This study addressed the effects of chitosan-based nanoparticles on microbiological quality, colour, polyphenol oxidase (PPO) and peroxidase (POD) and firmness of fresh-cut 'Gala' apple slices during storage at 5°C for 10 days. The treatments carried out were as follows: (i) slices pulverised with 110-nm chitosan nanoparticles, (ii) slices pulverised with 300-nm chitosan nanoparticles, (iii) 2 g L À1 chitosan dissolved in 2% citric acid and (iv) noncoated samples. There was an increase in chroma and a proportional decrease in hue angle and lightness. Browning of the slices coated with conventional chitosan and control was slightly intense than those coated with chitosan nanoparticles of 110 and 300 nm. The PPO and PDO activities increased with time for all samples, with irrelevant difference among the treatments. Flesh firmness did not change for any treatment and period. Coatings with chitosan nanoparticles of 110 nm showed higher antimicrobial activity against moulds and yeasts, and mesophilic and psychrotrophic bacteria than the other treatments. No Salmonella, and total and faecal coliforms were detected. This investigation supports the potential use of chitosan nanoparticles as edible coatings in controlling microbial activity in fresh-cut apples.

Umidade em cenouras, pimentões e salada mista minimamente processados, embalados sob ar atmosférico, vácuo e atmosfera modificada, armazenados sob refrigeração a 1ºC±1ºC .

No abstract

Production of purple-fleshed sweetpotatoes, source of anthocyanins, pigments with high antioxidant activities, is expected to be extended during the upcoming years, as there is a strong trend to market products promising improved health. This study aimed to evaluate yield, postharvest quality and pest resistance of roots of purple-fleshed sweetpotatoes. Six genotypes (BGBD 0005, BGBD 0080, BGBD 1261, BGBD 1399, BGBD 1402 and BGBD 1405) and the cultivars Beauregard and Brazlândia Roxa as controls were evaluated during two seasons 2018 (Experiment 1) and 2019 (Experiment 2), in Brasília-DF, Brazil. The experiments were conducted in a complete randomized blocks design with four replications, with experimental plots consisting of two rows of six plants. Roots were harvested about 140 days after planting and evaluated for yield, appearance, insect damage and quality characteristics as soluble solids, dry matter and color. All genotypes showed roots with good resistance to soil insects. The highest commercial production of genotypes BGBD 1261, BGBD 0005, and BGBD 1405 associated to quality traits (dry matter content and soluble solids) and pest resistance, showed their potential for being released as cultivars or to be used in breeding programs.

BACKGROUND: Cut flowers require proper postharvest stem hydration to prolong vase life. Nano-sized chitosan is an effective antimicrobial agent that has several potential agricultural applications. In this study, we compared the efficacies of solutions containing chitosan nanoparticles, regular chitosan particles, citric acid, and distilled and tap water controls in treating cut gerbera inflorescences during postharvest storage. Relative water uptake (RWU), transpiration rate (TR), water balance (WB), ligule color, solution pH, stem bending, stem-end blockage, and counts of bacteria, mold and yeast were investigated. RESULTS:The solution containing chitosan nanoparticles prevented stem bending, enabled higher RWU (41.8 g kg −1 day −1 ), established a suitable WB, and controlled microbial growth more efficiently than the other solutions. The chitosan nanoparticle solution strongly inhibited molds and yeasts. CONCLUSION:The results of this study demonstrated that nano-chitosan is a promising postharvest preservative for cut gerbera inflorescences.

No abstract

Fresh-cut apples were treated with an antibrowning solution and with a chitosan-based edible coating associated to antibrowning agents and the effects on the deterioration at low temperature were studied. The combined effect of ascorbic acid (AA), citric acid (CA) and chitosan was also evaluated. Control, coated and uncoated apples were packed in polyethylene terephthalate trays and the changes in headspace atmosphere, colour, firmness and microbial growth measured along ten days of storage at 5°C. The samples coated with 1% AA + 2% CA + chitosan maintained a good colouration until day 6, similar to those treated with 1% AA + 2% CA without chitosan. Afterwards, the fruits became darker and similar to the control. A slight reduction in the rates of CO 2 production was observed in all samples. Ethylene increased continuously during storage although gas production was extremely low. Texture did not change for all treatments; showing values around 9.0 to 10.0 N. Growth of Salmonella, and total and fecal coliforms were not detected. The chitosan coating treatment was the most effective in inhibiting growth of moulds and yeasts, with count of 1.7 CFU g-1. Chitosan coating could be an alternative for preserving quality of fresh-cut 'Gala' apples. Results from this study suggest that.

O presente trabalho teve como objetivo monitorar a qualidade físico-química e sensorial de abacaxi cv. ‘Smooth Cayenne’ minimamente processado e submetido à radiação gama. Os frutos foram descascados, fatiados em rodelas e sanificados com 20 mg.L-1 de cloro ativo. As fatias foram acondicionadas em bandejas de poliestireno recobertas com filme flexível de policloreto de vinila (PVC) e irradiadas com 1 e 2 kGy, sendo o controle não-irradiado. As amostras foram armazenadas a temperatura de 5±1ºC e avaliadas no primeiro, terceiro e sexto dias de armazenamento quanto à coloração, firmeza, sólidos solúveis (SS), acidez total titulável (ATT), pH e análise sensorial. O controle apresentou os menores valores de acidez e manutenção do pH em todas as avaliações, enquanto que o teor de sólidos solúveis foi maior na primeira avaliação para as doses de 1 e 2 kGy, decaindo com o decorrer do período de armazenamento. A irradiação não afetou a coloração dos abacaxis minimamente processados no período de avaliação, porém reduziu a firmeza das amostras na dose de 1 kGy. O controle apresentou as melhores notas nas avaliações sensoriais para os atributos aroma, sabor, textura e aparência. De maneira geral, os melhores resultados foram observados para o abacaxi minimamente processado não-irradiado (controle), sendo que as amostras irradiadas com 1 kGy obtiveram resultados inadequados para as análises de sólidos solúveis, acidez total titulável, pH, firmeza e sensorial.