Effect of pre-drying and par-frying conditions on the crispness of French fries

An experimental design was used to study the effect of pre-drying (to 10, 15 and 20% weight loss) and par-frying conditions (160, 170 and 180 °C) on the crispness of French fries. Par-frying time was adjusted with a software program to obtain equal moisture content and internal texture for all samples. Crispness was evaluated with a sensory panel. Furthermore, samples were analysed with a texture analyser and with confocal scanning laser microscopy (CSLM). Par-frying at 180 °C resulted in a crispier product than at 160 and 170 °C. Pre-drying to 20% weight loss lead to blisters and reduced crispness in comparison with pre-drying to 10 and 15% weight loss. Instrumental texture measurements showed a good correlation with sensory crispness. Large differences in cell structure, such as blisters, could be observed with CSLM. CSLM was useful to explain results from the instrumental and sensory texture evaluation.     

紫色马铃薯薯条生产工艺的研究

以紫色马铃薯为原料,对丙烯酰胺含量低,色素保留较好的紫色马铃薯薯条生产工艺进行研究,得到最佳工艺为烫漂处理+微波真空冷冻。烫漂处理中最优护色剂组合为L-半胱氨酸浓度0.08%、柠檬酸浓度0.1%、氯化钙浓度125×10-6g/mL,浸泡时间10min;最佳烫漂温度70℃;烫漂时间5min。该工艺成品中未检出丙烯酰胺,色泽(E值)可降低到92.8739±5.3234。     

番薯片热风与微波联合干燥特性及品质评价

对番薯片热风与微波联合干燥特性进行研究,并对脱水后番薯片的色泽、复水比、干燥时间及能耗进行了分析。结果表明:番薯片热风-微波联合干燥的热风段和微波段都分为升速和降速阶段。微波-热风联合干燥的微波段分为升速、恒速和降速阶段,热风段只有降速阶段;联合干燥的热风段都可采用Verma模型进行描述。热风-微波联合干燥的微波段采用Logarithmic模型描述,微波-热风联合干燥的微波段采用Page模型描述;热风-微波联合干燥方式所得番薯片L*值为72.86±2.29,a*值和b*值分别为11.02±2.73、38.65±4.45,褐变不明显,β-胡萝卜素保留效果较好。复水比为2.17±0.03,干燥时间为（104±4.93）min,能耗为（18.71±1.05）k W·h/kg,与热风干燥相比,干燥时间缩短55%,能耗降低64%。先热风后微波的联合干燥方式具有干燥产品品质好,能耗较低的特点,更适合于番薯片的干燥。      

生态净养和传统养殖乌鳢的营养品质研究

乌鳢是一种营养价值较高的淡水鱼。在传统商品鱼养殖后期采用“生态净养”技术,降低产品脂肪含量,去除“土腥味”、提高肉质紧实度,使商品乌鳢品质提升。结果表明：净化组肥满度(p<0.05)和水分、粗脂肪(p<0.01)均高于池塘组。均检测出17种氨基酸,必需氨基酸、鲜味氨基酸含量普遍高于传统池塘。穿刺模式下硬度、弹性、破裂强度均高于池塘组,差异极显著(p<0.01)；触碰模式中净化组硬度、咀嚼性、回复性高于池塘组差异显著(p<0.05),净化组挥发性气味物质与五点快感评价法总体高于传统池塘。Fe、Cu、Zn、p等矿物元素均高于池塘组。综上,生态净养养殖乌鳢品质特性更佳,更符合消费者的需求,有良好市场前景。     

Modeling and minimizing process time of combined convective and vacuum drying of mushrooms and parsley

The aim of this work was to obtain a technological and economic alternative for mushroom and parsley dehydration combining convective and vacuum drying. Depending of product, this combination of technologies allows minimization of total drying time and avoids negative effects on quality of thermo-sensitive products during drying. Experimental drying curves were determined in a cross-flow convective dryer and in a cabinet vacuum dryer at 35, 45 and 55 °C. The most appropriate theoretical models were obtained and applied for combined processes in order to minimize the overall drying time and avoid final product damage. For parsley at the highest temperature (45 °C), reductions of 63% and 16% in drying time were observed with the combined drying process compared to the sole convective and sole vacuum drying, respectively. This reduction in process time was obtained when dryer change was done at the intermediate moisture condition that determines the highest drying rate during the whole combined process of convective and vacuum drying. For mushrooms, convective drying throughout the process, at the highest temperature (55 °C) compatible with product visual quality, minimized drying time.     

