CO2处理对货架期‘磨盘柿’品质的影响研究

以‘磨盘柿’为试材,研究90%浓度的CO2气体处理10~12 h对‘磨盘柿’货架期间柿果果胶、硬度、可溶性固形物、Vc、可溶性单宁、可溶性滴定酸等指标变化的影响。结果表明,CO2处理可促进‘磨盘柿’果实货架期间果胶含量、硬度、Vc含量、单宁含量的降低,可溶性固形物、可滴定酸保持稳定;CO2处理后的‘磨盘柿’果实在21天的常温货架下能保持硬脆而且完成脱涩。     

Characteristics and thermodynamics analysis ofoxyacetylene flame brazing joint of Cu/Al tubes

以磨盘柿为试材,研究不同液浸处理对冰温贮藏(-0.5～-0.2)℃柿果涩味转变、品质及生理指标的影响。结果表明:在冰温条件下,用2%浓度的NaCl溶液贮藏磨盘柿,可使果实的乙醇含量在贮藏30～45 d内急剧增加,促进可溶性单宁的降低,在贮藏45 d时达到完全脱涩,并可有效延缓果实硬度的下降,具有脱涩和保脆的双重作用,同时可保持相对较高的可溶性固形物和可滴定酸含量,抑制贮藏后期果实丙二醛和膜相对电导率的增加,减缓果实的衰老进程。     

1-MCP处理对“丽格”海棠果实采后生理及品质的影响

以"丽格"海棠果实为试材,研究经1.0μL/L的1-MCP处理后,室温(20±1)℃条件下贮藏的海棠果实品质和生理变化,并利用主成分对采后测定的各项生理指标进行分析。结果表明,与不加1-MCP的对照组相比,1-MCP处理可保持海棠果实硬度,抑制可溶性固形物(TSS)含量的升高,减缓VC含量的降低、果皮叶绿素的分解和过氧化物酶(POD)活性的下降,降低呼吸强度和乙烯生成速率,有效地延缓果实衰老,使海棠果更耐贮藏。主成分分析在特征值大于1时将经1-MCP处理后的海棠果实8个生理指标综合为2个因子,累积方差贡献率达到84.44%,其中第1主成分主要代表果肉硬度和叶绿素信息,第2主成分主要代表乙烯释放量信息。     

气调贮藏对白玉枇杷保鲜效果的影响

对天津蓟县磨盘柿进行冷藏保鲜效果试验.结果表明,在(0±0.5)℃低温条件下,柿果贮藏30天时出现一个小的呼吸高峰值;在贮藏80天内,乙烯生成速率始终呈缓慢上升趋势,而硬度随时间推移呈线性下降.贮藏初期,柿果中可溶性单宁含量急剧下降,贮到66天时其含量已降到0.02%,低于果实的涩味阈值.维生素C含量在贮藏初期20天内明显上升达到高峰值,以后总趋势呈逐渐降低.试验同时发现,在20℃条件下磨盘柿具有典型的呼吸跃变现象.     

1-MCP对磨盘柿常温保脆效果的影响

以磨盘柿为试材,利用1-MCP与PVC自发气调保鲜袋综合处理技术,观察常温条件下磨盘柿果实货架保脆效果.结果表明,1-MCP处理有效地延缓了果实成熟与软化,可以明显地抑制柿果实硬度、可溶性固形物含量、VC含量、可溶性单宁含量及乙烯和呼吸强度的变化,但对可滴定酸含量变化影响不明显,试验同时发现,采用0.03mm厚PVC保鲜袋处理效果优于0.06mm厚PVC保鲜袋,采用0.50μL/L 1-MCP和0.03mm厚PVC自发气调保鲜袋综合处理技术取得了较为理想的保鲜效果.     

