Effects of wax coatings and postharvest storage on sensory quality and aroma volatile composition of ‘Mor’ mandarins

BACKGROUND: Mandarins suffer from accumulation of off‐flavours after harvest. In this study the sensory quality and aroma profile composition of homogenised segments of untreated (control) and wax‐coated ‘Mor’ mandarins after 7 days at 20 °C or 3 or 6 weeks of cold storage at 5 °C were examined. RESULTS: Fruit taste score decreased during storage and following wax coating, and this was attributed to decreases in sourness and mandarin flavour and accumulation of off‐flavours. Aroma profiling identified 31 volatiles that decreased by at least 50% during storage and after waxing and thus may be involved in the observed flavour loss. In contrast, 13 volatiles, mostly belonging to ethanol fermentation and fatty acid and amino acid catabolism pathways, significantly increased at least twofold and probably contributed to off‐flavour enhancement. CONCLUSION: The results showed that after harvest there was a progressive decrease in sensory quality of ‘Mor’ mandarins. It is proposed that observed decreases in contents of sesqui‐ and monoterpenes and short‐chain oxygenated fatty acids may contribute to the decrease in mandarin flavour, whereas increases in the contents of ethanol fermentation metabolites and derivates of fatty acid and amino acid catabolism are most likely involved in causing the enhanced sensation of off‐flavours. Copyright © 2010 Society of Chemical Industry     

贮藏温度对无核黄皮保鲜期和品质的影响

研究确定无核黄皮的最佳贮藏保鲜温度,为其贮运保鲜提供理论和技术基础。方法 无核黄皮经采收分拣后, 分别贮藏于不同的环境温度下,观测贮藏期间果实外观整体感观质量、色泽及主要生理和品质指标的变化。结果 较低温3~5 ℃、低温8~10 ℃下无核黄皮的总感官品质下降慢,贮藏保鲜期较长,分别达13 d和11 d,而中低温13~15 ℃下缩短至9 d,室温23~25 ℃则只有3 d。低温贮藏降低果实的呼吸和乙烯产生速率,减缓果面色泽劣变,并减缓可溶性固形物、可滴定酸和维生素C的变化,从而保持新鲜品质营养。结论 低温贮藏能有效减缓无核黄皮内外观品质的下降,温度越低,贮藏保鲜期越长。8~10 ℃是无核黄皮的最佳低温保鲜温度范围,此温度下的贮藏保鲜期为11 d。     

黄桃超声波辅助酶法去皮工艺优化及其品质分析

以金童5号黄桃为原料,采用超声波技术辅助酶法进行去皮,以感官评分为评价指标,经单因素试验和响应面试验优化,确定超声波辅助酶法去皮最优条件,并对最优工艺得到的黄桃与普通酶法去皮黄桃进行品质比较。结果表明:当超声波功率450 W、酶解温度45℃、酶解时间35 min、酶质量浓度0.31g/100 mL、酶液pH 3.5、黄桃与酶液料液比1∶3(g/mL)时,黄桃去皮效果最好,其感官评分最高。研究结果证明采用超声波辅助法,可以提高酶解效率和改善酶法去皮黄桃的品质:硬度提高40%,咀嚼指数提高121%,酶用量减少38%、酶解时间缩短12%。     

Effect of Intermittent Curing on Mandarin Quality

ABSTRACT: The effect of an intermittent curing treatment (IC), 2 cycles of 18 h at 38 °C, to control decay during shelf life of mandarins was studied. The effectiveness of IC to control blue mold development in artificially inoculated Clemenules fruits ( Citrus reticulata Blanco cv. Nules) was complete with 0% decay after 1 wk storage at 20 °C. Nonsignificant differences were found in soluble solids, color, and firmness. By the end of shelf life, a significantly lower acidity and a higher weight loss (4.75%) was observed in IC-treated fruits. Ascorbic acid levels decreased in all stored fruits along shelf life, with slightly lower values in IC-treated mandarins than in control fruits. Sugars and organic acids content were not affected by curing. Though slight increases in ethanol and some detrimental terpene oxidized compounds were found, not off-flavor development was observed. This, intermittent curing treatment seems to be a feasible treatment to control blue mold development during shelf life of Clemenules mandarin fruits, without impairing quality parameters such as color, firmness, sugars, and organic acids contents, vitamin C content, and aroma.     