The effects of enzymes on fat content and texture of French fries

The purpose of the present investigation was to study the changes in the microstructure of potato cells during French fries processing with the use of enzymes and to find the impact of the enzymes on fat content and texture of French fries. The samples for laboratory studies were of potato strips and French fries, collected from five locations of the technological line.     

Vacuum frying of high-quality fruit and vegetable-based snacks

Sweet potato, green beans, Tommy Atkins mango, and blue potato were fried in a vacuum frying process at a temperature of 120-130 ± 1°C. Before frying, green beans and mango slices were soaked in a 50% maltodextrine 0.15% citric acid solution. The products were also fried in a traditional (atmospheric pressure) fryer at 160-165 ± 1°C for 4 min. A 30-member consumer panel rated the sensory quality of both types of fried snacks using a 1-9 hedonic scale. Compared with traditional frying, oil content of vacuum-fried sweet-potato chips and green beans was 24% and 16% lower, respectively. Blue potato and mango chips had 6% and 5% more oil, respectively, than the traditional-fried samples. Anthocyanin (mg/100 g d.b.) of vacuum-fried blue potato chips was 60% higher. Final total carotenoids (mg/g d.b.) were higher by 18% for green beans, 19% for mango chips, and by 51% for sweet-potato chips. Sensory panelists overwhelmingly preferred (p < 0.05) the vacuum-fried products for color, texture, taste, and overall quality. Most of the products retained or accentuated their original colors when fried under vacuum. The traditional-fried products showed excessive darkening and scorching. These results support the applicability of vacuum frying technology to provide high-quality fruit and vegetable snacks.     

Consumer Acceptability and Quality Evaluation of Potato Strips Baked in a Radiant Wall Oven

Instrumental and sensory quality of potato strips baked in a radiant wall oven was evaluated and compared to deep-fat fried and conventional oven baked samples. Even though radiant wall oven baked potato strips had one-fourth the fat content of the deep-fat fried samples, there was no significant difference in chroma, cutting and puncture force of radiant wall oven baked and deep-fat fried samples. Consumer acceptability of radiant wall oven baked potato strips was 65.7 and 85.7% before and after revealing the nutrition facts, respectively. Both were lower than acceptability of deep-fat fried samples. However, 36.5% of consumers were willing to purchase radiant wall oven baked samples.     

Color,Mechanical, and Microstructural Properties of Vacuum Assisted Microwave Dried Saskatoon Berries

Saskatoon berries were dried using a vacuum assisted microwave technique. Central composite rotate design and response surface methodology were used to develop the regression models and to study the influence of drying processing variables (microwave power, drying time, and fruit load) on color, mechanical properties, and microstructure of dried berries. All the three variables had significant effects on the above mentioned properties (p< 0.05). Drying affected the color at variable levels and increased the lightness of dried berries compared to frozen berries. Hardness, gumminess, and chewiness of dried berries increased and springiness and cohesiveness of dried berries decreased with microwave power and drying time. The porosity and the destruction level in the microstructure of dried berries increased with the microwave power. The findings of this study will be useful to identify desirable microwave-vacuum drying operating conditions for targeted dried Saskatoon berry products.     

