Practical long-term storage of strawberries in refrigerated containers at ice temperature.

This study investigated the effect of storage temperature in the presence or absence of film packaging on the Benihoppe and Kirapika varieties of Japanese strawberries stored for 28 days at 0°C and 3°C. The study was conducted in a 20-foot reefer container for practicality. Storage at 0°C suppressed decay and reduction in sugars and organic acids more efficiently than that at 3°C. Softening of fruit hardness was also suppressed depending on the variety. The reduction in sugars and organic acids did not affect strawberry palatability. Along with low temperature, long-term storage of strawberries also requires the use of film packaging, which prevents drying. Without film packaging, storage at both 0°C and 3°C decreased fresh weight significantly, resulting in loss of commercial value. In contrast, storage in film packaging decreased weight reduction to <5%, even after 28 days cold storage.

Placental tissue of greenhouse muskmelon (Cucumis melo L.) contains more gamma-aminobutyric acid with antioxidant capacity than the fleshed pulp.

Our previous study revealed that gamma-aminobutyric acid (GABA) in Earl's muskmelon is more concentrated in the inner than the outer parts of the fruit. Here, the GABA and antioxidant capacity of the placental tissue of muskmelon, which is considered waste, were evaluated for possible use as a source of bioactive compounds. The concentrations of GABA and related substances in the placental tissue were significantly higher than in the fleshed pulp, whereas glutamic acid and sugar levels were significantly lower. The two sites showed no difference in GAD activity. Furthermore, the placental site showed high antioxidant capacities based on 2,2-diphenyl-1-picrylhydrazyl and oxygen radical absorbance capacity for hydrophilic compounds assays compared with the fleshed pulp, because of the higher levels of total phenolic and L-ascorbic acids. Therefore, the placental tissue of muskmelons may be useful for developing functional foods, which would also reduce the amount of residues during muskmelon processing.

Effects of distribution of sugars and organic acids on the taste of strawberries.

The concentrations of sugars and organic acids as well as the total soluble solid (TSS) in different parts of the strawberry fruit were characterized. The data were used to create simulated fruit juice jellies, in order to clarify how the sugar and organic acid levels affect the taste. Such an approach eliminates the influence of external factors such as size, color, and texture when using real fruits in sensory evaluations. Further, the use of a jelly allowed us to simulate the concentration differences between various parts of the fruit. In the strawberry fruit, the sugar content is higher in the apex than in the peduncle; however, the level of organic acids is the same throughout. It was revealed that the sweetness and sourness in the apex and peduncle could be sufficiently recognized by humans as tastes. Also, a layered jelly sample replicating the sugar and acid distribution in real strawberry was perceived as less sweet and more sour, compared to a homogeneous one with the same overall composition. The likely reason is that the sourness in the peduncle is accentuated by the low TSS level, which decreases the TSS/total organic acid ratio that affects the sweetness/sour perceptions. Based on these results, factors for the appropriate sensory evaluation of fresh fruits in general were considered. Specifically, the distribution of sugars and organic acids in the fruit should be analyzed first, and bite-sized parts with concentrations close to the average provide the most accurate evaluation results.

Differential GABA concentration gradients are present in the edible parts of greenhouse melon (Cucumis melo L.) during all four seasonal croppings.

Food-derived gamma-aminobutyric acid (GABA) exhibits health-promoting benefits, and melon contain high GABA concentrations. Greenhouse melons (Cucumis melo L. "Earl's Favorite") cultivated in Japan have identical or more edible parts than cultivars in other countries, however GABA distribution and the effects of seasonal variations are unclear. Thus, the present study aimed to evaluate GABA concentration gradients in four seasonal melons and how glutamic acid (Glu) influences the establishment of these gradients. GABA concentration was significantly lower near the exocarp than in the peduncle, equator, and remnant style regions in most seasons. Glu and GABA concentrations showed similar trends and were significantly correlated near the remnant style. No significant differences in GABA and Glu concentration were detected at concyclic sites across horizontal sections. These data indicate that GABA and Glu concentration differs substantially along a vertical melon section, but less so along a horizontal section, among sampling regions, sites, and cropping season.