Causes of Decay of Fresh-cut Celery

A decay of fresh-cut celery (Apium graveolens) segments stored at < 5°C in sealed film bags began with a water soaking of the cut surfaces. Slimy moisture accumulated inside the bags. The segments water soaked completely, softened, discolored and sometimes disintegrated. Total aerobic bacterial populations isolated from decayed segments ranged from log₁₀ 7.0–7.7 CFU/g tissue weight. The predominant bacteria, identified by fatty acid analysis as Pseudomonas fluorescens and P. marginalis, caused water soaking, soft rot, and discoloration in freshly inoculated celery tissues stored at 5 or 25°C. Leuconostoc mesenteroides was also isolated and may have been responsible for slime production.     

Maintenance of postharvest quality and bioactive compounds of fresh‐cut sweet leaf bush (Sauropus androgynus L. Merr.) through hot CaCl2 dips

The effects of hot CaCl₂ dips on postharvest quality and bioactive compounds of fresh‐cut sweet leaf bush were investigated. The vegetable was dipped in 0.5% or 1.0% (w/v) of CaCl₂ solutions at 40 °C for 30 s and the control was the untreated sample. Hot CaCl₂ dips significantly delayed the weight loss, maintained the overall quality and inhibited the wiltness (P < 0.05). Both hot CaCl₂ dips had no effect on the changes in lightness (L*) and delayed the decrease in greenness (‐a*) and total chlorophyll content and the increase in both yellowness (b*) and carotenoid content. Hot CaCl₂ dips enhanced total antioxidants, total phenolics content and both AsA‐POD and G‐POD activities from 38.6, 0.44, 15.2 and 22.4 at day 0 to 55.3, 0.55, 50.5 and 362.4 at day 8, respectively. Moreover, hot CaCl₂ dips also delayed the loss of DPPH free radical scavenging activity, total flavonoid, ascorbic acid and CAT activity when compared to other treatments during storage. This study showed that hot CaCl₂ dip maintains postharvest quality and enhanced bioactive compounds of fresh‐cut sweet leaf bush during storage.     

采后果实链格孢属真菌病害防治方法研究进展

链格孢属真菌(Alternaria spp.)可引起多种果实采后发生病害,每年造成的损失异常严重,因此防治由链格孢属真菌引起的采后果实病害显得尤为迫切。文章将着重介绍国内外研究中采后果实链格孢属真菌病害的防治方法,包括采前防治,采后物理、化学和生物方法及联合防治等,并提出在未来的发展中应该使用新的、有效的组合方式来提高防治效果,增强果实抵抗链格孢属真菌的能力,延长果实采后贮藏期,提升其商品价值。     

Effects of hydrogen sulphide on quality and antioxidant capacity of mulberry fruit

Here we investigated the effect of hydrogen sulphide (H₂S) on postharvest quality of mulberry fruit and possible underlying mechanisms. Endogenous H₂S content first increased after harvest and then decreased sharply with the process of ripening and senescence. A fumigation with H₂S released from 0.8 mm NaHS solution could significantly enhance the endogenous H₂S content by increasing the activities of D‐cysteine desulfhydrase and L‐cysteine desulfhydrase. NaHS could significantly slow down the ripening rate of mulberry fruit and reduce the respiratory intensity and anthocyanin content. Moreover, H₂S fumigation was able to obviously delay or slow down the decreases in soluble protein, titratable acidity and ascorbate contents. Further results showed that activities of representative antioxidant enzymes in H₂S‐treated sample were higher than those of control samples during storage, resulting in a decrease in superoxide anion production. Together, these results clearly indicate that H₂S fumigation has a potential role in the preservation of mulberries.     

贵州水晶葡萄病原真菌分离鉴定及室内抑菌活性测试

[目的]确定引起贵州水晶葡萄采后贮藏病害的病原真菌种类及室内筛选用于该病害的主要防治杀菌剂。[方法]对病原菌进行分离纯化鉴定,通过科赫法则确定致病菌种类;筛选12种商品杀菌剂对炭疽病菌进行抑菌活性测定,筛选出有效药剂,为防治该病害提供一定的理论依据。[结果]从贵州省凯里市水晶葡萄采后贮藏病害分离鉴定出3株病原菌,为青霉菌(Penicillium sp.)、炭疽病菌(Clletotrichum gloeosporioides)和链格孢菌(Alternaria sp.),采用科赫法则,对3株病原真菌进行刺伤回接,发现3株均为水晶葡萄在贮藏过程中的主要致病菌。12种杀菌剂对水晶葡萄炭疽病菌进行室内抑菌活性测试结果表明:均具有较好的抑制活性,其中50%咯菌腈WP、50%苯菌灵WP、42%噻菌灵SC和43%戊唑醇SC对水晶葡萄炭疽病菌抑制活性最好,其EC50值分别为0.1024、0.1386、0.1624、0.1974 mg/L。[结论]凯里水晶葡萄采后病害病菌为青霉菌、炭疽病菌和链格孢菌;筛选出12种药剂针对水晶葡萄采后病害炭疽病菌的药剂,其中50%咯菌腈WP对炭疽病菌具有较好抑制效果,为水晶葡萄采后贮藏病害防治提供理论基础。     

Effect of pulsed ultrasound treatment compared to continuous mode on microbiological and quality of Mirabelle plum during postharvest storage

The effects of pulsed and continuous ultrasound treatment on microbiological and physiological quality of Mirabelle plum fruit were investigated. Freshly harvested Mirabelle plum was treated with 30‐kHz pulsed and continuous ultrasound at 20 °C for 0, 15, 30, 45 and 60 min and subsequently stored at 4 °C for 10 days. The total count of bacteria, total fungi, decay index, titratable acidity (TA), total soluble solids (TSS), colour, texture, ascorbic acid content and total phenolics was measured. The results showed that pulsed and continuous ultrasonic treatment significantly (P < 0.05) reduced the number of microorganisms and improved the quality of Mirabelle plums during storage. Increasing pretreatment time enhanced the positive effects of pulsed and continuous ultrasound. Also, in terms of the total count of bacteria, total fungi, titratable acidity and total phenolics, the pulsed and continuous ultrasound did not show a significant difference (P < 0.05). However, pulsed ultrasound was better compared to continuous mode in preservation of TSS, colour, texture and ascorbic acid content of the fruit during storage. Our results demonstrated that pulsed ultrasound is an appropriate method for improving safety and maintaining the quality of Mirabelle plum fruit.