响应面法优化低脂甘薯脆片加工工艺

以红心甘薯为原料,优化低脂甘薯片生产过程中漂烫、热风干燥、油炸等关键工艺参数,以产品含油率和色差(L*值和b*值)为评价指标,并通过响应面优化确定最优的低脂甘薯片生产工艺.结果表明,较优漂烫工艺条件为:漂烫温度70℃,漂烫时间7 min;较优的热风干燥工艺条件为:热风干燥温度70℃,热风干燥时间40 min;最优油炸工...     

Acrylamide content in potato chips on the Italian market determined by liquid chromatography tandem mass spectrometry

An easy‐to‐use and simplified liquid chromatography‐tandem mass spectrometry (LC‐ESI (+)‐MS/MS) method was adopted to determine the amount of acrylamide in thirty‐two samples of potato chips purchased on the South Italian market in 2009. Extract produced from matrices was directly analysed without derivatisation, the use of isotopically labelled acrylamide or the use of clean up cartridges. Quality analytical data were reported. The limit of detection and limit of quantification were 6 μg kg^?1 and 18 μg kg^?1, respectively and recovery values ranged from 90.7–96.3%. The relative standard deviation (RSD) ranged between 2.1% and 5.8%. The values ranged between 27 and 1400 μg kg^?1 and the arithmetic mean acrylamide content resulted 363 μg kg^?1. According to Foot et al. [Food Additives and Contaminants, 24 (2007)(S1), 37] and considering 500 μg kg^?1 as the minimum level possible with the actual available mitigation tools, the number of samples showing an acrylamide level higher than 500 μg kg^?1 resulted to be 22%. This paper gives a contribution to data collection in response to the monitoring activity of EFSA and following the Commission Recommendation 2007/331/EC: really, the number of Italian samples of potato chips and potato products for which acrylamide values was reported in the ‘results on the monitoring of acrylamide’ of EFSA ( http://www.efsa.europa.eu/cs/BlobServer/Report/datex_report_acrylamide_en,0.pdf?ssbinary=true , 2009) issued on 30 April 2009 is very limited.     

葡萄糖氧化酶对油炸薯条中丙烯酰胺抑制作用研究

在单因素试验的基础上,采用响应面分析法研究了葡萄糖氧化酶的添加量、浸泡温度、浸泡时间对油炸薯条中丙烯酰胺形成的影响作用。结果表明:浸泡时间42min,浸泡温度70℃,葡萄糖氧化酶添加量1 700U/kg,丙烯酰胺最低生成量为240.62μg/kg。     

Survey on acrylamide in roasted coffee and barley and in potato crisps sold in Italy by a LC–MS/MS method

ABSTRACT

A survey on the occurrence of acrylamide (AA) in roasted coffee, barley, and potato crisps was carried out using an intra-lab validated liquid chromatography (LC)–MS (mass spectrometry)/MS method. Over the years 2015–2016, 66 samples of coffee, 22 of roasted barley, and 22 of potato crisps were collected from retail outlets in Italy. AA was detected in almost all samples. In roasted coffee, the level exceeded 450 µg kg^?1, the limit recommended by the European Commission (EC), in 36.4% of the samples. In roasted barley, mean contamination was slightly lower than in coffee and no sample exceeded the EC limit of 2000 µg kg^?1. The AA contamination in potato crisps was remarkable. A percentage of 36.4 (n = 8) showed a value higher than the EC limit of 1000 µg kg^?1. Considering the average consumption of coffee and potato crisps by Italian people, AA exposure is significant and should be decreased.     

