微波辅助热风干燥预处理对油炸紫薯片品质的影响

为研究微波辅助热风干燥预处理对油炸紫薯片品质的影响,以厚度为3 mm的新鲜紫薯片为对象,首先采用不同微波功率(259、280、358 W)辅助热风(50、60、70 ℃)干燥方式对紫薯片进行预干燥,对不同微波功率(259、280、358 W)干燥后的紫薯片油炸8、3.5、2.5 min,研究紫薯片预处理过程的干燥特性及花青素含量,以及油炸紫薯片产品的色泽、脆度、硬度和脂肪含量等。结果表明:随着微波预处理功率的升高,紫薯片达到干燥终点的时间缩短(90 min以上),平均干燥速率显著提高;并且热风干燥温度越高,微波预处理对干燥效率的促进作用也越明显。而低功率(259 W)的微波辅助50 ℃热风干燥联用更有利于干燥紫薯片花青素的留存;较低功率(259、289 W)的微波预处理不仅在保护产品颜色上具有优势,还可以使得油炸紫薯片更高的硬度和更好的脆性。在不同微波预处理功率下,油炸紫薯片的脂肪含量最低值基本一致。本研究可为微波辅助热风技术在干燥紫薯及其他农产品干燥中的应用提供参考。     

微波生产低油马铃薯片的工艺条件的探讨

通过单因素试验,对利用微波生产低油马铃薯片工艺中影响产品脆度、色泽和含油量的一些因素进行了探讨。结果表明:利用微波生产马铃薯片可以降低薯片含油量到20%以下;干燥前食盐水溶液浸泡处理(1.5%～2.0%食盐水溶液浸泡5min)和涂油前用豆奶粉裹衣处理,均能降低产品的含油量,提高马铃薯片的脆度;同时,适量的豆奶粉裹衣处理,能赋予产品良好的色泽,豆奶粉的用量6%比较适宜;冷冻处理能加深产品的色泽,但是对产品的脆度和含油量的影响不大。     

两种干燥方式对马铃薯全粉营养品质和加工特性的影响

以新鲜"云薯304"切片后,采用漂烫冻干、不漂烫冻干、漂烫烘干和不漂烫烘干四种工艺条件制备干片,再经研磨粉碎制成半生的马铃薯全粉,研究不同工艺条件下全粉的营养品质和加工特性。结果表明:采用漂烫冻干工艺,马铃薯全粉的颜色与鲜马铃薯颜色最接近,制备的马铃薯全粉还原糖含量最低,为0.15%;蛋白质含量(9.01%)、总淀粉含量(69.12%)、直链淀粉含量(31.60%)与其他三种工艺处理无显著差异;从加工特性上看马铃薯全粉的持水力(5.27 g水/g全粉)和持油力(1.55 g油/g全粉)、透光率(83.43%)和各个温度下的膨胀度(50℃:9.32 g/g;60℃:11.98 g/g;70℃:13.11 g/g;80℃:15.35 g/g;90℃:12.50 g/g)均最高,都显著高于其他三种工艺(P<0.05);且凝胶流程最短,为10.96 mm。因此,可认为漂烫冻干是制备马铃薯全粉的最优工艺。     

响应面法优化甘薯脆片干燥工艺

为探究甘薯脆片热泵干燥最佳工艺,在单因素试验基础上,以烘干温度、烘干时间、切片厚度、汽漂时间为影响因素,以含油率及感官评分为响应值,用Box-Behnken试验设计建立响应面分析模型。结果表明,甘薯脆片烘干最佳工艺为:烘干温度74℃、切片厚度2.7 mm、汽漂时间3 min,烘干时间为3.5 h,在此优化条件下,甘薯脆片油炸后感官评分为88.75分,含油率为7.84%,在此条件下得到的产品色香味俱全。     

Physico-chemical changes during different stages of MFD/FD banana chips

Microwave freeze drying (MFD) normally contains three stages, i.e., pre-freeze stage, primary drying stage and secondary drying stage, just as in conventional freeze drying. This research examines the variations of structure, starch content, reducing sugar content, color change as well as expansion ratio during these stages of microwave freeze drying banana chips. Results show that biggest changes are found at the primary drying stage in the banana slices’ starch content, reduced sugar content, their structure and their changed colors while the biggest change of expansion ratio occurs at the secondary drying stage. Similar results can also be obtained for FD samples. Thus it is concluded that the primary stage can do most damage to the banana chips.     

