acids. In experiments on Caco-2 cells, the leaf extracts promoted the recovery of cell membrane barrier at different minimum effective concentrations. The high specificity of W. anomalus enzymatic extract may represent an effective tool for the release of bioactive phenols from olive by-products.     

Role of different factors affecting the formation of 5-hydroxymethyl-2-furancarboxaldehyde in heated grape must

The influence of concentration and water activity (a(w)) on the formation of 5-hydroxymethyl-2-furancarboxaldehyde (HMF) in thermally treated grape must was evaluated. Must was cryoconcentrated and then heated to study the pure effect of sugar concentration. Moreover, NaCl was added to the must to lower a(w), maintaining the same sugar concentration, with the purpose of evaluating the pure effect of a(w). Finally, the influence of minimal pH changes on the formation of HMF was evaluated by means of a model solution. The results showed that a(w) and sugar concentration are both determinant in the formation of HMF in grape must. Sugar concentration influences the reaction by supplying substrates; low a(w) enhances the formation of HMF by changing the equilibrium in the dehydration step of the reaction.