Potential agrifood application of seriguela (Spondias purpurea L.) residues extract and nanoZnO as antimicrobial, antipathogenic and antivirulence agents

The impact of phytopathogenic microorganisms in several crops causes significant losses in agrifood industry, spoilage throughout food chain and storage. Nanoparticles and plant extracts have been highlighted by their antimicrobial properties applied in food packaging, agriculture, drug delivery systems and other medical approaches. Over the past few years, this group have studied the application of ZnO nanoparticles and agroindustrial wastes in edible food coatings/films. This study aimed to evaluate active characteristics from the extract of seriguela processing wastes and nanoZnO regarding to their inhibitory activity against bacterial pathogenicity and virulence systems TTSS (Type Three Secretion System) and QS (Quorum Sensing) for Pseudomonas savastanoi. Also, antibacterial action (inhibition area) against species of Curtobacterium, Clavibacter, E. coli, Xanthomonas and Serratia, and antifungal against Botrytis cinerea (reduction in colony size). The 60% extract inhibited the activation of QS and TTSS system in 20.26% and 13.54%, respectively; while nanoZnO at 3% reduced 46.77% QS and increased 302.88% TTSS. Extract without dilution inhibited the growth of Clavibacter michiganensis pv michiganensis (Gram-positive) and Xanthomonas phaseoli (Gram-negative), inhibitory zone of 94.25 mm2 and 452.39 mm2 respectively. The latter also being inhibited by nanoZnO 1 and 2% (138.23 mm2) and 3% (275.67 mm2). Pure extract inhibited 17.38% growth of fungal colony and nanoZnO (1 and 3%) in 33.08%. Finally, the active agents studied showed to be promising in the prevention of phytopathogenic diseases and consequently economic losses, food films/coatings and the extract as a biopesticide, reducing the environmental impact.

Enhancing or Inhibitory Effect of Fruit or Vegetable Bioactive Compound on Aspergillus niger and A. oryzae

Fruit and vegetable processing wastes are global challenges but also suitable sources with a variety of nutrients for different fermentative products using bacteria, yeast or fungi. The interaction of microorganisms with bioactive compounds in fruit waste can have inhibitory or enhancing effect on microbial growth. In this study, the antimicrobial effect of 10 bioactive compounds, including octanol, ellagic acid, (−)-epicatechin, quercetin, betanin, ascorbic acid, limonene, hexanal, car-3-ene, and myrcene in the range of 0–240 mg/L on filamentous fungi Aspergillus oryzae and Aspergillus niger were investigated. These fungi were both found to be resistant to all compounds except octanol, which can be used as a natural antifungal agent, specifically against A. oryzae and A. niger contamination. On the contrary, polyphenols (quercetin and ellagic acid), ascorbic acid, and hexanal enhanced A. niger biomass yield 28%, 7.8%, 16%, and 6%, respectively. Furthermore, 240 mg/L car-3-ene was found to increase A. oryzae biomass yield 8%, while a 9% decrease was observed at lower concentration, 24 mg/L. Similarly, up to 17% decrease of biomass yield was observed from betanin and myrcene. The resistant nature of the fungi against FPW bioactive compounds shows the potential of these fungi for further application in waste valorization.

The Influence of Hazelnut Skin Addition on Quality Properties and Antioxidant Activity of Functional Yogurt

There is an increasing interest in applying fruit-processing wastes as functional food ingredients. Hazelnut skin, an interesting and innovative ingredient has recently been evaluated as one of the richest edible sources of polyphenolic compounds. This study aimed to evaluate the use of hazelnut skin as a functional additive in yogurt and to determine the effect of various percentages (2%, 3%, and 4%) of hazelnut skin on the physicochemical, microbiological, rheological, biochemical, and sensorial properties of yogurt. The results showed that the addition of hazelnut skin significantly increased total solids from 16.5% to 17.7% and fat content from 3.45% to 4.60% and decreased titratable acidity by up to 36%. The enrichment with hazelnut skin also improved the viability of yogurt bacteria, water holding capacity (WHC), and antioxidant activity of yogurts. Better results for WHC and antioxidant values were found in yogurt enriched with 4% hazelnut skin. Total phenolic content and Fe2+ chelating activity of yogurts increased with the increasing hazelnut skin ratio. However, yogurts with hazelnut skin had low instrumental texture parameters and apparent viscosity values. On the other hand, acceptable sensorial properties similar to control yogurts increase the consumption potential of yogurts enriched with hazelnut skin.