前处理对甘薯变温压差膨化效果影响

研究不同切片厚度、热烫、冷冻和浸渍等4个因素对甘薯变温压差膨化干燥产品含水率、硬度、色泽和复水比的影响。结果表明:甘薯切片的最佳厚度为2 mm,物料经浸渍处理所得产品品质较优;糖液浸渍预处理使物料加速失水,对物料色泽和外形的保持有显著的作用;在果葡糖浆、麦芽糖浆、麦芽糖醇中,选用麦芽糖浆作为预处理的浸渍溶液,且浓度为15%,浸渍时间为8 h产品质量较好。     

不同加工方式对柿子脆片物理特性及营养品质的比较分析

为探究不同加工方式对柿子脆片物理特性及营养品质的影响,采用真空油炸、真空微波、压差膨化、微波干燥四种加工方式对柿子脆片进行加工,并探讨不同加工方式对柿子脆片色泽、硬度、脆度、复水比、体积、微观结构及总糖、总酸、维生素C和蛋白质等的影响。研究表明四种不同加工方式对柿子脆片物理特性及营养品质影响显著（p<0.05）。物理特性方面,压差膨化干燥整体色泽呈亮黄色,结构疏松,硬度适中,脆度最好,口感酥脆,复水性较好。营养品质方面,压差膨化干燥柿子片总糖含量（18.91%）、维生素C含量（129.80 mg/100 g）均优于其他三种加工方式,蛋白质含量（2.17%）和总酸含量（1.16%）较低,但比蛋白质含量最高的真空微波干燥仅少0.12%,比总酸含量最高的微波干燥仅少0.74%。综合分析,压差膨化干燥优于其他三种加工方式,是柿子脆片加工的首选方式。     

不同加工处理时β-淀粉酶对紫甘薯淀粉及还原糖含量影响

根据林–贝双倒数作图法求得紫甘薯β–淀粉酶米氏常数为2.25×10–5mol/L,说明其具有较强水解淀粉能力。通过比较烘干法、晒干法、蒸煮法、烘烤法、微波加热法、油炸法六种不同加工方法对紫甘薯淀粉和还原糖含量影响可知,加工后淀粉含量下降1.02%~9.98%,还原糖含量增加2.60%~31.07%。对于紫甘薯不同加工方法,烘干处理比晒干更易于糖化,蒸煮与烘烤相近,但其糖化强度都不及烘晒处理;紫甘薯加工处理后,淀粉和还原糖含量变化幅度有较大差异,与其所含β–淀粉酶活性作用发挥呈有直接关系。     

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;最优油炸工艺条件为:预油炸温度149 ℃,预油炸时间98 s,二次油炸温度190 ℃,在该条件下测定含油率的平均值达(17.1±0.2)%。该工艺条件下制得的甘薯脆片含油率低于同类产品,外观亮黄,无焦糊现象。     

Modeling the Contribution of Sugars, Ascorbic Acid, Chlorogenic Acid and Amino Acids to Non-enzymatic Browning of Potato Chips

The contribution of potato constituents to color development in fried chips was evaluated using model systems. Soluble constituents of potato slices were removed using water and ethanol. Leached slices were infiltrated with pH 6.2 solutions containing sucrose, reducing sugars (glucose and fructose), ascorbic, chlorogenic and amino acids (asparagine and glutamine) in quantities typical for potatoes. Infiltrated slice composition was evaluated by HPLC. Slices were fried and the color measured. Reducing sugars showed linear association with L* and hue angle and quadratic relationship with chroma of chips. Ascorbic acid affected chip color at low reducing sugar levels (40 mg/100g tuber); sucrose also contributed to chip color development.     

