Search

W. Murcott (Citrus reticulata Blanco) is a variety of late-maturing mandarin in Chongqing of China that has been imported from the United States. There are more medium ripe citrus varieties, but fewer early or late ripe ones in the market. Late ripe W. Murcott can be held until March of the next year for better sustainable development of the citrus industry. In this study, the parameters were measured, including the color, sugar and acid components, ascorbic acid content, relative water content, firmness, weight loss rate, and rot rate of the fruits in seven harvesting periods during cold storage (0 - 150 days), thereby determining the effect of ripening on fruit quality and storability. Every 30 fruits were selected as a group, and three groups were taken in parallel for the determination of relevant indexes every 15 days. Graphpad Prism 5.0 software was selected to plot all recorded data. Analysis of variance (ANOVA) was performed on a SPSS17.0 software, and Duncan's multiple comparison was used to analyze the different significance. The results showed that the citrus fruits turned yellow completely in the VI harvest period at the time of harvest (day 0 of storage), where the ascorbic acid content, soluble solid content, and solid-acid ratio were the highest. The soluble solids content of fruits in the harvest period I was low, and the color changed slowly during the storage time. The fruits in the harvest period of V-VII were rotted during storage. In the harvest period of III and IV, the fruits did not deteriorate, where the weight loss rate was less than 5 %, and the ascorbic acid content was higher than that in other harvest periods at the end of storage. There were 8 kinds of soluble sugar and 9 kinds of organic acid in the fruit during the storage. The contents of fructose, sucrose, mannose, pyranose, ribose, and xylose all increased first and then decreased with the extension of the harvest period. The content of citric acid and aconite acid decreased with the delay of the harvesting period. The content of aconite acid in fruit was basically unchanged in the period of I-IV, and then decreased significantly during storage. It reached the lowest in the VI harvest period. The contents of malic acid, oxalic acid, propionic acid, fumaric acid, gluconic acid, α-ketoglutaric acid, and succinic acid in fruits all increased at first and then decreased with the delay of the harvesting period. In general, the harvest time needed to be adjusted to different commercial demands. The findings herein demonstrated that the fruit of harvest period VI (Feb. 7th) had complete color transformation while the soluble solid (11.60% ± 0.05%) and ascorbic acid content (21.15 mg/100g) were high, and the solid acid ratio (17.45) was optimal, suitable for fresh market. The decay rate of fruits in the harvest period III (Dec. 24th) was 0 after 150 days of storage. The highest content of ascorbic acid (15.27 mg/100g) and titratable acid (0.37%) was achieved at the end of low-temperature storage, with the high content of soluble solids (9.6%), while the firmness remained better (376 g), suitable for post-storage sales. [ABSTRACT FROM AUTHOR]

The production of traditional rose vinegar is an open, multilateral fermentation process, which is obtained through a series of reactions such as saccharification, alcohol fermentation and acetic acid fermentation. At the right time, rice supplement, sugar supplement or alcohol supplement can complete the fed-batch fermentation, among which alcohol supplement is closer to the end of the reaction which is the simplest way to achieve the expansion of production and efficiency. However, there has been no report on the improvement of the technique of fed-batch fermentation of rose vinegar production. Fermentation of rose vinegar with indica rice in 500 kg cylindrical fermentation container. Under the natural fermentation conditions, fed-batch fermentation was carried out at initial acidity of 1.5 g/100mL、2.5 g/100mL and 3.5 g/100mL, respectively. The ratio of vinegar to wine mash is set at 2:1 (v: v) and 1:1 (v: v). Through direct titration with Flynn reagent, alcohol distillation, indicator and potentiometric titration for acid-base titration, UV spectrophotometer, HPLC method, five important indexes including reducing sugar, alcohol content, acidity, color ratio and organic acid were determined. The effects of initial acidity and fed-batch volume on the fermentation of rose vinegar were studied. The results showed that the appropriate fed-batch volume could not only increase the yield of acetic acid fermentation, but also improve the acidity and efficiency of acetic acid fermentation. The color of rose vinegar depends on the feeding time and fed-batch volume. The earlier the vinegar is added, the closer the color is to traditional rose vinegar, but the more the vinegar is added, the greater the influence on the color is. Combining the change of organic acid composition and content with sensory evaluation results, the relationship between the improved fermentation mode and the formation of main flavor substances was discussed to determine the feasibility of fed-batch fermentation of rose vinegar. When the initial acidity was 2.5g/100mL, the maximum acidity increased to (5.59±0.27)g/100mL(control group (5.19±0.23)g/100mL) after adding the same amount of mash. Compared with the traditional rose vinegar, the acidity content increased significantly (P＜0.05). The time of acetic acid fermentation was shortened from 90 days to 78 days, which indicated that fed-batch fermentation could effectively improve fermentation efficiency and save more manpower, material and financial resources. The total amount of nonvolatile organic acids was (27.15±1.11) mg/mL (control group (24.57±0.69) mg/mL). The improvement of this index could make the samples have the characteristics of soft acidity and strong vinegar taste. The color ratio of the final product is 1.8×105 (the traditional process color rate is 1.9×105), which is consistent with that of the traditional rose vinegar. This study has positive significance for the production of rose vinegar to expand production, improve efficiency and realize continuous production throughout the year. [ABSTRACT FROM AUTHOR]