The Effect of Hydrothermal Treatment on Metabolite Composition of Hass Avocados Stored in a Controlled Atmosphere.

Avocado cv. Hass consumption has expanded worldwide given its nutritional, sensory, and functional attributes. In this work, avocado fruit from two harvests was subjected to hydrothermal treatment (38 °C for 1 h) or left untreated (control) and then stored for 30 and 50 days in a controlled atmosphere (4 kPa O2 and 6 kPa CO2 at 7 °C) (HTCA and CA, respectively) with subsequent ripening at ~20 °C. The fruit was evaluated for primary and secondary metabolites at harvest, after storage, and after reaching edible ripeness. A decrease from harvest to edible ripeness in mannoheptulose and perseitol was observed while ß-sitosterol, hydrophilic and lipophilic antioxidant activity (H-AOX, L-AOX), abscisic acid, and total phenolics (composed of p-coumaric and caffeic acids such as aglycones or their derivatives) increased. HTCA fruit at edible ripeness displayed higher contents of mannoheptulose, perseitol, ß-sitosterol, L-AOX, caffeic acid, and p-coumaric acid derivatives, while CA fruit presented higher contents of α-tocopherol, H-AOX, and syringic acid glycoside for both harvests and storage times. The results indicate that a hydrothermal treatment prior to CA enables fruit of high nutritional value characterized by enhanced content of phenolic compounds at edible ripeness to reach distant markets.

Coatings with chitosan and phenolic-rich extract from acerola (Malpighia emarginata D.C.) or jabuticaba (Plinia jaboticaba (Vell.) Berg) processing by-product to control rot caused by Lasiodiplodia spp. in papaya (Carica papaya L.) fruit.

This study evaluated if coatings with chitosan (Chi) and phenolic-rich extract from acerola (Malpighia emarginata D.C., PEA) or jabuticaba (Plinia jaboticaba (Vell.) Berg, PEJ) processing by-products are effective to control the development of rot caused by Lasiodiplodia pseudotheobromae, L. viticola, L. euphorbicola, L. theobromae and L. hormozganensis in papaya (Carica papaya L.) fruit. Effects of formulated coatings on some physicochemical parameters indicative of postharvest quality of papaya were investigated. Twenty-six different phenolics were found in PEA and PEJ, including flavonoids, stilbenes, tannins and phenolic acids. Chi (1-5 mg/mL), PEA and PEJ (25-100 mg/mL) separately caused mycelial growth inhibition on all isolates. Combinations of Chi (3 and 4 mg/mL) and PEA (50 and 75 mg/mL) or PEJ (75 and 100 mg/mL) had additive interactions. Coatings with Chi (4 mg/mL) and PEA (50 or 75 mg/mL) or PEA (75 or 100 mg/mL) inhibited rot development in papaya fruit infected with Lasiodiplodia isolates during 8 days of room temperature storage. Coatings with 4 mg/mL Chi and 75 mg/mL PEA or 100 mg/mL PEJ were the most effective to control rot development. These coatings did not affect negatively physicochemical parameters indicative of postharvest quality of papaya fruit during storage. Coatings with combined Chi and PEA or PEJ could be novel strategies to control postharvest rot caused by Lasiodiplodia in papaya fruit.

Relative Tolerance of Three Morphotypes of the Anastrepha fraterculus Complex (Diptera: Tephritidae) to Cold Phytosanitary Treatment.

The Anastrepha fraterculus (Wiedemann) complex is currently comprised of at least eight morphotypes, including several that are likely to be described as new species. It is critical to evaluate whether the morphotypes differ in tolerance to phytosanitary treatments. Temperatures from 0 to 3°C are used as a phytosanitary treatment for some commodities exported from the region and at risk of infestation by the A. fraterculus complex. Description of A. fraterculus morphotypes as new species could result in the annulation of phytosanitary treatment schedules for the new species. This study compared the relative cold tolerance of five populations from three morphotypes of the A. fraterculus complex: Andean, Peruvian, and Brazilian-1. Both a laboratory and wild strain of the Brazilian-1 morphotype were studied. Differences in mortality of third instars of the five A. fraterculus populations reared on nectarines were observed only with short treatment durations at temperatures ranging from 1.38 ± 0.04°C to 1.51 ± 0.08°C (mean ± SEM). Estimated times to achieve the LT99.99682 (probit 9) showed that Brazilian-1 wild, Brazilian-1 laboratory, and Cusco population were the most cold tolerant, followed by Andean and Peruvian, the least cold tolerant morphotype (i.e., Brazilian-1 wild = Brazilian-1 laboratory = Cusco population > Andean > Peruvian). These findings suggest that the current cold treatment schedules of 15 d at ≤ 1.11°C and 17 d at ≤ 1.67°C can be applied as cold treatments to any potential new species that may arise from the A. fraterculus complex.

Postharvest application of pectic-oligosaccharides on quality attributes, activities of defense-related enzymes, and anthocyanin accumulation in strawberry.