鱼糜-淀粉脆片压差膨化加工工艺研究

以糯米淀粉和鱼糜为主要原料,采用压差膨化技术制备鱼糜-淀粉脆片。以硬度、脆性、膨化率、色度和感官评分为评价指标,探讨鱼糜添加量、油脂添加量、盐添加量、糖添加量以及干燥时间对鱼糜-淀粉脆片品质的影响。结果表明,随着鱼糜含量的增加,脆片的膨化率下降而硬度上升;随着油脂含量的增加,脆片的膨化率和白度增大;随着糖含量的增加,脆片白度下降;随着盐含量的增加,脆片膨化率下降;在不同的干燥时间下,脆片的膨化率、质构、色泽与感官都发生明显变化。最后得到鱼糜-淀粉脆片的工艺参数为鱼糜添加量25%,油脂添加量5%,盐添加量1.2%,糖添加量1.2%,干燥3.5 h。     

不同马铃薯品种对鲜切油炸薯片中丙烯酰胺的影响

研究11个不同马铃薯品种,在相同的油炸条件下进行鲜切油炸薯片实验,采用液相-质谱联用检测其不同品种鲜切油炸薯片的丙烯酰胺含量,结合品种的还原糖含量,对丙烯酰胺含量进行分析。方法：热烫60s,表面干燥,180℃油炸100s,脱油,样品预处理,待测。结果：在相同油炸实验的基础上,检测出丙烯酰胺含量较低的是D519、陇薯3号、中薯7号、LK99等;丙烯酰胺含量较高的是中薯8号、夏波蒂、中薯3号等,并且丙烯酰胺含量与品种的还原糖含量走向基本相似。     

热烫预处理降低鲜切油炸薯片中丙烯酰胺的工艺优化研究

研究热烫预处理对鲜切油炸薯片中丙烯酰胺的影响和薯片油炸工艺优化。在相同条件下,分别对原料进行热烫和非热烫处理,在不同油炸温度和时间条件下进行油炸试验,采用DNS法测还原糖,液质联用法检测薯片中丙烯酰胺含量。结果表明,通过对切片的马铃薯进行热烫处理,即75℃热烫150s,能明显降低还原糖含量,160℃油炸120s,可降低丙烯酰胺含量至67.18μg/kg。     

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.     

Grading of Potato Chips According to Their Sensory Quality Determined by Color

Potato chips were classified in quality categories according to their color after frying at oil temperatures (120, 140, 160, and 180 ± 1 °C) and undergoing some pre-treatments (control or unblanching, blanching, and blanching plus drying). For each oil temperature, six time intervals were considered since the beginning of the frying process until the corresponding time at which potato slices reached a moisture content of 2%. In order to define quality categories according to the surface color, we worked with 79 frequent consumers of potato chips who classified the color scores of the potato chip photographs located in a standard color chart in the following categories: (1) desirable color, (2) still acceptable color and (3) nondesirable color. A sensory panel was formed with 12 judges who were selected according to simple tests of color ordering. This sensory panel evaluated the samples processed at different oil temperatures, frying times, and pre-treatments based on the standard color chart previously mentioned. For each measured point, the score from the color standard chart indicated for more than 50% of the panel members was selected. Finally, time-temperature modeling was achieved in order to get potato chip with the best color surface for the three pre-treatments tested.     

马铃薯片间歇微波真空干燥工艺优化

针对微波真空干燥马铃薯片易产生焦糊的问题,采用间歇式微波真空干燥工艺,运用图像处理中RGB模型表示干燥后马铃薯片色泽的变化情况,以干制品焦糊程度和图像的RGB强度为主要指标,分析间歇方式、微波功率、切片厚度和真空度对马铃薯片微波干燥品质的影响。结果表明,间歇干燥的方式有利于减少微波干燥焦糊现象,RGB强度越大,焦糊越少,色泽越好,最佳干燥工艺为:微波加热60 s、间歇60 s、微波功率300 W、切片厚度3 mm和真空度0.08 MPa。试验结果可为马铃薯片间歇微波真空干燥过程焦糊分析、工艺参数优化和在线检测提供参考。     

Effects of Initial Moisture Content on the Oil Absorption Behavior of Potato Chips During Frying Process

