The production of phagostimulant and attractive volatile organic compounds (VOCs) by yeasts can be exploited to improve the efficacy of attract-and-kill formulations against the spotted wing drosophila (SWD). This study evaluated the persistence over one week of a yeast-based formulation under greenhouse conditions. Potted grape plants were treated with: (i) potato dextrose broth (PDB), (ii) PDB containing spinosad (PDB + S), and (iii) H. uvarum fermentation broth grown on PDB containing spinosad (H. u. + S). Laboratory trials were performed to determine the survival and the oviposition rate of SWD after exposure to treated leaves. Ion-exchange chromatography was performed to measure carbohydrates, sugar alcohols, and organic acids on leaf surfaces, while amino acids were assessed through liquid chromatography–mass-spectrometry. Additionally, the VOCs released by plants treated with H.uvarum were collected via closed-loop-stripping analysis and compared to those emitted by untreated leaves. A higher mortality was observed for adult SWDs in contact with H. uvarum containing spinosad compared to PDB containing spinosad. Generally, a decrease in the amounts of non-volatile compounds was observed over time, though numerous nutrients were still present one week after treatment. The application of the yeast-based formulation induced the emission of VOCs by the treated leaves. The concentration of 2-phenylethanol, one of the main VOCs emitted by yeasts, decreased over time. These findings describe the presence of potential phagostimulants and compounds attractive to SWD in a yeast-based attract-and-kill formulation and demonstrate the efficacy of the formulation over one week.

In recent years, there has been a growing interest in the development of health-promoting and disease-preventing functional foods. Beetroot is a promising vegetable because of its outstanding antioxidant activity, vivid colour, and content of bioactive compounds. In the present study, the quality of pure beetroot and apple juices as well as that of their mixture was evaluated by measuring changes of colour, betalain content, and antioxidant activity during processing and storage. No perceivable colour changes of the beetroot juice were observed after adding apple juice up to 85% of the total amount. However, the antioxidant activity was proportionally reduced with the addition of apple juice. Pasteurization negatively affected the content of betalains but did not influence the antioxidant activity. Storage led to colour modifications and reduction of betalains and antioxidant activity. Through preliminary shelf-life studies, a durability of 65 days at room temperature for apple and beetroot juice blends was calculated. The novelty of this study lies in an extended description of physico-chemical characteristics of a fresh apple and beetroot blended juice obtained from local products, in the study of the effects of processing and storage on its quality, and in the estimation of its shelf-life after storage at different temperatures.

Yeasts constitute a dietary source for the spotted wing drosophila (SWD) and produce compounds that attract these flies. The study of the chemical composition of the yeast communities associated with SWD should therefore help to understand the relationship between the biology of the insect and the yeast’s metabolism. In the present study, the lipidome of five yeast species isolated from grapes infested by SWD (three Hanseniaspora uvarum strains, Candida sp., Issatchenkia terricola, Metschnikowia pulcherrima and Saccharomycopsis vini) and a laboratory strain of Saccharomyces cerevisiae was explored using an untargeted approach. Additionally, the lipid profile of two species, S. cerevisiae and H. uvarum, which were reported to elicit different responses on SWD flies based on feeding and behavioral trials, was compared with a chemical enrichment approach. Overall, 171 lipids were annotated. The yeast species could be distinguished from each other based on their lipid profile, except for the three strains of H. uvarum, which were very similar to each other. The chemical enrichment analysis emphasized diversities between S. cerevisiae and H. uvarum, that could not be detected based on their global lipid profile. The information concerning differences between species in their lipidome may be of interest to future entomological studies concerning the yeast-insect interaction and could help to explain the responses of SWD to diverse yeast species.

Several fresh-cut apple snacks are available on the market, and their color is highly relevant for consumers. As apple slices brown very quickly after cutting, dipping them in an antioxidant solution for a few minutes is common to avoid this phenomenon. However, this procedure has some limitations. Using the same solution for several immersion cycles over several hours can lead to cross-contamination and microbial growth. In addition, osmotic exchange phenomena in the immersion tank lead to a reduction in the concentration of the active ingredients of the antioxidant solution over time, which requires continuous readjustment of the concentrations. These aspects, together with the large quantities of exhausted antioxidant solution to be disposed of, are limiting factors that drive the search for alternative and more sustainable methods than dipping. In this work, a comparison between a conventional dipping treatment of fresh-cut apples and spraying at increasing volume of antioxidant solution was performed. Color, considered as the quality reference parameter, was visually assessed (occurrance of dark spots) and CIE Lab colorimetric indices were measured over a five-day experimental period. Based on dark spots and the changes in brightness (Δ L*), hue angle (Δ h) and chroma (Δ C*), some of the spraying treatments applied were found to be comparable to dipping in controlling browning. For all treatments, high intra- and inter-batch variability and within slices of the same apple was observed concerning both instrumental data and dark spots development, indicating that further investigation is needed to validate this result and to apply this procedure at an industrial level.

Juice extracted from unripe grapes during the thinning stage, also named "verjuice", has a very low pH and sour taste, making it a sustainable substitute for acidifying additives in pasteurized preserves, such as elderflower syrup. This traditional beverage is very popular due to its pleasant taste and health-promoting properties, including a high amount of phenolics. In this study, the suitability of verjuice as an acidifier in elderflower syrup was assessed and compared with citric acid, indicated in the label as E330. Chemical characterization, antioxidant activity and sensory characteristics of elderflower syrups were investigated. The product obtained with verjuice exhibited higher antioxidant activity compared to the one acidified with citric acid, despite having the same total polyphenol amount. Sensory tests indicated no significant difference in the overall liking between citric acid and verjuice acidified syrups, even though they were recognizably different. In conclusion, verjuice can be used as an acidifying ingredient in elderflower processing, with benefits regarding the reuse of an agrifood side product thereby lowering waste, creating new value from regional products, and allowing to obtain a „clean label”.