五种秋子梨果实采后品质变化及生理差异研究

以京白梨、南果梨、花盖梨、尖把梨、安梨5种秋子梨果实为试材,研究其在常温(20±1)℃下果实采后品质变化及生理差异,并分析了果实硬度与其他品质指标的关系。结果表明,供试品种货架期长短存在差异;在后熟过程中,五种秋子梨果实硬度和VC含量均呈下降趋势,可溶性固形物(SSC)含量和相对电导率均呈上升趋势,果皮色泽由绿转黄;京白梨的呼吸强度显著高于其他4种秋子梨(P0.05)且有呼吸跃变峰;京白梨、南果梨、花盖梨及尖把梨的乙烯释放速率均呈先升高后降低的趋势,且均存在乙烯释放跃变,京白梨和南果梨的乙烯释放速率极显著高于其他3种秋子梨(P0.01),安梨没有乙烯跃变峰且乙烯释放速率最低。硬度与其他品质指标的相关性分析表明,除了果实硬度、VC含量、果皮色泽和相对电导率影响秋子梨果实后熟软化外,京白梨的可滴定酸(TA)含量,南果梨的SSC和呼吸强度,以及安梨的SSC均与果实后熟软化呈显著(P0.05)或极显著相关(P0.01)。     

1-MCP对磨盘柿成熟软化的影响

采用不同浓度的1-MCP(1-甲基环丙烯)和不同处理温度对磨盘柿果实成熟软化的影响进行了研究.结果表明,适宜的1-MCP处理(浓度0.1～1 uL/L)可明显地延缓磨盘柿果实硬度下降,降低果实呼吸强度,推迟呼吸高峰的出现,并能显著地抑制果实乙烯释放,推迟其成熟软化,对延长磨盘柿贮藏期具有一定的作用.     

聚乙烯膜包装对磨盘柿贮藏品质的影响

以不同厚度(20、30、50μm)的聚乙烯(PE)保鲜膜和打孔聚乙烯膜(20μm)包装磨盘柿,以裸放柿子为对照,在(0±0.5)℃下对磨盘柿进行贮藏,通过测定柿果的VC含量、可溶性糖含量、丙二醛含量、果肉组织相对电导率和果肉硬度的变化和对外观品质的分析,研究自发气调包装对磨盘柿的保鲜效果。结果表明,自发气调包装可保持磨盘柿较高的VC和可溶性糖含量,显著抑制果肉丙二醛含量和果肉组织相对电导率的上升,减缓硬度下降速率,减少失水起皱和病斑的发生,抑制果肉、果皮色泽加深和褐变程度。自发气调包装对磨盘柿有显著的保鲜效果。50μm厚的聚乙烯保鲜膜包装袋内氧气含量为14%±1.1%,二氧化碳含量为5.5%±0.3%,袋内磨盘柿的VC含量、果肉硬度显著高于其他包装(P0.05),丙二醛含量显著低于其他包装(P0.05),果皮不起皱、无病斑、无褐变,但可溶性糖低于其他包装。因此,50μm厚的聚乙烯保鲜膜包装具有显著的自发气调保鲜效果。     

冷藏处理对磨盘柿保鲜效果的影响

对天津蓟县磨盘柿进行冷藏保鲜效果试验。结果表明,在（0±0．5）℃低温条件下,柿果贮藏30天时出现一个小的呼吸高峰值;在贮藏80天内,乙烯生成速率始终呈缓慢上升趋势,而硬度随时间推移呈线性下降。贮藏初期,柿果中可溶性单宁含量急剧下降,贮到66天时其含量已降到0．02％,低于果实的涩味阈值。维生素C含量在贮藏初期20天内明显上升达到高峰值,以后总趋势呈逐渐降低。试验同时发现,在20℃条件下磨盘柿具有典型的呼吸跃变现象。     

五种秋子梨果实采后品质Postharvest Quality and Physiological Characters of Five Pyrus ussuriensis Maxim Varieties 变化及生理差异研究

以京白梨、南果梨、花盖梨、尖把梨、安梨5种秋子梨果实为试材，研究其在常温（20±1）℃下果实采后品质变化及生理差异，并分析了果实硬度与其他品质指标的关系。结果表明，供试品种货架期长短存在差异；在后熟过程中，五种秋子梨果实硬度和VC含量均呈下降趋势，可溶性固形物（SSC）含量和相对电导率均呈上升趋势，果皮色泽由绿转黄；京白梨的呼吸强度显著高于其他4种秋子梨（P＜0.05）且有呼吸跃变峰；京白梨、南果梨、花盖梨及尖把梨的乙烯释放速率均呈先升高后降低的趋势，且均存在乙烯释放跃变，京白梨和南果梨的乙烯释放速率极显著高于其他3种秋子梨（P＜0.01），安梨没有乙烯跃变峰且乙烯释放速率最低。硬度与其他品质指标的相关性分析表明，除了果实硬度、VC含量、果皮色泽和相对电导率影响秋子梨果实后熟软化外，京白梨的可滴定酸（TA）含量，南果梨的SSC和呼吸强度，以及安梨的SSC均与果实后熟软化呈显著（P＜0.05）或极显著相关（P＜0.01）     

