International audience

To investigate the effect of relative humidity (RH) on chilling injury (CI), zucchini fruit were stored in cold rooms (4 ± 0.4 ℃) with different RHs (near-saturated RH [NSH] with 96–100% and normal RH with 72–76% served as control). Storage in NSH delayed weight loss and CI, maintained firmness and skin color. Higher antioxidant enzyme activities and greater scavenging capacities of free radicals were found in NSH-fruit than in the control fruit. The decrease of the unsaturated fatty acids was delayed in NSH-fruit due to lower activities of related membrane lipid degrading enzymes as compared to the control fruit. NSH-fruit also maintained higher activities of energy metabolism-associated enzymes than control fruit, leading to high levels of adenosine triphosphate (ATP). Taken together, we attributed the alleviation of CI by NSH storage to its enhancement of antioxidant capacities and its effect on maintaining higher energy status in zucchini fruit.

Background: Fruit peel is a part of red dragon fruit that weighed 30-35% of the fruit weight and has not been used optimally. Red dragon fruit peel contains fiber, vitamin, flavonoid, tannin, alkaloids and has the potential as an antibacterial. Red dragon fruit peel can be processed into yogurt. Objectives: This research examined the antibacterial potential of red dragon fruit peel yogurt against Bacillus subtilis in hypercholesterolemic Wistar rats. Materials and Methods: Materials tested in this study were negative control, positive control, and caecum of hypercholesterolemic Wistar. This study used chloramphenicol as the positive control (K+) and DMSO 10% as the negative control (K-). The K1; K2; K3 were orally administered with 1.8 mL; 2.7 mL; 3.6 mL of red dragon fruit peel yogurt, respectively. Red dragon fruit peel yogurt was administered daily for 28 days. Caecum was collected and tested for antibacterial activity using disk diffusion (Kirby Bauer). The Bacillus subtilis was obtained from the Microbiology Laboratory of Center for Food and Nutrition Studies Universitas Gadjah Mada. Results: The average inhibition zone in K-; K+; K1; K2; K3 were 0.00±0.00 mm; 11.5±1.41 mm; 11.5±0.96 mm; 10.13±0.66 mm; 10.38±1.12 mm, respectively. The experimental animal groups, which received 2.7 mL and 1.8 mL of red dragon fruit peel yogurts, showed a significant difference compared to the positive control group (p= 0.026 and p=0.021, respectively). When the dose was increased to 3.6 mL, it showed no statistical difference in results (p=1.000). Conclusions: Red dragon fruit peel yogurt has an antibacterial potential against Bacillus subtilis.

Pathogen-induced decay is one of the most common causes of fruit loss, resulting in substantial economic loss and posing a health risk to humans. As an ethylene action inhibitor, 1-methylcyclopropene (1-MCP) can significantly reduce fruit decay, but its effect on fruit pathogens remains unclear. Herein, the change in microbial community structure was analyzed using the high-throughput sequencing technology, and characteristics related to fruit quality were determined after 1-MCP (1.0 M l L–1) treatment in “Doyenne du Comiceis” pear fruit during storage at ambient temperature. Overall, 1-MCP was highly effective in reducing disease incidence and induced multiple changes of the fungal and bacterial microbiota. At day 15, the microbial diversity of fungi or bacteria was reduced significantly in the control fruit (non-treated with 1-MCP), which had the most severe decay incidence. For fungi, in addition to Alternaria being the most abundant in both 1-MCP treatment (59.89%) and control (40.18%), the abundances of Botryosphaeria (16.75%), Penicillium (8.81%), and Fusarium (6.47%) increased significantly with the extension of storage time. They became the primary pathogens to cause fruit decay in control, but they were markedly decreased in 1-MCP treatment, resulting in reduced disease incidence. For bacteria, the abundance of Gluconobacter (50.89%) increased dramatically at day 15 in the control fruit, showing that it also played a crucial role in fruit decay. In addition, Botryosphaeria, Fusarium fungi, and Massilia, Kineococcus bacteria were identified as biomarkers to distinguish 1-MCP treatment and control using Random Forest analysis. The redundancy analysis (RDA) result showed that the amount of Botryosphaeria, Penicillium, and Fusarium were positively correlated with disease incidence and respiration rate of pear fruits while negatively correlated with fruit firmness. This investigation is the first comprehensive analysis of the microbiome response to 1-MCP treatment in post-harvest pear fruit, and reveals the relationship between fruit decay and microbial composition in pear fruit.

