Bioactive components and antioxidant capacity of Chinese bayberry (<Emphasis Type="Italic">Myrica rubra</Emphasis> Sieb. and Zucc.) fruit in relation to fruit maturity and postharvest storage

Total phenolics, flavonoids, anthocyanins, cyanidin-3-O-glucoside (Cy-3-glu) and antioxidant capacity of Chinese bayberry fruit (Myrica rubra Sieb. and Zucc.) differed among the four cultivars “Baizhong” (white), “Fenhong” (pink), “Wuzhong” (red) and “Biqi” (dark red). Antioxidant capacity determined by both the ferric reducing antioxidant power (FRAP) assay and 2,2-diphenyl-2-picrylhydrazyl (DPPH^.) radical scavenging capacity was significantly correlated with the antioxidant components in the fruit, and directly related to fruit color. Cy-3-glu accounted for at least 82, 38, and 12% of the total antioxidant capacity in “Biqi”, “Wuzhong” and “Fenhong” fruits, respectively. No detectable Cy-3-glu was found in “Baizhong” fruit. Greater fruit maturity was associated with higher levels of all the bioactive components and antioxidant capacity. Significant increases were also found during postharvest storage of “Biqi” fruit held at either 20 °C for 2 days or 0 °C for 5 days. However, these levels decreased during a 2-day shelf-life at 20 °C after 5 days at 0 °C. These results show that storage and shelf-life conditions are important if health-based bioactive components of bayberry fruit are to be maintained after harvest.     

Evaluation of quality attributes and the incidence of Fusarium sp. and Aspergillus sp. in different types of maize storage

Maize is a highly nutritious cereal used in food and feed. Since maize production is seasonal in Brazil and the supply of the food chain occurs throughout the year, this cereal must be stored and is susceptible to a loss of quality and the development of potentially toxigenic fungi such as Aspergillus sp. and Fusarium sp. Thus this study aimed to evaluate the quality of maize grains kept under different types of storage for 12 months. A 4 × 5 factorial experimental design was used, the factors being four types of storage (conventional polypropylene sacks, vertical metallic silos, airtight bags and cobs) and five time periods (0, 3, 6, 9 and 12 months), using two maize varieties (2B688RR, 30K73H) produced in the 2012-winter crop in the town of Dois Vizinhos, state of Parana in the south of Brazil. The parameters evaluated in the experiment during each time period were: contents of moisture, ash, protein and lipids, the percentage of healthy kernels and the incidence of Fusarium sp. and Aspergillus sp. These genera were detected, respectively, in 85% and 22% of the samples. In both hybrids, the interaction between storage types and times influenced the moisture, ash and lipid contents, and also the incidence of Fusarium sp. in the hybrid 30K73H, and the percentage of proteins and healthy kernels in the hybrid 2B688RR. The percentage of healthy kernels in hybrid 30K73H was influenced by both the factors, individually, and the protein content only by storage time. The incidence of Fusarium sp. in the hybrid 2B688RR was influenced by both factors, individually, while the incidence of Aspergillus sp. was not influenced by the factors analyzed for either of the hybrids. Although small differences were found between the four types of storage, the hermetic polyethylene bags were shown to be a good option to maintain the maize grain quality.     

Microwave Finish Drying of Osmotically Dehydrated Cranberries

Abstract

Combined microwave and hot-air drying characteristics was studied for the drying of cranberries that had been previously partially dehydrated by osmosis in a high fructose corn syrup (76°Brix). A 750 W 2450 MHz microwave oven was used to dry cranberry samples from 57% to 15% moisture content using three different power densities (0.75, 1.0, 1.25 W/g of initial cranberries) and two different power cycles (30 s On/30 s Off and 30 s On/60 s Off). All combinations of these variables were tested in triplicate. Quality of the cranberries was measured using a universal testing machine, chromameter, and with the use of a taste test panel. Drying times ranged from 2.2 to 5.0 h. Power times and power cycles affected the drying time and the quality of the dried cranberries. Lower power densities resulted in cranberries with higher quality. High power densities (125 W/g) resulted in the burning of some cranberries.     

