Modifications of mechanical characteristics and phenolic composition in berry skins and seeds of Mondeuse winegrapes throughout the on‐vine drying process

BACKGROUND: Among several common drying systems used in the enological sector the dry‐on‐vine (DOV) method assumes particular importance because famous wines such as Sauternes, Tokay and Ice Wines are produced by grapes dried using this system. Knowledge about trends in mechanical properties and phenolic composition during on‐vine grape drying is scarce. The objective of this current study is therefore to increase the knowledge on these aspects. RESULTS: Berry skin break energy (+0.10 N) and berry skin thickness (+69 µm) values increase during grape dehydration, while the peduncle detach force decreases (?0.86 N). Large reductions in the anthocyanin content have also been observed (?40%), but their profile does not show significant changes. Seed hardness (?7.10 N, ?1.40 mJ) decreases during the withering, and higher seed springiness has been observed. Seed proanthocyanidins (+2050 mg kg berry^?1) and flavanols vanillin assay (+670 mg kg berry^?1) increase progressively throughout the withering. In contrast, a distinct lowering of these substances in the skins was noted. CONCLUSION: Many modifications in the chemical–physical characteristics of berries of Mondeuse winegrapes throughout the DOV process were found. The mechanical characteristics of grapes, in particular the peduncle detachment force, are important parameters in assessing their suitability for the drying‐on‐plant process. Copyright © 2009 Society of Chemical Industry     

Optimization of supercritical carbon dioxide extraction of sea buckthorn (Hippophaë thamnoides L.) oil using response surface methodology

Response surface methodology (RSM) was employed to optimize the conditions of supercritical CO₂ extraction of the whole berry oil from sea buckthorn. The effects of pressure, temperature, CO₂ flow rate and extraction time on the yield of oil, vitamin E and carotenoids were investigated. Results showed that the data were adequately fitted into three second-order polynomial models. The independent variables, the quadratics of pressure and extraction time, the interactions between pressure and temperature, pressure and extraction time, temperature and extraction time, as well as flow rate and extraction time had a significant effect on the yield of the oil, vitamin E or carotenoids. It was predicted that the optimum extraction conditions within the experimental ranges would be the extraction pressure of 27.6 MPa and temperature of 34.5 °C with flow rate of 17.0 L/h and extraction time of 82.0 min. Under such parameters, the yields of oil, vitamin E and carotenoids were predicted to be 208.0 g/kg, 288.7 mg/kg and 620.0 mg/kg dry sea buckthorn berry, respectively. Monounsaturated fatty acids were predominant in the whole berry oil, accounting for over 62% of the total fatty acids.     

‘霞多丽’葡萄果粒大小对果实品质的影响

酿酒葡萄果实品质和葡萄酒质量与果粒大小密切相关。本实验以云南香格里拉、宁夏玉泉营、山东烟台和新疆五家渠4 个产区的酿酒葡萄‘霞多丽’（Vitis vinifera L. cv. Chardonnay）为试材,按粒径分为大果粒（粒径大于14 mm）、中果粒（粒径14～12 mm）和小果粒（粒径小于12 mm）3 个等级,分别测定各粒径范围果实分布比例、果皮鲜质量、果实鲜质量以及果实可滴定酸、还原糖质量浓度和总酚含量等主要品质指标,并对果实品质进行主成分分析。结果表明：‘霞多丽’在4 个产区中果实多为中、小果粒,单果粒种子数及单粒种子质量均随粒径的增大而增加;可滴定酸质量浓度均在大果粒中较高;总酚和单宁含量除新疆五家渠葡萄表现为大果粒较高外,其他3 个产区均为小果粒较高;黄酮醇类总量在宁夏玉泉营葡萄中表现为小果粒较高,其他产区则为中果粒较高;黄烷醇类总量在云南香格里拉和新疆五家渠葡萄中表现为小果粒较高,宁夏玉泉营葡萄为中果粒较高,山东烟台葡萄则为大果粒较高。结论：主成分分析得出宁夏玉泉营的小果粒‘霞多丽’葡萄综合品质得分最高,新疆五家渠的大果粒‘霞多丽’葡萄综合品质得分最低;除山东烟台产区表现为大果粒‘霞多丽’葡萄得分较高外,其他3 个产区的‘霞多丽’葡萄综合品质得分都表现为小果粒＞中果粒＞大果粒。     

