Effects of short‐term N2 treatment on quality and antioxidant ability of loquat fruit during cold storage

BACKGROUND: Loquat fruit is susceptible to microbial decay and quality deterioration during postharvest distribution. In this study, in a search for effective alternatives to methods currently used for quality maintenance, the effects of short‐term pre‐storage N₂ treatment on the quality and antioxidant ability of loquat fruit were investigated. RESULTS: Loquat fruits were exposed to 100% N₂ for 6 h at 20 °C and then stored at 5 °C for 35 days. Short‐term N₂ treatment significantly delayed the increase in fruit decay rate and decreases in total soluble solid and titratable acidity contents, thereby maintaining better eating quality and extending the storage life of fruits. It also markedly delayed increases in membrane permeability, malondialdehyde content and superoxide anion production rate. In addition, N₂‐treated fruits exhibited significantly higher superoxide dismutase and catalase activities and lower lipoxygenase activity than control fruits. CONCLUSION: Short‐term pre‐storage N₂ treatment effectively reduced fruit decay and maintained quality in loquat fruits during cold storage. The reduction in fruit decay and quality deterioration by the treatment was correlated with enhanced antioxidant ability and reduced lipid peroxidation. Copyright © 2009 Society of Chemical Industry     

Suppression of blood glucose level by a new fermented tea obtained by tea‐rolling processing of loquat (Eriobotrya japonica) and green tea leaves in disaccharide‐loaded Sprague‐Dawley rats

BACKGROUND: In the field of food science, much interest has been focused on the development of alternative medicinal foods with the ability to regulate excess blood glucose level (BGL) rise. The authors have successfully developed a new fermented tea product (LG tea) by co‐fermentation of loquat (Eriobotrya japonica) leaf and summer‐harvested green tea leaf. The objective of this study was to examine the acute suppression effect of LG tea on BGL rise in disaccharide‐loaded Sprague‐Dawley (SD) rats and to evaluate its possible usage as an antidiabetic functional food material. RESULTS: As a result of single oral administration of hot water extract of LG tea (50 mg kg^?1) to maltose‐loaded SD rats, BGL at 30 min was significantly decreased by 23.8% (P < 0.01) compared with the control. A corresponding reduction in serum insulin secretion was also observed. The ED₅₀ value of LG tea (50.7 mg kg^?1) was estimated to be about 16‐fold higher than that of the therapeutic drug acarbose (3.1 mg kg^?1). CONCLUSION: No significant change in BGL was observed when sucrose or glucose was administered, suggesting that the suppression effect of LG tea was achieved by maltase inhibition, not by sucrase inhibition or glucose transport inhibition at the intestinal membrane. Copyright © 2010 Society of Chemical Industry     

Identification of α‐glucosidase inhibitors from a new fermented tea obtained by tea‐rolling processing of loquat (Eriobotrya japonica) and green tea leaves

BACKGROUND: A new fermented tea produced by tea‐rolling processing of loquat (Eriobotrya japonica) leaf with green tea leaf (denoted as LG tea) showed a potent antihyperglycaemic effect in maltose‐loaded rats. The aim of this study, therefore, was to identify α‐glucosidase inhibitors in the antihyperglycaemic tea product. RESULTS: LG tea had a threefold higher maltase‐inhibitory activity (IC₅₀ 0.065 mg dried extract mL^?1) than either the constituent loquat leaf or green tea alone. In addition, LG tea favourably inhibited maltase action rather than sucrase action. As a result of bio‐guided high‐performance liquid chromatography separations of LG tea, theasinensin A, theasinensin B, strictinin and 1,6‐digalloylglucose were newly identified as maltase inhibitors with IC₅₀ values of 142, 225, 398 and 337 µmol L^?1 respectively, along with previously identified catechins and theaflavins. CONCLUSION: Judging from the magnitude of the α‐glucosidase‐inhibitory contribution of each isolated compound to the overall inhibition of LG tea, catechins were the main candidates responsible for α‐glucosidase or maltase inhibition in LG tea, followed by theaflavins, theasinensins, strictinin and 1,6‐digalloylglucose. Copyright © 2010 Society of Chemical Industry     

枇杷幼果总黄酮提取工艺优化及其抗氧化活性分析

目的采用响应面法优化枇杷幼果总黄酮提取工艺,并考察其抗氧化活性。方法以总黄酮含量作为评价指标,以料液比、乙醇浓度、提取温度、提取时间为考察因素,采用单因素实验与响应面分析相结合的方法,探索最佳提取工艺,并采用总抗氧化能力检测试剂盒(total antioxidant capacity assay kit,ABTS)、1,1-二苯基-2-三硝基苯肼(1-diphenyl-2-picrylhydrazyl,DPPH)和亚铁还原能力实验(fluorescence recovery after photobleaching,FRAP)法分析其抗氧化活性。结果枇杷幼果总黄酮的最佳提取工艺为:液料比为1:64(g:mL),乙醇浓度为49%,提取温度为65℃,提取时间为20 min。在此条件下,枇杷幼果总黄酮的实际得率为76.038 mg/g,与预测得率75.046 mg/g接近。提取的枇杷幼果总黄酮经AB-8大孔树脂纯化,其抗氧化活性明显高于维生素C(VC)。结论响应面法提取枇杷幼果总黄酮工艺可行,且提取物具有很好的抗氧化活性。     