Inhibition of acrylamide formation by vitamins in model reactions and fried potato strips

The capacities of 15 vitamins in reducing the formation of acrylamide were examined. Inhibitory activities of the water-soluble vitamins were tested in both chemical models containing acrylamide precursors (asparagines and glucose) and a food model system (fried snack products), while activities of fat-soluble vitamins were examined only in the latter model. Biotin, pyridoxine, pyridoxamine, and l-ascorbic acid exerted a potent inhibitory effect (>50%) on acrylamide formation in the chemical model system. Using the food model, it was shown that water-soluble vitamins are good inhibitors of acrylamide formation. On the other hand, only weak inhibitory effects were observed with fat-soluble vitamins. Effects of pyridoxal, nicotinic acid, and l-ascorbic acid were further examined using fried potato strips. Nicotinic acid and pyridoxal inhibited acrylamide formation in fried potato strips by 51% and 34%, respectively. Thus, certain vitamins at reasonable concentrations can inhibit the formation of acrylamide.     

Impact of chemical pre-treatments on the acrylamide formation and sensorial quality of potato crisps

Several components were added to the blanching water of potato crisps. Calcium ions, sodium acid pyrophosphate, citric, acetic and l-lactic acid significantly reduced the final acrylamide content, as well as free glycine and l-lysine. The acids, NaCl and calcium-containing additives also lowered the oil absorption, which may have led to a reduced heat transfer and acrylamide contamination in the final product. Textural and compositional product changes may thus also influence acrylamide formation. By means of sensory analyses of these crisps, a successful combination was demonstrated between acrylamide mitigating treatments and crisps of acceptable or even superior product quality, compared to control crisps blanched in water. However, the applied components and concentration levels should be well chosen in order not to generate product-foreign flavours or undesired product colour.     

Crisp quality of two potato varieties: Effects of dehydration and rehydration

Crisps adversely made from stored whole potatoes turn brown, whereas texture is adversely affected when crisps are made from dehydrated slices. Rehydration as a step prior to crisp-making has been investigated in two commercially grown potato varieties in Mauritius. The raw material was analysed for physical, chemical and processing characteristics including peeling losses, blanching time, drying rates and yield. Rehydration rates and ratios were determined. The sensory characteristics of the crisps were evaluated. Potatoes of the Exodus variety were smaller with more eyes and had higher peeling loss than those of the Spunta variety. The former had higher specific gravity and better drying characteristics. There were no significant differences between the varieties in respect of blanching time, chemical composition and crisp quality, and the drying curves were similar. Slight differences were observed in the rehydration characteristics. Crisps made from dehydrated slices were inferior in texture and taste to those of the control. However, crisps made from rehydrated slices were comparable to control crisps.     

Effect of pre-fry drying of oil uptake and distribution in potato crisp manufacture

Microwave, hot air (40 and 105°C) and freeze drying were used to remove varying amounts of moisture from 1.3 mm thick potato slices. The partially dried slices were then fried in oil at 165°C either for a constant 2 min or a variable frying time based on the amount of pre-drying. The microwave and hot air treatments resulted in a reduction in the final oil content, which was related to the degree of pre-fry drying. Freeze drying resulted in an increase in the oil content, again related to the initial moisture reduction. Oil distribution at the microscopic and macroscopic level was determined and found to be related to the initial moisture distribution in the slice. It is suggested that pre-fry drying may be a more successful point of influence than post-fry treatment in the manufacture of a'lower fat crisp'.     

半胱氨酸对马铃薯多酚氧化酶的抑制作用

马铃薯在保藏和加工过程中容易发生褐变,是因为其多酚氧化酶的作用结果。实验发现L-半胱氨酸对该酶有明显的抑制作用,它的作用可以导致马铃薯多酚氧化酶的酶促反应的迟滞时间延长,同时使稳态酶活力下降。其导致酶活力下降50%的抑制剂浓度(IC50)为100μmol/L。L-Cys对马铃薯多酚氧化酶的效应为不可逆的抑制,它作用于马铃薯多酚氧化酶活性而抑制褐色产物的产生,起到对马铃薯的保鲜作用。     