Influence of Different Thermohygrometric Conditions on Changes in Instrumental Texture Properties and Phenolic Composition during Postharvest Withering of ‘Corvina’ Winegrapes (Vitis vinifera L.)

‘Corvina’ winegrapes were postharvest withered under three controlled thermohygrometric conditions. Sampling was done on different days of withering and the mechanical properties, technological ripeness parameters, phenolic composition, and anthocyanin profile were determined. Depending on the condition, skin break force and pedicel detachment force significantly decreased during the dehydration process with a maximum variation of ?0.258 and ?1.306 N, respectively. Instead, total flavonoids of skin and seeds, and proanthocyanidins and low-weight flavanols of seeds increased, with a maximum variation of +1,483, +733, +1,022, and +469 mg/kg, respectively. The skin hardness was confirmed to be an important parameter for the dehydration kinetics.     

Efficacy of killer yeasts in the biological control of Penicillium digitatum on Tarocco orange fruits (Citrus sinensis)

Killer Saccharomyces cerevisiae and Wickerhamomyces anomalus yeast strains were tested as biocontrol agents against Penicillium digitatum, one the most important causes of postharvest decay in orange fruits.     

Influence of processing on the generation of γ-aminobutyric acid in green coffee beans

A determination of the concentrations of free amino acids in differently processed green coffees indicated the nonprotein amino acid -aminobutyric acid (GABA), a well-known plant stress metabolite, to be present in raw coffee beans (Coffea arabica L.) in significantly varying amounts. The GABA content of unwashed Arabica beans (green coffee produced by the dry processing method) was always markedly higher than that of washed Arabicas (wet processing method) as well as that of untreated seeds. This result underlined the assumption that during postharvest treatment a significant metabolism occurs within coffee seeds. A putative relation between drought stress of the coffee seeds and postharvest treatment methods is discussed. The GABA content of green coffee beans may serve as a potent tool to characterize the type of postharvest treatment applied in coffee processing.     

Yeast biocontrol of fungal spoilage of pears stored at low temperature

To reduce the use of fungicides, biological control with yeasts has been proposed in postharvest pears. Most studies of antagonists selection have been carried out at room temperature. However, in regions like North Patagonia where fruits are stored at − 1/0 °C during 5-7 months the selection of potential antagonist agents must be carried out at low temperature. In this study, 75 yeast cultures were isolated from healthy pears from two Patagonian cold-storage packinghouses. Aureobasidium pullulans, Cryptococcus albidus, Cryptococcus difluens, Pichia membranifaciens, Pichia philogaea, Rhodotorula mucilaginosa and Saccharomyces cerevisiae yeast species were identified. Additionally, 13 indigenous isolates of Penicillium expansum and 10 isolates of Botrytis cinerea were obtained from diseased pears, characterized by aggressiveness and tested for sensitivity to postharvest fungicides. The yeasts were pre-selected for their ability to grow at low temperature. In a first biocontrol assay using the most aggressive and the most sensitive isolate of each pathogen, two epiphytic isolates of A. pullulans and R. mucilaginosa were the most promising isolates to be used as biocontrol agents. They reduced the decay incidence by P. expansum to 33% and the lesion diameter in 88% after 60 days of incubation in cold. Foreign commercial yeast used as a reference in assays, only reduced 30% of lesion diameter in the same conditions. Yeasts were not able to reduce the incidence of B. cinerea decay. The control activity of the best two yeasts was compared with the control caused by the fungicides in a second bioassay, obtaining higher levels of protection against P. expansum by the yeasts. These two regional yeasts isolates could be promising tools for the future development of commercial products for biological control.     

采后果实内部酶促褐变机制研究进展

果实内部褐变作为一种特殊生理病害,虽然仅发生在少数果实中,例如菠萝、梨以及槟榔等,但是由于这些果实占有较大市场,所以,引起了研究者的广泛重视。目前普遍认为其直接原因是酶促褐变的结果。因此,本文结合目前国内外研究进展,着重从酶促褐变发生的条件——酚类底物、多酚氧化酶、O2进入果实组织内部机制以及最终区域化的破坏导致三者接触几个方面的研究进行了较为全面的综述;并且就果实内部褐变发生的诱因进行了概述。以期为今后进一步研究提供一定参考依据。