Degradation of structural proteins and their relationship with the quality of Mandarin fish (Siniperca chuatsi) during post-mortem storage and cooking

This study was carried out to investigate the changes in the microstructure and structural proteins (titin, nebulin, desmin and tropomyosin (TPM)) of mandarin fish muscle as well as the relationship between the structural proteins and the quality characteristics of fish muscle during post-mortem storage and after cooking. During post-mortem storage, titin was degraded initially, accompanied with an increase of the I-band length. Subsequently, the degradation of desmin induced a gradual breakage of the myofibrils. The following degradation of nebulin accelerated the destruction of N₂-lines, which occurred with a slightly fuzzy Z-disc. Finally, TPM began to degrade, and the remaining desmin was also degraded further. Principal component analysis (PCA) and correlation analysis indicated that the changes in the quality characteristics of fish muscle were intimately related to the degradation of structural proteins. Hence, these structural proteins could be the biomarkers to monitor the quality characteristics of fish muscle.     

剥皮处理对黑小麦主要营养及加工品质的影响

通过剥皮处理,分析了剥皮程度对黑小麦主要营养品质和加工品质的影响。结果表明：与黑小麦面粉相比,剥皮处理可提高黑小麦全粉的营养品质,但相对降低其加工品质。随着剥皮程度增大,全粉中矿质元素的损失增大,VB1含量影响不大,全粉的蛋白质含量逐渐降低,降落数值升高,峰值黏度、破损值、回升值降低,拉伸参数也呈增大趋势;但两种黑小麦全粉的粉质参数表现出较大差异,其中杨凌黑小麦全粉的吸水率、形成时间、稳定时间及评价值均随剥皮程度的增加而增大,武功黑小麦全粉则呈相反变化趋势。因此,剥皮制粉可有效利用黑小麦的营养特性。     

外源L-Arg处理对蜜橘果实贮藏品质的影响

用100、200 μmol/L外源L-精氨酸（L-arginine,L-Arg）溶液浸泡处理蜜橘果实10 min,探讨该处理对采后蜜橘果实贮藏品质的影响。结果表明,适宜浓度（200 μmol/L）的外源L-Arg处理可以有效抑制蜜橘果实黄化,在一定程度上抑制果皮细胞膜透性的增加;在贮藏的前28 d内,L-Arg浸泡处理能够维持果实可溶性固形物的含量;各处理组之间的呼吸速率没有显著性差异,适宜浓度（200 μmol/L L-Arg）的L-Arg浸泡处理能够在一定程度上抑制蜜橘果实质量损失率的增加;延缓果实总酚、抗坏血酸含量的减少,贮藏前期（0～21 d）处理组果实果肉类黄酮含量与对照组之间无显著差异,贮藏后期（28～35 d）处理组果实类黄酮含量显著低于对照组果实。即200 μmol/L外源L-Arg处理能够在一定程度上有效延缓采后蜜橘果实的衰老和品质下降。     

大豆磷脂产品质量控制——大豆磷脂的颜色和风味

综述了大豆磷脂颜色的来源 ,大豆磷脂褐色物质的生成。介绍了磷脂中产生各种气味的物质和油脂加工过程中混合油吸附过滤和脱色、水化脱胶工艺条件、脱胶剂对大豆磷脂颜色的影响。对磷脂制备工艺中常采用的过氧化苯甲酰、过氧化氢化学脱色法以及浓缩磷脂的白土脱色、浓缩磷脂活性炭吸附脱色作了介绍     

Invited review: Modelling quality changes of fruits and vegetables during drying: a review

Fruits and vegetables have received much attention as these materials have been reported to contain various phytochemicals, which are claimed to exert many health benefits. When extraction of bioactive compounds cannot be performed on fresh fruits and vegetables, drying needs to be conducted to keep the materials for later use. Dried fruits and vegetables have also been regarded as alternative fat‐free snacks and received more attention from the food industry during the past decade. This implies that not only nutritional changes, but also other changes including physical and microstructural changes are of importance and need to be optimised, preferably through the use of various modelling approaches. The objective of this article is to provide a brief review of some advances in modelling quality changes of fruits and vegetables during drying. These include modelling of nutritional, colour and selected physical changes. Approaches to monitoring and modelling microstructural changes are also mentioned.     