迷迭香酸的生理活性功能及其来源研究进展

迷迭香酸主要存在于唇形科(Lamiaveae),紫草科(Boraglnaceae)和伞形科(Apiacea)植物中,是1种具有抗氧化、抗菌、抗炎、抗过敏、抗血小板凝聚和抗血栓等功能的天然酚酸类化合物。文中介绍了近年来对迷迭香酸的生理活性功能和作用机制,及其主要获取来源的研究进展,并展望了其在食品工业中的应用。     

酶辅助超声提取紫苏迷迭香酸工艺优化及其抗氧化活性研究

通过单因素试验研究超声波功率、料液比、超声时间对紫苏迷迭香酸提取量的影响,采用响应面分析法和Box-Behnken试验设计优化酶法辅助超声波提取迷迭香酸的最佳工艺参数,并通过迷迭香酸对抗猪油氧化能力和清除羟自由基的能力来研究其抗氧化活性。结果表明,迷迭香酸最佳提取工艺为纤维素酶添加量3%、超声功率320 W、超声时间10 min、料液比1∶40（g∶mL）。在此最佳条件下,迷迭香酸提取量为1.426 mg/g。迷迭香酸对羟自由基有较强的清除能力,并能有效抑制猪油氧化。     

荞麦源降血糖糖肽结构表征及酶抑制动力学

为实现荞麦蛋白资源高值化利用,从6个菌株中筛选出植物乳杆菌和嗜热链球菌作为发酵菌株,制备α-葡萄糖苷酶抑制糖肽(α-GIG)。采用单因素实验确定优化中心点,然后做响应面试验优化发酵工艺。通过Sephadex G-25和反向高效液相色谱法(RP-HPLC)对发酵液进行分离纯化,制备α-GIG。采用β-消除反应方法确定α-GIG中糖肽键类型,红外光谱扫描法测定二级结构。采用Lineweaver-Burk作图法探究酶抑制动力学,确定α-GIG对α-葡萄糖苷酶的抑制作用类型。结果表明:在料液比1∶14.8、pH 7.5、接种量2%、发酵2.8 d条件下,发酵产物对α-葡萄糖苷酶抑制率达70.83%。发酵液经Sephadex G-25分离得到I1,I2,I3 3个组分,其中I2对α-葡萄糖苷酶抑制作用较强,IC50达1.72 mg/mL。经RP-HPLC进一步分离纯化I2,得到α-GIG,其纯度为94.17%。红外光谱扫描确定α-GIG的二级结构为:β-折叠占70.51%,α-螺旋占18.95%,β-转角占10.54%。α-GIG中糖肽键类型为O-糖肽键。酶抑制动力学研究表明,α-GIG对α-葡萄糖苷酶的抑制作用类型为混合型非竞争性抑制。α-GIG具有开发为天然α-葡萄糖苷酶抑制剂的潜力。     

响应面法优化重组型香梨脆片加工工艺的研究

以库尔勒香梨为主要原料,玉米淀粉和马铃薯淀粉为辅助原料,采用微波膨化工艺,通过响应面试验,确定了微波技术加工重组型香梨脆片的最佳工艺及相关参数,即香梨打浆后,添加21%生淀粉(其中玉米淀粉与马铃薯淀粉的比例为2︰1),经糊化、老化及90℃热风干燥后,在微波功率600 W下膨化95 s,此时得到的重组型香梨脆片产品成型性好,口感酥脆,有淡淡香梨味,色泽金黄,感官评分达87分。     