Blueberry fruit are highly prone to deterioration, especially during storage. Calcium (Ca) can influence fruit quality of many fruit crops since it is an important mediating agent in the control of cell metabolism. Our aim was to determine if the application of foliar Ca sprays at different Ca rates (0, 400 or 800 g Ca ha⁻¹) and timings (early: fruit set, 8 and 16d after fruit set-dafs; or late: 16, 24 and 32 dafs) affect long-term postharvest quality and condition of highbush blueberry ‘Liberty’ (V. corymbosum) fruits. During the 2014/15 and 2015/16 seasons nine-year-old plants, located in Perquenco, Araucania Region, Chile (38º43’88” LS), were used in the trials. Fruits were harvested at > 90 percent full color and stored for 15, 30 and 45d at 0 °C + 1d at 18-20 °C. Fruit firmness and mass loss were the only quality attributes that registered significant interactions between Ca rates and spray timing, along with strong positive and negative correlations, respectively with fruit Ca concentrations. Firmer fruit (up to 10% higher than control) and lesser moisture loss (1% better than control) was obtained with early Ca foliar application treatments. Ca rates and spray timing had significant interactions and increased fruit Ca levels, total phenolic content, the proportion of sound fruits and reduced the percentage of dehydrated and decayed berries after storage. Fruit Ca concentration was lower in control and with late preharvest Ca sprays, which led to higher polygalacturonase activity during storage. Results evidence that early preharvest Ca sprays increase fruit quality and reduce deterioration in cold storage.

In this study, effects of foliar Zn sprays at different periods on yield, fruit quality attributes, bioactive compounds and micro-macro elements of ‘Granny Smith’ (Malus x domestica Borkh.) apples grafted on MM111 rootstocks were investigated. Experimental treatments were arranged as control (without Zn sprays), Zn-1 [Zn sprays 1 month after full bloom (when the fruit had a size of a walnut)], Zn-2 (Zn sprays 1 and 2 months after full bloom) and Zn-3 (Zn sprays 1, 2 and 3 months after full bloom). Experimental trees were sprayed with 0.2% Zn (ZnSO₄.7H₂O). Compared to control, Zn sprays increased yields. SSC values of Zn-2 and Zn-3 treatments were lower than the control and Zn-1 treatments. The total phenolics and total flavonoids of Zn-treated fruit were lower than the control fruit. The greatest vitamin C and antioxidant activity were obtained from Zn-2 and Zn-3 treatments, respectively. Zn-2 and Zn-3 treatments had greater zinc and phosphorus concentrations than the control treatments and Zn-sprayed fruit had greater nitrogen and potassium concentrations than the control fruit. It was concluded based on present findings that Zn treatments could be used as an effective tool to increase yield, antioxidant activity and mineral elements of ‘Granny Smith’ apples.

Freshly harvested mature-green 'Sensation' mangoes were dipped for 10 min in 2 mM salicylic acid (SA) and 0.2 mM melatonin (MT) alone or in combination and stored at 23+-1deg C and 60–70%RH. SA or MT delayed ripening measured as higher green peel color (lower a* values), firmness, titratable acidity (TA) and membrane stability index (MSI) and lower weight loss, total soluble solids (TSS), TSS/TA ratio and hydrolytic enzyme activities (polygalacturonase, xylanase and alpha-amylase) compared to that of untreated fruit. Total phenolic content (TPC) in peel of treated fruit increased with fluctuations during ripening and was higher than the control. In pulp, TPC decreased up to 6 days but increased thereafter, and was higher in treated fruit than the control. Total flavonoid content (TFC) in the peel decreased while that in the pulp increased with fluctuations during ripening and was higher in treated fruit than the control. Vitamin C content decreased during ripening and was not affected by the treatments. DPPH radical scavenging capacity (RSC) in peel decreased during ripening and was higher in treated fruit than the control. However, RSC in pulp increased during ripening and was not affected by treatments, except for SA plus MT treatment that gave higher RSC than the control after 6 and 10 days. Polyphenoloxidase (PPO) activity increased during ripening and was lower in treated fruit than the control. Peroxidase (POD) activity increased during ripening and was higher in treated fruit than the control. SA and MT combination treatment provided no additional positive effects on most parameters. It is concluded that postharvest dipping in 2 mM SA or 0.2 mM MT delayed ripening and improved quality of 'Sensation' mangoes via inhibiting hydrolytic enzymes and enhancing antioxidant system of fruit and are suggested as natural alternative to synthetic chemicals.