BACKGROUND: The postharvest application of pectic-oligosaccharides (POS) as an elicitor to improve the postharvest shelf-life and nutritional quality by stimulating natural defense mechanisms in strawberries was studied. Strawberries (cv. Festival) were treated with POS (at 0, 2, 5, and 9 g L-1 ) and evaluated for firmness, weight loss, color, soluble solids, titratable acidity (TA), total phenolic and anthocyanin content, antioxidant capacity, decay, and some defense-related enzyme activity during storage at 2 ± 0.5 °C for 14 days. RESULTS: Treatment with POS significantly delayed (P < 0.05) strawberry decay, and reduced the water loss and softening of fruit during storage. Strawberries treated with POS showed a significant increase in total phenolic and anthocyanin content, and antioxidant capacity when compared with controls. Interestingly, POS induced higher activity of phenylalanine ammonia-lyase (PAL), chitinase, and ß-1,3-glucanase in strawberries. Compared to the control, the activity of enzymes was markedly increased in fruit treated with all tested POS concentrations, particularly chitinase, and ß-1,3-glucanase activities, but 5 and 9 g L-1 POS were the most effective treatments for maintaining the quality attributes and improving anthocyanin accumulation and antioxidant capacity of strawberries. CONCLUSION: These findings suggest that POS treatment could potentially be applied to maintain quality attributes, reduce decay, and further enrich the anthocyanin content and antioxidant capacity of strawberries during postharvest storage. The results also suggest that the positive effects of POS on strawberries could be associated with the rapid accumulation of chitinase and ß-1,3-glucanase activities, and the increase of PAL enzyme activity leading to the synthesis and accumulation of anthocyanins. © 2019 Society of Chemical Industry.

Physiological response, antioxidant enzyme activities and conservation of banana treated with ethanol vapor.

Ethanol can inhibit ethylene and retard decay of several fruit. However, the effect of ethanol on ethylene and oxidative stress has not yet been observed in bananas. In this work, the effect of ethanol (vapor phase) on physiology and conservation of the banana cv. 'Prata' was investigated. Initially, a group of bananas was analyzed during 8 h of exposure to ethanol, and then another group of bananas was exposed to ethanol for 4 h and then analyzed during 12 days of storage. Ethanol and ethylene concentrations, respiration rate, superoxide dismutase and catalase activities, physico-chemical characteristics and fruit decay were evaluated. Ethanol reduced ethylene production and respiration rate of the banana only when it reached 4 h of exposure, and this was associated with a maximum absorption of ethanol in the fruit peel. Ethanol increased superoxide dismutase and catalase activities from fruit peel only in the first 2 h of exposure to ethanol, i.e. ethanol did not generate significant oxidative stress. During storage, ethanol inhibited ethylene production and was also able to delay fruit decay, but it was not able to influence the respiration rate, conversion of sugars, and fresh weight loss of the fruits. This study showed that ethanol vapor has an inhibitory effect on ethylene metabolism, but it has no potential to control post-harvest ripening of the banana cv. 'Prata'. On the other hand, ethanol delays decay, and this extends fruit shelf life, which is commercially advantageous.

An Analysis of the Published Literature on the Effects of Edible Coatings Formed by Polysaccharides and Essential Oils on Postharvest Microbial Control and Overall Quality of Fruit.

Consumers have shown increased concern about the importance of adopting regular fresh fruit consumption. Because fresh fruit are highly susceptible to postharvest decay, several studies have focused on the development of alternative technologies to extend their market period. The application of polysaccharides in combination with essential oils (EOs) to formulate edible coatings has been considered an innovative strategy to reduce postharvest losses in fruit. However, available studies have used different methodological procedures related to the production and application of these coatings on fruit, which could be potential influential factors on the achievement of the desired effects in coated fruit. This review summarized the studies focusing on the application of edible coatings formed by polysaccharides and EOs to preserve fruit, in addition to examine and discuss possible factors affecting their functionalities. The approach given in this review envisages to contribute to research in edible coatings formed by polysaccharides and EOs and help to their optimized application as a postharvest treatment of fruit. Despite of the different methods selected for use in experimental assays, data of available literature demonstrate that coatings formed by polysaccharides (that is, chitosan-the only polysaccharide used as an antimicrobial, cassava starch, flaxseed gum, gum arabic, hydroxypropylmethylcellulose, locust bean gum, mesquite gum, pectin, pullulan, and sodium alginate) and different EOs (or their individual constituents) are effective to reduce postharvest losses in fruit and generally do not adversely affected their physicochemical and sensory characteristics during storage.

Synergistic mixtures of chitosan and Mentha piperita L. essential oil to inhibit Colletotrichum species and anthracnose development in mango cultivar Tommy Atkins.