天然香料植物迷迭香研究进展

目的：采用低共熔溶剂（Deep Eutectic Solvents,DESs）同时提取迷迭香中的迷迭香酸（Rosmarinic acid,RA）和鼠尾草酸（Carnosic acid,CA）,并对提取工艺进行优化,为迷迭香抗氧化成分的有效开发利用提供参考。方法：首先制备37种不同组分的DESs,从中筛选出提取RA和CA得率最高的DESs组合;然后通过单因素实验研究不同的摩尔比、含水量（%）、液固比（mL/g）、提取时间（min）和提取温度（℃）对RA和CA得率的影响,在此基础上采用响应面法对提取工艺进行优化及验证,最后比较了DESs和传统溶剂（80%乙醇、正己烷）提取RA和CA的得率以及对DPPH·清除能力的差异。结果：乳酸/1, 4-丁二醇（摩尔比1:2）的DESs是同时提取RA和CA的DESs的最佳溶剂,优化的提取条件为：含水量12%、液固比44:1 mL/g、提取时间60 min,提取温度40 ℃。在该条件下RA和CA的得率分别为20.247和34.086 mg/g,相较于传统溶剂提取,DESs提取RA和CA的总得率分别提高了1.4倍（乙醇）和1.5倍（正己烷）,且耗时更短。以维生素C清除DPPH·的能力（浓度为0.03 mg/mL,清除率89.77%）为对照,相同浓度迷迭香药材（0.625 mg/mL）下,DESs提取物清除率为73.17%,优于乙醇提取物（66.93%）和正己烷提取物（62.57 %）。结论：DESs能够同时提取迷迭香中的水溶性成分RA和脂溶性成分CA,得率高且能够保持良好的抗氧化活性,是一种绿色、环保、高效的迷迭香抗氧化剂提取方法。     

Fracture properties of potato crisps

The Weibull modulus of potato crisps is about 4, comparable with ceramic materials, with a characteristic strength of about 1.5 MPa. This combination of brittleness and weakness gives crispness. The critical stress intensity factor (K_IC) and the energy of fracture (R) are around 0.12 MPa and 45 J m^–2, respectively. There was no significant difference between the material values obtained for the fracture properties of crisps of a range of subjective ‘crispness’ as measured by a trained organoleptic panel. Crispness is ranked by the structural bending strength. Centrally loaded plate tests give qualitative evaluation of crispness. Both these tests could be used in quality control, with advantage over organoleptic tests such as cost, the time required, objectivity, consistency of results, the relation of the measured parameters to standard materials tests and the relatively small amount of material that is needed by comparison.     

迷迭香酸的生理活性功能及其来源研究进展

本研究采用绿色环保的亚临界水提取技术从紫苏籽粕中提取迷迭香酸。在单因素实验基础上,采用3因素3水平的响应面分析法,以迷迭香酸的提取得率为响应值,以提取温度（140~180 ℃）、提取时间（20~40 min）、料液比（1:30~1:50 g/mL）为自变量,确定亚临界水提取的最佳工艺参数。同时,比较了亚临界水提取法和几种常规提取法对迷迭香酸提取得率及其抗氧化活性（DPPH和ABTS自由基清除力）的影响。结果表明,优化后的亚临界水提取工艺参数为：提取温度163 ℃、提取时间30 min、料液比1:41 g/mL;此条件下,迷迭香酸的提取得率为4.91±0.16 mg/g dw,其清除DPPH和ABTS自由基能力的V_C当量分别为10.62和13.46 mgV_C/g dw,均显著高（P<0.05）于几种常规提取法。此外,扫描电子显微镜（SEM）结果显示,亚临界水提取后的紫苏籽粕粉末结构更疏松,说明亚临界水更有利于迷迭香酸的提取。     

Kinetic modelling: A tool to predict the formation of acrylamide in potato crisps

Three empirical models were used to fit the formation of acrylamide in crisps of three different cold-sweetened potato genotypes, fried under the same experimental conditions. Statistical methods were used to compare the performance of the models, with the “Logistic-Exponential” model performing the best. The obtained model parameters for the formation of acrylamide showed improvement in precision compared to an earlier study, the precision of the parameter estimates for the degradation of acrylamide was still problematic. Nevertheless, the predictive capacity of the “Logistic-Exponential” model was tested, as this model showed a strong correlation between parameter a and the reducing sugar content of the raw potato. The predictions from this model for the formation of acrylamide in potato crisps were close to earlier reported experimental values. Therefore, the use of the “Logistic-Exponential” model as a tool to predict acrylamide in potato crisps seems promising and should be developed further.