Effects of vacuum and microwave freeze drying on microstructure and quality of potato slices

Potato slices immersed in 0.5% CaCl₂ solution for 10 min were examined using light microscopy for their microstructure in frozen state before drying, during the sublimation drying stage, in the desorption drying stage and in the final dried form. Additionally, the final dried product was also tested for vitamin C content, color, starch content, texture and sugar content. Experiments were carried out using conventional vacuum freeze dryer as well as a microwave freeze dryer. Results for both unblanched and blanched potato tissues, crystal growth during sublimation drying stage was observed to cause structural damage to the cell walls. Blanched tissue suffered more damage during the freezing process. Interestingly, microwave freeze drying yielded product similar in quality to that obtained in vacuum freeze drying with conductive heating.     

果蔬微波真空干燥（MVD）技术研究进展

为了提高甘薯干燥效率和改善产品品质,本文采用微波真空干燥（MVD）技术,研究了超声处理（US）、渗透脱水（OD）、超声辅助渗透（USOD）、真空辅助渗透（VAOD）和超声/真空辅助渗透（VUOD）对甘薯切片干燥动力学、微观结构、孔隙特征及理化性质的影响。采用Weibull分布函数和Dincer模型对干燥曲线进行拟合,并结合尺度参数（α）、形状参数（β）、滞后因子（G）、干燥系数（S）、毕渥数（Bi）探讨了MVD甘薯切片干燥过程的热、质传递机制。结果表明：相比其他处理,USOD和VUOD可显著提高甘薯切片的水分流失率（WL）和固形物增加率（SG）（P<0.05）。Weibull分布函数和Dincer模型对MVD甘薯切片的干燥曲线具有较好的拟合效果。模型参数（α, β, G, S）结果表明,经USOD处理的MVD甘薯切片干燥效率最高,加速阶段历时最短;毕渥数（Bi）处于0.243~3.617之间,表明MVD干燥过程甘薯切片温度变化由内部传导热阻和表面对流热阻共同控制。基于Weibull和Dincer模型计算获得的水分扩散系数D_cal和D_eff分别为7.986×10⁻⁸~1.249×10⁻⁷和1.508×10⁻⁸~8.272×10⁻⁸ m²/s,且均是USOD样品最大,OD最小。USOD和VUOD甘薯切片呈现蜂窝状、多孔结构,其中VUOD样品孔隙率最大（为33.30%）,而USOD样品平均孔径最小（仅为164.50 nm）、迂曲度最大（为41.97）。相比其它预处理,USOD和VUOD处理显著提升了MVD甘薯切片的复水性能（P<0.05）,降低了体收缩率,较好地保持了原有色泽,缩小了色差。研究结果可为甘薯切片的微波真空干燥条件筛选和品质调控提供参考。     

Computer vision-based image analysis for the estimation of acrylamide concentrations of potato chips and french fries

In this study, digital colour images of fried potato chips and french fries were analyzed to estimate acrylamide levels based on the correlation with analyses using liquid chromatography-mass spectrometry. In fried potato images, bright yellow (Region 1), yellowish brown (Region 2) and darker brown (Region 3) regions were clearly visible, having different kinds of image pixels with characteristic mean values of red, green and blue components. Pixels of the fried potato image were classified into three sets (Set 1, Set 2 and Set 3) by means of semi-automatic and automatic segmentation. There was a strong correlation between acrylamide concentration and NA2 value, which is defined as the number of pixels in Set 2 divided by the total number of pixels of the entire fried potato image. To verify the applicability of this approach, a linear regression equation was used to estimate the acrylamide concentrations of a number of commercial potato chips and home-made french fries. Mean differences between the measured and predicted acrylamide concentrations were found to be +4 ± 14% and −14 ± 24% for commercial potato chips and home-made french fries, respectively.     