This study assessed the efficacy of chitosan (CHI) and Mentha piperita L. essential oil (MPEO) alone or in combination to control the mycelial growth of five different Colletotrichum species, C. asianum, C. dianesei, C. fructicola, C. tropicale and C. karstii, identified as potential anthracnose-causing agents in mango (Mangifera indica L.). The efficacy of coatings of CHI and MPEO mixtures in controlling the development of anthracnose in mango cultivar Tommy Atkins was evaluated. CHI (2.5, 5, 7.5 and 10 mg/mL) and MPEO (0.3, 0.6, 1.25, 2.5 and 5 µL/mL) alone effectively inhibited mycelial growth of all tested Colletotrichum strains in synthetic media. Mixtures of CHI (5 or 7.5 mg/mL) and MPEO (0.3, 0.6 or 1.25 µL/mL) strongly inhibited mycelial growth and showed additive or synergistic inhibitory effects on the tested Colletotrichum strains based on the Abbott index. The application of coatings of CHI (5 or 7.5 mg/mL) and MPEO (0.6 or 1.25 µL/mL) mixtures that presented synergistic interactions decreased anthracnose lesion severity in mango artificially contaminated with either of the tested Colletotrichum strains over 15 days of storage at 25 °C. The anthracnose lesion severity in mango coated with the mixtures of CHI and MPEO was similar or lower than those observed in mango treated with the synthetic fungicides thiophanate-methyl (10 µg a.i./mL) and difenoconazole (0.5 µg a.i./mL). The application of coatings containing low doses of CHI and MPEO may be an effective alternative for controlling the postharvest development of anthracnose in mango cultivar Tommy Atkins.

Coatings comprising chitosan and Mentha piperita L. or Mentha × villosa Huds essential oils to prevent common postharvest mold infections and maintain the quality of cherry tomato fruit.

In this study, we evaluated the efficacy of coatings comprising shrimp chitosan (CHI) and Mentha piperita L. (MPEO) or Mentha × villosa Huds (MVEO) essential oils to control mold infections caused by Aspergillus niger, Botrytis cinerea, Penicillium expansum and Rhizopus stolonifer in cherry tomato fruits (Solanum lycopersicum L.) during storage at room temperature (25°C for 12 days) and low temperature (12°C for 24 days). The effects of the coatings on the physicochemical and sensory characteristics of cherry tomato fruits during storage were also assessed. The minimum inhibitory concentration (MIC) of CHI against all test fungi was 8 mg/mL, whereas the MIC for both MPEO and MVEO was 5 µL/mL. Combinations of CHI at 4 mg/mL and MPEO or MVEO at 2.5 or 1.25 µL/mL strongly inhibited the mycelial growth and spore germination of target fungi. The coatings comprising CHI and MPEO or CHI and MVEO at the different tested concentrations delayed the growth of decay-causing fungi in artificially contaminated tomato fruit during storage at either room temperature or low temperature. The assayed coatings preserved the quality of cherry tomato fruit during storage, in terms of physicochemical and sensory attributes. These results indicate that coatings comprising CHI and MPEO or CHI and MVEO represent promising postharvest treatments to prevent common postharvest mold infections in cherry tomato fruit during storage without affecting the quality of the fruit.

Efficacy of a coating composed of chitosan from Mucor circinelloides and carvacrol to control Aspergillus flavus and the quality of cherry tomato fruits.

Cherry tomato (Lycopersicon esculentum Mill) fruits are susceptible to contamination by Aspergillus flavus, which may cause the development of fruit rot and significant postharvest losses. Currently there are significant drawbacks for the use of synthetic fungicides to control pathogenic fungi in tomato fruits, and it has increased the interest in exploring new alternatives to control the occurrence of fungal infections in these fruits. This study evaluated the efficacy of chitosan (CHI) from Mucor circinelloides in combination with carvacrol (CAR) in inhibiting A. flavus in laboratory media and as a coating on cherry tomato fruits (25°C, 12 days and 12°C, 24 days). During a period of storage, the effect of coatings composed of CHI and CAR on autochthonous microflora, as well as on some quality characteristics of the fruits such as weight loss, color, firmness, soluble solids, and titratable acidity was evaluated. CHI and CAR displayed MIC valuesof 7.5 mg/mL and 10 µL/mL, respectively, against A. flavus. The combined application of CHI (7.5 or 3.75 mg/mL) and CAR (5 or 2.5 µL/mL) strongly inhibited the mycelial growth and spore germination of A. flavus. The coating composed of CHI (3.75 mg/mL) and CAR (2.5 or 1.25 µL/mL) inhibited the growth of A. flavus in artificially contaminated fruits, as well as the native fungal microflora of the fruits stored at room or low temperature. The application of the tested coatings preserved the quality of cherry tomato fruits as measured by some physicochemical attributes. From this, composite coatings containing CHI and CAR offer a promising alternative to control postharvest infection caused by A. flavus or native fungal microflora in fresh cherry tomato fruits without negatively affecting their quality over storage.