柿果脱涩技术

对柿果实脱涩机理的研究进行了概述,并讨论了乙醇与乙醛处理对涩柿果实脱涩的作用以及影响柿果实脱涩的因素.     

Postharvest physiology and browning of longkong (Aglaia dookkoo Griff.) fruit under ambient conditions

Longkong (Aglaia dookkoo Griff.) fruit rapidly loses its yellow skin color and turns brown after harvest. We aimed to elucidate the postharvest physiology and browning mechanism of longkong fruit stored at a 70–85% RH and at room temperature (25 °C). The respiration rate slightly decreased with progressive fruit browning, while ethylene production was dramatically increased. Preliminary experiments showed that ethylene treatment markedly increased peel browning, suggesting that this is induced by ethylene. The peel L-value continuously decreased during storage, in relation to the severity of peel browning. The peel surface morphological data indicated that the ultrastructure of longkong peel collapsed after harvest, especially around brown areas. The total phenolic content of peel tissue rapidly increased, concomitant with rapid increases in phenylalanine ammonia lyase (PAL) activity and browning score on day 2. Tissue from the lower part of the fruit had higher total phenolic contents, as well as polyphenol oxidase (PPO) and PAL activities, compared to the top and middle parts of the fruit; however, peroxidase (POD) activity slightly changed during storage, possibly independent of phenol oxidation. The browning of longkong peel was not associated with changes in soluble solids contents, titratable acidity or ascorbic acid levels.     

盘山磨盘柿贮藏保鲜技术研究

采用低温贮藏方法,配合乙烯吸收剂、吸氧剂、保鲜袋等新技术,在稳定条件下对柿子进行5个不同处理的保鲜试验,观察在贮藏期内呼吸强度、可溶性固形物、硬度、单宁等指标的变化情况,两年试验结果表明,处理1效果最好,贮藏120天后,基本保持了柿子的风味和品质,并保持较高的硬度.乙烯吸收剂、吸氧剂、保鲜袋和低温都有抑制呼吸,延缓衰老,延长保鲜期的作用.     

Changes in the microstructure and location of some bioactive compounds in persimmons treated by high hydrostatic pressure

Persimmon fruit are an important source of phenolic compounds, dietary fibre, and carotenoids. However, the location of these elements in the tissue is directly connected with processing techniques used. The aim of this work was to study the effect of high hydrostatic pressure (HHP) on the microstructure of persimmon fruit cv. ‘Rojo Brillante’ during different ripening stages and the relationship of this treatment with changes in the location of some bioactive compounds. Samples from persimmon fruit cv. ‘Rojo Brillante’ from two ripening stages, with and without deastringency treatment (95–98% CO₂), were treated by HHP at 200 and 400 MPa during 1, 3, and 6 min. A microstructural study using cryo-scanning electron microscopy, light microscopy, and confocal laser scanning microscopy (Cryo-SEM, LM, and CLSM) was carried out. Total soluble solid (TSS) content and some textural properties were also analyzed. The microstructural study showed that application of HHP caused cell wall disruption and intracellular component dispersion throughout the tissue, together with some nutritionally interesting compounds (tannins, fibres, and carotenoids). TSS content diminished in astringent samples when HHP was applied. This was attributed to precipitation of soluble tannins, which are responsible for fruit astringency. Therefore, it might be possible to omit a deastringency treatment with CO₂ before HHP treatments. HHP treatments caused an overall decrease in firmness for both ripening stages and an increase in cohesiveness (TPA analysis) in the more advanced stage.     