During frying process, whether and how moisture content in materials affects oil absorption remain unclear. Herein, we provided direct evidence suggesting that although the initial moisture content had no significant effect either on the final oil content or oil fraction, the moisture content did greatly affect the rate of oil absorption. We analyzed the total oil (TO), surface oil (SO), structural oil (STO), penetrated surface oil (PSO), and oil distribution during frying process in once-fried and twice-fried potato chips, and found that SO fraction was lowest (about 0.90-1.66 %) among three different fractions of TO, while PSO was the dominant section (about 50 %) for TO. Surprisingly, there were no significant difference among the final TO, SO, STO, and PSO for two kinds potato chips (P > 0.05), a finding suggesting that the initial moisture content itself might have no effect on oil absorption. Compared with once-fried potato chips, twice-fried chips much quicker (around sevenfold) reached equilibrium at 180 °C, which might be attributed to no inner resistance of water evaporation in twice-fried potato chips. More importantly, our confocal laser scanning microscopy (CLSM) inspection established that oil of twice-fried chips entered the core faster than once-fried chips. Oil followed the cell shapes and located in cell walls and inside the intercellular spaces for both samples. Taken together, this study provided compelling new data to clarify the relationship between the initial moisture content and oil absorption during frying process, and laid the groundwork for introducing a pre-drying strategy to frying process in food industry.     

Spezielle Probleme bei der Chips-Herstellung

Special Problems of Chips Manufacturing. This investigation deals with the problems manufacturing potato chips referring to the quality. A manufacturer of chips has realized some experiments in order to enlarge the spectrum of potato varieties, which are suitable for producing chips of good quality. Beside the results of these experiments some other problems have been solved, for example the degree of damage. Two of the most important characteristics of chips quality are the colour and the oil content. It is reported about tests showing that within the single classes of specific gravity the dry matter content, and depending on this dry matter content, the reducing sugar content is spreading very much within one potato variety. The data from these experiments show a correlation between dry matter content and chips colour within one variety. The increasing of dry matter content implies brightening up of the chips colour. Furthermore it is reported about the important correlation between dry matter content and relation of starch to nonstarch material and the quality characteristics like oil content and yield of chips. The influence of the manufacturing process on the quality characteristics has been examined.     

应用Ca~(++)和Zn~(++)抑制马铃薯片油炸脱水过程褐变的研究

马铃薯油炸脱水过程的褐变主要是由于氨基酸和还原糖之间的美拉德反应的结果。Zn~#和Ca~#作为中心离子与马铃薯块茎中所含的游离氨基酸配合构成配合物,抑制美拉德反应或延缓它的感应期(Induction period),从而获得改善油炸马铃薯片色泽的效果。还原糖含量为0.67％～2.06％的马铃薯切片,用0.010M CaCl_2和0.015M ZnSO_4混合液处理20分钟,可获得满意的浅淡色泽的油炸马铃薯片。     

不同干燥方式对橄榄果粉品质的影响

比较微波干燥、热风干燥、真空干燥以及真空冷冻干燥对橄榄果粉外观色泽、物理特性、营养成分及微观结构等品质的影响。结果表明:真空冷冻干燥橄榄果粉色泽较佳,具有较高亮度和最低的红绿度,最接近鲜食橄榄绿色色泽;热风干燥和真空干燥所得果粉吸油性较低,吸湿性较高,热风干燥的果粉堆积密度和溶解度均最高,真空冷冻干燥的果粉堆积密度最低,吸湿率低,复水性、流动性、吸油性和溶解度均较高,微波干燥的果粉含水率最高,复水性、吸湿率、堆积密度、吸油性和溶解度均较低;微波干燥的还原糖、总酸含量损失较小,热风干燥的类黄酮损失较小,真空干燥的总糖和总酚含量损失较小,真空冷冻干燥的蛋白质含量损失较小。扫描电镜观察微观结构发现微波干燥和真空冷冻干燥果粉颗粒间空隙大,组织较光滑完整,皱缩少,热风干燥和真空干燥果粉颗粒间空隙小,部分皱缩。通过主成分分析品质综合得分结果为:真空冷冻干燥>真空干燥>热风干燥>微波干燥。