The present study aimed to investigate whether different citrus peel powders (orange, mandarin, and lemon) could be incorporated into polylactic acid (PLA), for the preparation and characterization of biodegradable films made of this fruit waste. In particular, films were prepared by the solvent [...] Read more. (This article belongs to the Special Issue Trends in Sustainable Food Packaging and Coatings)

Due to spoilage microflora and browning, minimally processed fresh-cut fruits have a short shelf life, and over the years, studies have shown the potential of using edible coatings to extend the shelf life and improve the safety of fresh-cut fruits. Recently, there has been a rise in research on the incorporation of probiotics in edible coatings due to the bespoke health and biopreservation benefits they impart. Therefore, in this study, lactobacillus strains (Lactiplantibacillus plantarum 75 and Bifidobacterium longum) were incorporated into a xanthan edible coating to enhance color retention, sensory properties, antioxidant retention (ascorbic acid, carotenoids, total phenols), and antioxidant activity (FRAP antioxidant power, ABTS scavenger activity) of fresh-cut cantaloupes and honeydew cucumis melo L. melons during cold storage at 5 C and 85% RH for five days. The edible coating was prepared by mixing 0.5% xanthan gum, 1% glycerol, and 2% citric acid solution with L. plantarum 75 (LAB 75) and Bifidobacterium longum bacteria separately, and the final lab count for each strain was made to be 8.0 log CFU/mL. Stable probiotic coatings with ζ-potential of between −39.7 and −51.4 mV and a PdI of 1 were developed, and the incorporation of the probiotic bacteria into the coating was justified using FTIR analysis. The probiotic coatings showed a typical pseudoplastic behavior, in which the viscosity curves fall as the shear rate increases. Thermal stability analysis showed a continuous and multi-step weight reduction in this work, illustrating how the edible coating components interact. The survival of both Lactobacillus strains was recorded on day 5. Both freshly cut melons coated with xanthan and loaded with Lactobacillus strains retained a sufficient quantity of probiotics at the end of storage, while L. plantarum 75 (7 log CFU/g for cantaloupe and 8 log CFU/g for honeydew) retained the highest viability compared to B. longum (6 log CFU/g for cantaloupe and 7 log CFU/g for honeydew). In comparison to the coated and uncoated control samples, the inclusion of L. plantarum 75 in xanthan coatings significantly retained the color properties, pigments (total chlorophyll and carotenoids), ascorbic acid, total phenols, and antioxidant activity (FRAP, DPPH, and ABTS). The overall acceptability of fresh cuts of cantaloupe and honeydew melons coated with xanthan gum loaded with L. plantarum 75 was higher than that of other treatments. Thus, xanthan gum loaded with L. plantarum 75 coating is most suitable for reducing postharvest losses in fresh cuts of honeydew melons and cantaloupe, which will help preserve antioxidant and bioactive properties. The xanthan gum loaded with L. plantarum 75 coatings exhibited the highest preservation impact; therefore, it can be recommended for the fresh-cut industry.

This study investigated the effects of Lactiplantibacillus plantarum 75 (LAB 75) fermentation at 37 °C for 48 h on the pH, total soluble solids (TSS), colour, total titratable acidity (TTA), carotenoids, and bioactivities of cowpea leaf smoothies from three cultivars (VOP 1, VOP 3, and VOP 4). Fermentation reduced the pH from 6.57 to 5.05 after 48 h. The TTA increased with the fermentation period, whilst the TSS reduced. Fermentation of the smoothies resulted in the least colour changes (∆E) in VOP 1 after 48 h. Fermentation of cowpea smoothies (VOP 1, VOP 3, and VOP 4) improved the antioxidant capacity (FRAP, DPPH, and ABTS), which was attributed to the increase in total phenolic compounds and carotenoid constituents in all of the fermented cowpea smoothies. VOP 1 was further selected for analysis due to its high phenolic content and antioxidant activity. The VOP 1 smoothie fermented for 24 h showed the lowest reduction in TPC (11%) and had the highest antioxidant (FRAP, DPPH, and ABTS) activity. Ltp. plantarum 75 was viable and survived the harsh conditions of the gastrointestinal tract, and, hence, could be used as a probiotic. VOP 1 intestinal digesta showed significantly higher glucose uptake relative to the undigested and the gastric digesta, while the gastric phase had higher levels of α-amylase and α-glucosidase compared to the undigested samples.

Anthracnose disease is still a threat to avocado fruit quality, and the use of fungicide (Plochloraz®) for its control has generated safety concerns that necessitate the search for alternatives. Therefore, the efficiency of lactic acid bacteria (LAB) isolated from fresh fruits and vegetables as biocontrol agents against Colletotrichum gloeosporioides was investigated in this study. Weissella cibaria 21 (LAB 21), Leuconostoc pseudomesenteroides 56 (LAB 56), Weissella confusa 17 (LAB 17), Lactiplantibacillus plantarum 75 (LAB 75), and Lactiplantibacillus plantarum 171 (LAB 171) were evaluated in vitro as potential biocontrol agents to replace the Prochloraz® that is currently used in susceptible avocado (Persea americana Miller) Fuerte fruit. To confirm the biocontrol activity of the selected LAB strains, the antagonistic growth, spore germination, LAB recovery, nutrient competition, acid tolerance, and biofilm formation were assessed. In fruit treated with a LAB cell suspension, curatively inoculated with C. gloeosporioides, or naturally infected avocado cv Fuerte fruit, the epicatechin content and expression of defense-related genes (PAL, LOX, AVFADl 2–3, AVFAEL, and FLS) were compared with Prochloraz® and sterile water (control) treatments. With LAB 56, LAB 75, and LAB 21, significant inhibition of radial mycelial growth (MGI) (>90%) and spore germination (100%) was observed similar to those due to Prochloraz®. The MGI increased with a reduction in nutrient concentration. LAB strains reduced anthracnose disease incidence and severity compared with Prochloraz® and were the highest in LAB 21 and LAB 56. The LAB 21 and LAB 56 strains produced strong biofilms against C. gloeosporioides. In contrast to LAB 56, the control, and Prochloraz®, and LAB 21 had the highest epicatechin content (406 mg/g) and upregulated the PAL, AVFADl 2–3, AVFAEl, and FLS genes, thereby reducing the incidence of anthracnose in avocado fruit. As a result, LAB 21 suspensions can be used as an alternative to Prochloraz® in the control of anthracnose disease.

Traditionally, cowpea (Vigna unguiculata) leaves are consumed by the sub‐Saharan population. Carotenoids and phenolic compounds in cowpea leaves possess great antioxidant properties; however, their bioaccessibility is affected by digestion. This study investigated the influence of in vitro digestion on carotenoids, antioxidant and antidiabetic capacity of three cowpea cultivars (VOP1, VOP3 and VOP4). Among the cowpea cultivars, VOP1 showed the highest 9‐cis‐β‐carotene (21.13%) bioaccessibility, VOP3 showed the highest all‐trans β‐carotene (32.11%) and α‐carotene (21.75%) bioaccessibilities and VOP4 showed the highest lutein (17.70%) and zeaxanthin (32.03%) bioaccessibilities. The ferric‐reducing antioxidant power, 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging (DPPH) activities, 2,2′‐azino‐bis‐3‐ethylbenzthiazoline‐6‐sulphonic acid), α‐amylase and α‐glucosidase inhibitory effects decreased in the small intestinal phase. The cowpea cultivars demonstrated a high ability to meet the recommended daily allowance for carotenoids. As a result, the findings of this study show that cowpea leaves have the potential to be used as functional ingredients.