无核蜜橘商品化处理适用果蜡筛选

以果蜡A、果蜡B、果蜡C和果蜡D 4种商品化果蜡,对北碚产无核蜜橘进行涂膜处理,通过测定不同果蜡处理对无核蜜橘贮藏品质的影响,探讨无核蜜橘果实商品化处理适宜的果蜡。结果表明:果蜡C及果蜡A能够有效降低贮藏蜜橘失重率,但果实腐烂率较高;果蜡D对果实转黄有一定的抑制效果,但果蒂褐变严重、果实腐烂率较高。果蜡B能有效地抑制果实转黄,延缓果蒂褐变,使果实保持较好的色泽,提高消费者接受度,还能有效地抑制贮藏前期蜜橘腐烂,保持贮藏期间蜜橘果实较高的可溶性固形物、可滴定酸和抗坏血酸含量。即果蜡B能够在一定程度上保持采后蜜橘的感官品质及营养价值,是北碚产无核蜜橘果实适宜的商品化果蜡。     

壳聚糖-纳米纤维素复合涂膜对砂糖橘贮藏保鲜效果的影响

为探究纳米纤维素（nanocrystal cellulose,NCC）的添加对壳聚糖涂膜保鲜效果的影响,本研究采用纯壳聚糖（chitosan,CS）涂膜液以及NCC质量分数为2%和4%的CS-NCC复合涂膜液（CS-2% NCC和CS-4% NCC）分别对砂糖橘进行涂膜,并以咪酰胺（prochloraz,PCZ）处理组和未处理组（CK组）为对照,测定各组果实在贮藏期间的质量损失率、腐烂率、营养品质指标、果皮中丙二醛含量以及抗氧化酶活力,并进行果皮表面微观形态的观察。结果表明,复合涂膜不能降低果实的质量损失率,但其对腐烂的抑制效果总体好于CS组和PCZ组;在贮藏24 d时,与CK组相比,CS-4% NCC组的腐烂率降低了50%;同时,涂膜可有效保持可滴定酸、可溶性固形物、总酚和可溶性蛋白等营养物质的含量;CS-4% NCC组果皮中的丙二醛含量最低,且该组在贮藏期间可维持较高的过氧化物酶与过氧化氢酶活力,说明CS-4% NCC复合涂膜可明显延缓果实的膜脂过氧化,从而使果实保持较好的抗衰老能力;从涂膜的微观形态可看出,果皮表面的涂膜在贮藏第1天便出现微孔,添加4%的NCC有助于减少微孔的出现,增强涂膜的结构稳定性。综上,添加NCC可改善CS涂膜的结构和性能,显著增强其对果实的保鲜效果。添加4% NCC的复合涂膜在抑制果实腐烂和保持果实品质方面与PCZ处理的效果接近,因此该复合涂膜有望替代化学保鲜剂在砂糖橘等柑橘果实的保鲜中进行应用。     

Pork quality from pigs fed on low glucosinate rapeseed meal: Influence of level in the diet,sex and ultimate pH

The appearance and eating quality of pork M. longissimus lumbrum from gilt and castrate pigs fed on diets containing a low glucosinate/low erucic acid rapeseed meal (cv. Tower) were assessed and compared with pork from pigs fed diets containing soya bean meal. At 90 kg liveweight, higher levels of either protein supplement, and therefore higher levels of dietary protein, gave slightly leaner meat. Meat from pigs fed rapeseed meal had more haem pigment and was slightly darker and redder than that from soya bean fed pigs. Differences in the quality of pork from the low glucosinate rapeseed meal and soya bean diets were small. Ratings for texture, juiciness and flavour of the lean varied little between the treatment groups. Suggestions that rapeseed meal as a protein supplement in diets might lead to inferior quality meat were not substantiated. The ultimate pH varied from 5.3 to 7.1 independently of the treatments and provided, for the first time, definitive relationships between pH and eating quality. Toughness and flavour were maximum and juiciness was a minimum after roasting meat of about pH 5.9. The ultimate pH had a larger effect on organoleptic quality than either sex or level of dietary inclusion of rapeseed or soya bean meals.     