枫香叶分离物抗氧化活性及对枇杷的贮藏保鲜效果

以枫香叶分离物（枫香叶依次经乙醇提取、乙酸乙酯萃取、大孔树脂层析、50%乙醇洗脱后所得产物）为实验材料,分别研究其还原力及对1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基、O2－·、·OH的清除能力和对枇杷的贮藏保鲜效果。用10、30、50 mg/100 mL的枫香叶分离物溶液对枇杷果实进行浸泡处理,6 ℃贮藏,每5 d测定一次枇杷果实的腐烂指数、硬度、可溶性固形物含量、可滴定酸含量、相对电导率、过氧化物酶（POD）活性、苯丙氨酸解氨酶（PAL）活性、木质素含量等果实的品质和生理指标。结果表明：枫香叶分离物具有较高的还原力和DPPH自由基、O2－·、·OH清除率;且枫香叶分离物处理可以有效控制枇杷果实腐烂指数、硬度、细胞膜渗透性及PAL活性和POD活性的升高,延缓可溶性固形物、可滴定酸含量的下降和木质素的积累,对于长期贮藏的枇杷果实具有较好的保鲜作用,其中以10 mg/100 mL枫香叶分离物的实用性较好。     

枇杷果实热水和甜菜碱复合处理保鲜条件优化

以“解放钟”枇杷果实为试材,采用响应面试验研究不同的热水处理温度（40、45、50 ℃）、时间（5、10、15 min）以及不同浓度甜菜碱（5、10、15 mmol/L）对1 ℃冷藏枇杷果实品质的影响。通过对枇杷果实果心褐变指数、出汁率和硬度的测定,建立这3 个响应值的二次多项模型,分析其拟合度,并进行验证分析,同时利用模型的响应面对影响枇杷果实品质的关键因素及其相互作用进行探讨。结果表明,甜菜碱结合热处理降低采后枇杷冷害的最优条件为：处理温度44.36 ℃、时间9.14 min、甜菜碱浓度10.65 mmol/L。验证实验结果表明,该复合处理组褐变指数、出汁率、硬度分别为23.66%、58.91%、2.66 N,能有效抑制枇杷果实冷害症状,保持较好品质,且处理效果优于单独处理。     

枇杷果汁加工的酶处理技术研究

通过不同的果胶酶对枇杷果浆的处理及其酶促反应的影响因子试验,结果表明:果胶酶处理枇杷果浆,可明显提高枇杷的出汁率及汁的透光率,利于果汁的澄清;尤以pectinex BE3-L的酶解处理效果最好,可使枇杷的出汁率提高16%、透光率提高40%以上。该酶理想的使用参数为:浓度160mg/L左右,温度35～40℃,作用时间4h。     

枇杷-梨复合果醋发酵工艺的研究

试验以贡梨和长虹枇杷为原料,进行枇杷-梨复合果醋的研制,并对其醋酸发酵阶段的工艺进行研究.通过单因素试验探究醋酸菌接种量、发酵时间、装液量、初始酒精度和发酵温度对果醋发酵的影响,在此基础上以果醋酸度值为响应值,对果醋醋酸发酵阶段进行响应面优化,最终得出复合果醋发酵的最优条件:发酵温度为32℃,接种量为7.3％,初始酒精...     

外源NO联合壳聚糖/纳米TiO2涂膜复合处理对枇杷保鲜效果的影响

目的研究外源NO联合壳聚糖/纳米TiO_2涂膜处理对采后枇杷品质的影响,以期获得协同增效的枇杷保鲜方式。方法以蒙自"大叶子"枇杷为实验材料,分别采用蒸馏水(对照)、硝普钠(SNP,外源NO供体)处理、壳聚糖/纳米TiO_2涂膜处理、外源NO联合壳聚糖/纳米TiO_2涂膜处理观察枇杷在(4±1)℃下贮藏75 d过程中的品质变化。结果适宜浓度的外源NO(cSNP为0.05 mmol/L)能有效减缓采后冷藏枇杷果实的木质化进程,减少冷害的发生;适宜浓度的壳聚糖/纳米TiO_2复合涂膜液(c_(纳米TiO_2)为0.5 g/L)能有效抑制枇杷表面微生物的增长,降低呼吸强度和腐烂率;复合处理(外源NO+壳聚糖/纳米TiO_2)更为有效地降低了枇杷果实储存期间的菌落总数,减少了贮藏过程中水分的散失,有效地减缓了木质化败坏进程,更有利于枇杷的保鲜。结论相比于单一的外源NO或壳聚糖/纳米TiO_2涂膜处理,外源NO联合壳聚糖/纳米TiO_2涂膜处理对枇杷的保鲜效果更好。     

中蜂枇杷蜜与意蜂枇杷蜜中的理化指标及抗氧化活性分析

目的分析中蜂枇杷蜜与意蜂枇杷蜜的理化指标及其抗氧化活性。方法以江苏中蜂枇杷蜜与意蜂枇杷蜜为研究对象,对其理化指标和总酚酸、总黄酮含量进行测定,采用DPPH·和ABTS~+自由基清除试验测定其抗氧化活性。结果中蜂枇杷蜜和意蜂枇杷蜜的理化指标均符合GH/T 18796—2012《蜂蜜》,中蜂枇杷蜜和意蜂枇杷蜜之间的水分、淀粉酶值、葡萄糖、果糖、蔗糖、麦芽糖、乳糖、灰分均存在差异性;中蜂枇杷蜜的总酚、总黄酮、清除DPPH·自由基能力和ABTS~+自由基能力均显著优于意蜂枇杷蜜;枇杷蜜中总黄酮与清除ABTS~+自由基能力均存在良好线性关系,枇杷蜜中总酚与清除DPPH·自由基能力和ABTS~+自由基能力均存在良好线性关系。结论通过对中蜂枇杷蜜与意蜂枇杷蜜的理化指标及其抗氧化活性的检测,为中蜂枇杷蜜与意蜂枇杷蜜鉴定与检测提供理论依据,为枇杷蜜产品的开发提供理论支撑。