Physical and metabolic alterations in "Prata Anã" banana induced by mechanical damage at room temperature

Abstract

Bananas respond at the physical and physiological level to mechanical damage. Mechanical injuries cause alterations in color and flavor, tissue softening, faster ripening, increased weight loss, increased invasion of microorganisms, and higher enzyme activity in the affected area. The purpose of this study was to verify the physical and metabolic alterations in 'Prata Anã' bananas induced by mechanical stress at room temperature. The experiment was conducted in a completely randomized, split-plot in time design, consisting of one control and four mechanical injury types: cutting, abrasion, impact and compression, sampled over time. The percentage of accumulated and daily fresh weight loss, electrolyte leakage from the injured peel region, total soluble sugar and starch contents and enzyme activity of polyphenoloxidase and peroxidase were measured. The damage caused by cutting and abrasion resulted in the highest percentage of fresh weight loss. All types of mechanical damage increased electrolyte leakage during the evaluation period, in comparison with the control. The impact damage anticipated the ripening, besides affecting the conversion of starch into total soluble sugars in the pulp. By impact and abrasion injuries, the polyphenoloxidase and peroxidase activity in the peel was increased by up to 231% and 90%, and 618% and 956%, respectively, compared to the control. Key words: postharvest, musa spp., injuryAlterações físicas e metabólicas em banana 'Prata Anã' induzidas por dano mecânico mantidas sob temperatura ambiente RESUMO: Bananas apresentam respostas físicas e fisiológicas ao dano mecânico. As injúrias mecânicas causam alterações na cor e sabor, amaciamento dos tecidos, amadurecimento mais rápido, aumento na perda de peso, aumento no ataque e invasão de microorganismos e maior atividade enzimática na área afetada. Verificaramse alterações físicas e metabólicas induzidas por estresse mecânico em bananas 'Prata Anã' mantidas em temperatura ambiente. Foi utilizado o esquema em parcelas subdivididas no tempo, constituído de testemunha e quatro fontes de dano mecânico: corte, abrasão, impacto e compressão, com amostragens ao longo do tempo, no delineamento inteiramente casualizado. As porcentagens de perda de massa fresca acumulada e diária, o extravasamento de eletrólitos da região danificada da casca, os teores de açúcares solúveis totais e amido e a atividade das enzimas polifenoloxidase e peroxidase foram avaliadas. Os danos por corte e abrasão promoveram maior porcentagem de perda de massa fresca. Todos os tipos de dano mecânico aumentaram extravasamento de eletrólitos em relação à testemunha ao longo do período de avaliação. O dano por impacto antecipou o amadurecimento, além de prejudicar a conversão de amido em açúcares solúveis totais na polpa. As injúrias por impacto e abrasão aumentaram a atividade das enzimas polifenoloxidase e peroxidase na casca em até 231 e 90%, e 618 e 957%, respectivamente, em relação ao controle. Palavras-chave: pós-colheita, musa spp., injúria

Reactive Oxygen Species Activity and Antioxidant Properties of Fusarium Infected Bananas

“…Peroxidase enzymatic assay Peroxidase (POD) assay was carried out as described by Maia et al (2011). Phosphate buffer and 0.5% frozen guaiacol were incubated at 30°C until the temperature stabilized.…”

Influence of the use of acids and films in post-harvest lychee conservation

“…PPO and POD activity on pericarp were determined by methods adapted from Maia et al (2011). The enzyme extract was obtained using 1g of pericarp added with 5 ml of 0.2 M phosphate buffer (pH 6.0), cooled in an ice bath and triturated in a polytron grinder at 20,500 rpm for 40 s. The suspension was centrifuged at 10,000 g for 21 minutes at 4 °C.…”

Banana Peel Physiological Post-Harvest Disorders: A Review

“…Physiology: It seems that browning linked to bruising would be triggered by enzymatic reaction [35]. For a same variety, sensitivity varies according to the fruit maturity stage at harvest [36].…”

“…However, temperature and humidity affects remain controversial [41,42]. Mechanical damages also stimulate respiratory process and ethylene biosynthesis [43,35]. Damaging the peel decreases its resistance and provokes loss of cell and membrane integrity [34].…”

“…Thus, phenolic compounds stored in vacuolesenters into contact with enzyme [44]. This induces oxidation of phenolic compounds to quinones, which polymerize then to brown pigments [41,35,45].…”