谷氨酰胺转氨酶对鳜鱼鱼糜凝胶的品质影响

以鳜鱼鱼糜热诱导凝胶为研究对象,检测盐度、持水性、色泽、质构、感官评分、蛋白质二级结构、微观结构以及十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE)指标.研究谷氨酰胺转氨酶(transglutami...     

An Integrated Approach to Mandarin Processing: Food Safety and Nutritional Quality,Consumer Preference,and Nutrient Bioaccessibility

Mandarins are a member of the Citrus genus and are the focus of growing commercial interest, with satsuma mandarins (Citrus unshiu) and the common mandarin (Citrus reticulata Blanco) being the most important mandarin varieties. The possible health benefits and functional properties of those fruits are often associated with the antioxidative function of vitamin C, carotenoids, and phenolic compounds. While most mandarins are consumed fresh, many are processed into juices (mostly cloudy), usually via thermal processing which can lead to the creation of off‐flavors and may diminish nutritional quality. The aim of this review is to summarize the most significant and recent information on the safety, sensorial properties, and nutritional benefits of mandarins and their processing into juice. The article also discusses recent information regarding the bioaccessibility of valuable, mandarin specific, compounds.     

橘瓣酶解脱囊衣工艺及其罐头品质的研究

研究利用酶制剂脱除温州蜜柑橘瓣囊衣的方法。通过试验筛选最佳的酶及酶解工艺,结果表明使用和氏璧果胶酶,在酶液质量分数1.0%、pH 3.5、酶解温度45℃、酶解时间45 min条件下,可以得到较佳的脱囊衣效果;酶解过程中使用超声波辅助酶解,可以提高酶解效果。通过感官分析、理化指标检测,对比酶解脱囊衣和传统酸碱脱囊衣的橘瓣罐头的品质,结果显示酶解工艺提高橘瓣破碎率5.5%,降低维生素C含量20.4%,而不影响橘瓣的硬度、色差、滋味和气味。温州蜜柑橘瓣的酶解脱囊衣工艺可用于工业化生产橘瓣罐头。     

冷破碎工艺对猕猴桃果浆品质的影响

以海沃德、华优、红阳三个不同品种的猕猴桃为原料,利用冷破碎专利设备制取猕猴桃果浆。采用化学方法分析其营养特性指标(包括可滴定酸、总糖和还原糖、果胶、蛋白质、维生素C及多酚含量),同时与经传统工艺制取的果浆相比较,探讨冷破碎技术的优劣。实验结果表明,冷破碎工艺使海沃德、华优、红阳猕猴桃果浆酸度分别提高了69.9%、105%、34.2%,多酚及多酚氧化酶含量下降了49.4%、30.5%、43.8%和42.3%、48.3%、51.7%;总糖和还原糖变化不大,果胶、蛋白质含量变化显著。所以,采用冷破碎工艺获得的果浆比较好地保留了猕猴桃原果的营养品质,从防止营养品质劣变的角度看,冷破碎工艺是值得推广应用的果品加工先进技术。      

热风干燥温度对无核白葡萄干品质的影响

为了研究不同热风温度对葡萄品质的影响,以新疆吐鲁番无核白葡萄为材料,经促干剂处理后,分别在30,35,40,45℃条件下进行热风干燥。结果表明:在干燥无核白葡萄过程中,葡萄中的抗坏血酸、可滴定酸、总酚含量下降,而褐变度上升。综合比较可知,40℃热风干燥制得的葡萄干品质较好。     

Oenological tannins: a review

This review is a state‐of‐the‐art summary of current literature on the commercial oenological tannins that are often added to wine. These tannins can come from different origins, which affect their composition and characteristics. The two main sources of oenological tannins are grapes and oak wood. This review describes methods to quantify and characterise oenological tannins and indicates that these methods also need to be improved. These tannins have different interactions with proteins as well as with wine components such as anthocyanins and other phenolics in wine. The suppliers of commercial tannins often emphasise that these products can stabilise colour in red wine and influence the mouthfeel of the wine, among other things. The literature, however, suggests that the addition of these tannins often does not lead to large differences in the chemical profile of the wine and sometimes even leads to unwanted sensory characters being observed in the wine. More research clearly is needed regarding the role of oenological tannins in wine.