Storage and packaging effects on sensory and color characteristics of ground beef

Effects of irradiation (2 kGy) of ground beef patties from trimmings stored aerobically for 0 or 6 days on lean color, odor, and sensory attributes were investigated. Beef trimings were coarse ground and split into 2 groups. Group one was fine ground, pattied, and packaged immediately; group-two was stored 6 days then fine ground, pattied, and packaged. Irradiated beef patties had greater (P<0.05) off-odors, and off-flavors, lower (P<0.05) CIE L^*, a^* and b^* and saturation indexes values (P<0.05) after four days of storage at 0±1 °C. Irradiation of patties produced from trimmings aged an extra 6 days resulted in increased (P<0.05) saturation indexes and b^* values, but not off-odors when compared to non-aged and irradiated patties. Thus, the production of irradiated beef patties should utilize beef trimmings with the shortest postmortem aging time and a dose of less than 2 kGy to minimize discoloration and off-odors.     

Changes of polysaccharide content and texture of potato during French fries production

The purpose of the present study was to determine the changes in non-starch polysaccharide and lignin contents of potato during French fries production and also the relationship between the texture of the finished product and half-products, as a result of processing at each stage under investigation. The samples for laboratory studies were taken from potato tubers, strips and French fries collected from nine locations of a technological line. The greatest changes in non-starch polysaccharide content and texture of potatoes resulted from blanching and frying. The texture of French fries was mainly affected by pectin and cellulose. The texture of French fries can be predicted from the measurements of the texture of potato strips after blanching.     

干燥工艺对低温肉肠品质的影响

以猪肉、鱼浆为主要原料制备低温肉肠,对其干燥工艺条件进行了优化,探讨了热风干燥时间、微波功率、微波时间对低温肉肠品质的影响。结果表明,随着热风干燥时间的延长,肉肠的形态、色泽、滋味和口感均呈上升趋势且内外水分差减小,再经过微波处理,有助于平衡内外水分,提高色度均匀性和感官品质,然而时间过长会造成肉肠口感变差、硬度过大、色度下降等。该低温肉肠的最适干燥工艺为采用55℃的热风干燥箱干燥14h后,用250W的微波干燥90s。      

热风干燥和微波干燥对草鱼肉品质的影响

目的 研究微波干燥和热风干燥对草鱼片品质的影响。方法 采用50℃热风干燥和400 W微波干燥对草鱼片进行干燥, 对草鱼片干燥过程中水分含量、质构、色度、脂肪及蛋白质相对含量等进行表征。借助气相色谱-质谱法(gas chromatography-mass spectrometry, GC-MS)研究不同干燥条件对草鱼片挥发性物质的影响。结果 两种干燥过程中草鱼片水分含量下降, 硬度增加, 亮度降低, 同时鱼肉蛋白质和脂肪的相对湿基含量增加。其中, 热风干燥时间6~8 h, 微波干燥时间4~5 min的草鱼片硬度和咀嚼性较大、弹性适中、红度值(a*)较大。两种干燥方式中草鱼片挥发性物质的种类和含量均增加, 微波干燥和热风干燥共分别检出52种和36种挥发性物质。微波干燥产生了较多的醛类、不饱和醇类、酮类物质, 对鱼肉风味有较大影响。结论 400 W微波干燥较50℃热风干燥更适用于实际加工过程中的快速干燥工艺, 且能够较好的改善鱼肉风味。     