浆果果渣对酸奶品质和抗氧化性的影响

将1.50%的红树莓、蓝莓、黑加仑三种浆果果渣分别加入到酸奶中,研究三种浆果果渣酸奶在贮藏过程(4℃、21 d)中成分、品质和抗氧化能力的变化。浆果果渣总膳食纤维含量分别为45.24%、50.43%、55.21%,总多酚含量分别为18.40 mg/g、18.70mg/g、30.00 mg/g,总黄酮含量分别为3.00 mg/g、2.00 mg/g、2.90 mg/g,花色苷的含量分别为14.30 mg/g、14.10 mg/g、10.50 mg/g,DPPH自由基清除能力(提取液浓度10.00mg/mL)分别为92.20%、84.10%、61.00%。在贮藏期内,浆果果渣酸奶的乳清析出率和持水力随贮藏时间的变化趋势与对照样品相同,滴定酸度大于88.78°T,p H在4.17～4.51。浆果果渣的加入显著增加了酸奶的总膳食纤维含量,影响酸奶的硬度、黏度、凝聚力、粘性指数,提高了酸奶的抗氧化性,在贮藏期内最高可以达到对照酸奶的3.93倍(DPPH自由基清除能力)、13.11倍(总还原力)、4.28倍(羟自由基清除率)。浆果果渣可以作为功能性原料用于酸奶制品。     

青麦仁代餐粉的配方优化

为优化青麦仁复合代餐粉配方,采用单因素和均匀设计进行优化试验,并对结果进行多元回归分析。单因素试验结果表明:青麦仁粉添加量、青麦仁粉粒度、木糖醇添加量、羧甲基纤维素钠(CMC-Na)添加量、柠檬酸钠添加量对代餐粉冲调特性有较大影响。均匀设计及主成分分析结果表明:感官评分受柠檬酸钠添加量的影响程度大于青麦仁粉粒度;润湿性受各因素影响的主次顺序为CMC-Na添加量青麦仁粉粒度;溶解度、分散性、水合能力受各因素影响情况符合二次多项式回归模型;提取的4个主成分能解释92.72%的指标信息,达到指标降维目的;岭回归分析建立的综合得分回归模型具有较好的拟合度;偏最小二乘法回归分析预测最佳工艺参数为:青麦仁粉添加量61%,小米粉与燕麦粉添加量分别为18%、12%,青麦仁粉粒度125目,木糖醇添加量8%,CMC-Na添加量0.85%,柠檬酸钠添加量0.28%,实际综合得分为1.13,均高于试验组中的最高分。本研究参数为后续青麦仁代餐粉产品推广奠定基础。     

Rapid fingerprinting of grape volatile composition using secondary electrospray ionization orbitrap mass spectrometry: A preliminary study of grape ripening

We present a rapid and sensitive method based on secondary electrospray ionization mass spectrometry (SESI-MS) for profiling volatile emissions from the intact berries of non-Muscat grape cultivars (Pinot Noir, Chardonnay and Sauvignon Blanc). The method does not require sample preparation or concentration steps. Grape volatiles were tentatively identified based on accurate mass, the related elemental composition and literature. Approximately 300 peaks were detected in positive ion mode, and fewer (70–100) in negative ion mode. We monitored changes in grape berry volatile composition during ripening to screen for potential ripeness markers and observed ten [M+H]⁺ peaks and two [M-H]^- peaks that evolved in a significant linear trend (R² ≥ 0.80, p < 0.05) for the combined data across all cultivars either increasing or decreasing in the final four weeks of ripening. Peaks assigned to C₁₃-norisoprenoids and benzenoid derivatives have shown similar trends in previous studies using offline gas chromatography (GC) approaches. Principal components analysis showed that negative ion mode clearly separated each stage of grape ripeness, whilst positive ion mode only separated berries in the final stage, pre-harvest. From this preliminary study, we conclude that SESI-MS holds promise as a tool for rapid screening of grape volatiles. Some marker ions had no interfering peaks within a 1-Da window, such that they could be monitored with simple unit-resolution instruments in future studies. This implies that SESI-MS in combination with portable MS instrumentation has potential for field analysis where real-time analysis is key.