Deastringency treatment with CO2 induces oxidative stress in persimmon fruit

Because of astringency at harvest, ‘Rojo Brillante’ persimmons are regularly submitted to deastringency treatment based on exposing fruit to a high CO₂ concentration. The treatment conditions that ensure total astringency removal throughout the various maturity stages have been determined to be 95% CO₂, 20 °C, 24 h. The aim of this study was to investigate changes in the redox state of persimmon fruit associated with this deastringency treatment. The levels of reactive oxygen species (ROS) (O₂⁻ and H₂O₂), and the activities of the main ROS scavenging enzymes (CAT, POD, APX, and SOD), were determined at harvest and after deastringency in fruit at three different maturity stages.Our results showed that during ‘Rojo Brillante’ persimmon maturation, the level of O₂⁻ gradually increased, while APX activity was lowered. The deastringency treatment with CO₂ induced oxidative stress in the fruit, observed as an over-accumulation of O₂⁻ and H₂O₂. As a response to ROS accumulation, the activities of the CAT, APX and SOD scavenging enzymes were up-regulated after deastringency treatment. The response of POD enzyme was dependent on maturity stage, showing enhanced activity after CO₂ treatment only for the fruit at the most mature stage.     

1- MCP对冬枣常温贮藏生理和品质的影响

以白熟期冬枣为试材,经不同浓度1-MCP（250,500,1000nL/L）处理后,在常温条件下贮藏30天时,1-MCP处理能够显著抑制冬枣乙醇积累,保持较好的硬度、可溶性固形物和VC含量,降低腐烂指数和乙烯释放速率,提高贮藏后期呼吸速率,但对失水率和转红指数的影响不显著。不同浓度1-MCP处理以1000nL/L保鲜效果最佳。     

不同酵母发酵对柿子酒、柿子醋风味的影响

以盘山磨盘柿为试验材料,分别接种两种不同酵母菌发酵酿造柿子酒和柿子醋,通过顶空固相微萃取(HS-SPME)与气相色谱-质谱联用(GC-MS)技术研究不同酵母菌发酵对柿子酒、柿子醋香气成分的影响.结果表明:马克斯克鲁维酵母发酵的柿子酒与酿酒酵母发酵的柿子酒相比,香气物质的总含量增加了56.42％.其中,月桂酸乙酯、正癸酸、辛酸乙酯、乙酸苯乙酯、癸酸乙酯的含量提高明显,分别提高了177.91％、163.16％、137.36％、147.13％、110.37％.与酿酒酵母相比,马克斯克鲁维酵母发酵的柿子酒和柿子醋中均新增了一些高级醇、酯及酮类物质,由此可见,马克斯克鲁维酵母发酵可有效提高柿子酒、柿子醋中挥发性香气物质的种类和含量,起到提高柿子酒和柿子醋香气品质的作用.     

Does ethylene degreening affect internal quality of citrus fruit?

Citrus fruit are non-climacteric. However, exposure to exogenous ethylene, e.g., during ethylene degreening, stimulates various ripening-related processes in the peel tissue, such as destruction of the green chlorophyll pigments and accumulation of orange/yellow carotenoids. Nonetheless, it is not yet known whether exogenous ethylene affects internal ripening processes in citrus flesh. To address this question, we examined the possible effects of ethylene on taste, aroma, perceived flavor, and nutritional quality of various citrus fruit, including ‘Navel’ oranges, ‘Star Ruby’ grapefruit and ‘Satsuma’ mandarins. Exposure to ethylene enhanced peel color break, and respiration and ethylene production rates in all citrus fruit tested. However, ethylene degreening had no effect on juice total soluble solids and acid contents, and had only minor effects on contents and composition of juice aroma volatiles. Moreover, sensory analysis tests revealed that ethylene degreening did not affect the flavor of oranges and grapefruit, but marginally impaired sensory acceptability of mandarins; the latter change could be attributed, at least partially, to storage of the fruit for 5 days at 20 °C. Nevertheless, ethylene degreening did not enhance off-flavor perception or accumulation of off-flavor volatiles, nor had any effect on levels of health promoting compounds such as vitamin C, total phenols and flavonoids, or antioxidant-activity of citrus juice. We conclude that although ethylene affects peel color break, it is probably not involved in regulation of internal ripening processes in citrus fruit and, therefore, does not impair internal fruit quality.