不同干燥方式对甘薯叶理化特性和抗氧化能力的影响

目的 探究三种不同干燥方式(微波干燥、热风干燥、冷冻干燥)对甘薯叶物化特性的影响。方法 以新鲜甘薯叶为原料,探究三种不同干燥方式对甘薯叶基本成分(水分、蛋白质、总膳食纤维、粗脂肪、可溶性糖、总酚、总黄酮和绿原酸含量)、物化特性(色度、微观结构、胆固醇吸附能力、持水力、持油力和葡萄糖吸附能力)和抗氧化活性(DPPH.清除率、ABTS法自由基抑制率、总还原力和.OH清除能力)以及酚类物质的组成等影响。结果 不同干燥方式对甘薯叶基本成分的影响中,利用热风干燥的甘薯叶水分含量最高,为7.96 g/100 g;冷冻干燥含水量最低,为7.29 g/100 g;冷冻干燥的蛋白质含量、粗脂肪、总酚、总黄酮以及绿原酸含量最高,分别为31.39 g/100 g、3.43 g/100 g、50.73 mg CAE/g DW、18.49 mg RE/g DW、7.05 mg/g DW;热风干燥的总纤维含量最高,为28.8 g/100 g。不同干燥方式对甘薯叶理化指标的影响中,利用冷冻干燥的甘薯叶色泽品质明显优于热风干燥和微波干燥;热风干燥的胆固醇吸附能力和持油力最强,分别为0.23 mg/mL,1.54 g/g;冷冻干燥的持水力和葡萄糖吸附能力最优,分别为7.33 g/g和12.00 mmol/g。抗氧化性上,不同方法测定的抗氧化能力都表现为冷冻干燥＞微波干燥＞热风干燥,冷冻干燥的总还原力、DPPH.清除能力、.OH清除能力、ABTS+^{清除率分别高达}83.34、41.28、9.17、27.21 mg Vc/g。结论 冷冻干燥最适合用来对甘薯叶进行干燥处理。     

Comparison of the effect of microwave freeze drying and microwave vacuum drying upon the process and quality characteristics of potato/banana re‐structured chips

This study investigated the drying characteristics of microwave freeze‐drying (MFD)/microwave vacuum drying (MVD) of banana/potato restructured chips of varying proportion and microwave power. The results showed the MFD drying time had a maximum one‐hour time difference between the samples treated with 2 W g^?1 and 3 W g^?1 microwave power; and the higher potato content samples have about 30 min predominance than low potato content samples in drying time and the total drying time of MVD samples was less than 60 min. For the rehydration ratio, MFD samples were far superior to the MVD samples. The MFD samples had more than 4.5 rehydration ratio. The data of the colour difference metre showed that 3 W g^?1 microwave power would make samples slightly charred. The biggest differences between the MFD and MVD chips lie in their texture and shape; the hardness of MVD samples was 30.86 N, thrice higher than MFD samples.     

微波干燥条件对杏脯干燥特性与品质的影响

目的:提高杏脯的干燥效率及产品品质。方法:分别用转盘式微波炉(RMD)和微波对流耦合干燥机(MCD)干燥杏脯,考察微波功率、微波发射方式、切分程度及物料是否转动对杏脯干燥特性、焦化率、色值、感官品质及复水特性的影响,并与传统热风干燥(HD)进行比较。结果:与HD的1 040 min(16块)和840 min(48块)相比,微波干燥显著缩短干燥时间,不同微波干燥条件下所需的干燥时间为40～400 min;脉冲比越大或功率越高或物料尺寸越大,干燥所用时间越短,在MCD中控温微波干燥耗时最长。无论是在RMD还是不控温MCD中静态干燥,杏脯均出现严重的烧焦现象,焦化率为17%～100%,物料转动时焦化率高于静态干燥的,而在MCD中控温静态干燥避免了物料的烧焦现象,且MCD中控温静态干燥的杏脯色值和感官评价最接近HD的,复水比与HD仅相差3.45%～5.17%,获得最高的感官评价分(87.2分)。结论:MCD中控温静态干燥可以作为杏脯的高效干燥方法。     

Effects of food gums and pre-drying on fat content of fabricated fried chips

Deep-frying contributes to the unique taste and texture of fried products. However, they are low in nutritional value. Food industries actively trying to find ways to reduce the fat content while maintaining organoleptic properties of fried foods. In this work, effects of pre-drying and adding food gums on the moisture and fat contents of chips were evaluated. The chips were pre-dried for 60 and 90 min, and gellan gum, guar gum, methylcellulose and xanthan gum were added at the concentration of 0.25, 0.75, 1 and 2 % w/w. The xanthan gum was the most effective gum for fat reduction. The addition of 0.25 % w/w xanthan gum and at 90 min pre-drying reduced the fat content from 20 % (control) to 15 % w/w. The results also indicated that the reduction of moisture content after frying was not affected by the type of gums but the method of pre-drying.