Effect of Microwave Frying on Acrylamide Generation,Mass Transfer,Color, and Texture in French Fries

The objective of this work was to evaluate the effect of microwave power on acrylamide generation, as well as moisture and oil fluxes and quality attributes of microwave-fried potatoes. Concretely, 25 g of potato strips, in 250 mL of fresh oil (at room temperature), were subjected to three different microwave powers (315, 430, and 600 W) in a conventional microwave oven. Microwave frying resulted in an acrylamide reduction ranged from 37 to 83% compared to deep-oil frying. Microwave-fried French fries presented lower moisture and higher fat content than deep-oil fried potatoes. Concretely, microwave-fried potatoes presented values of moisture and texture more similar to potato chips than French fries, nonetheless with lower fat levels (less than 20 g/100 g wb) and acrylamide content (lower than 100 μg/kg wb) at the reference time. This study presents an alternative way of frying to address the production of healthier potato chips.     

Screening of acrylamide contents in potato crisps using process variable settings and near-infrared spectroscopy

In order to study the formation of acrylamide in potato crisps during processing, an experimental design was set up. The design variables were drying time (6 levels), frying temperature (2 levels) and frying time (8 levels). The design contained 36 samples, which were analysed for acrylamide contents using LC high-resolution mass spectroscopy (LC-HRMS), and fat contents using the Soxhlet apparatus. Prior to analysis, all potato crisp samples were ground and analysed on an NIRSystems 6500 near-infrared (NIR) spectrometer. The acrylamide contents were modelled by: (i) design variables using multiple linear regression, (ii) NIR spectra using partial least squares regression (PLSR) and (iii) design variables and NIR spectra in combination using a novel technique combining least squares regression on the former, and PLSR on the latter. The results showed that the NIR spectra alone or in combination with the design variables gave better prediction models for acrylamide than the design variables alone. This implies that the spectra contain chemical information that is not purely a result of the processing variables that were investigated in this experiment. NIR spectroscopy is proposed as a possible tool for screening and identification of potato crisps with a high acrylamide content.     

Mapping of Fat and Moisture Distribution in Atlantic Salmon Using Near-Infrared Hyperspectral Imaging

A nondestructive and rapid method using near-infrared (NIR) hyperspectral imaging was investigated to determine the spatial distribution of fat and moisture in Atlantic salmon fillets. Altogether, 100 samples were studied, cutting out from different parts of five whole fillets. For each sample, the hyperspectral image was collected with a pushbroom NIR (899–1,694 nm) hyperspectral imaging system followed by chemical analysis to measure its reference fat and moisture contents. Mean spectrum were extracted from the region of interest inside each hyperspectral image. The quantitative relationships between spectral data and the reference chemical values were successfully developed based on partial least squares (PLS) regression with correlation coefficient of prediction of 0.93 and 0.94, and root mean square error of prediction of 1.24 and 1.06 for fat and moisture, respectively. Then the PLS models were applied pixel-wise to the hyperspectral images of the prediction samples to produce chemical images for visualizing fat and moisture distribution. The results were promising and demonstrated the potential of this technique to predict constituent distribution in salmon fillets.     

On-line, proximate analysis of ground beef directly at a meat grinder outlet

The fat, moisture and protein contents of ground beef were determined on-line by a diffuse reflectance near infrared (NIR) spectroscopy instrument at the outlet of a meat grinder. Beef samples in the range of 6.2–21.7% fat, 59.6–72.9% moisture and 18.1–20.7% protein were studied. Calibrations from samples ground with hole diameters of 4, 8, 13 or 19 mm in the grinder plate were validated. In addition, calibrations of combinations of these samples from the different hole diameters were validated. Prediction errors, expressed as root mean square error of cross validation of the beef samples, were 0.73–1.50% for fat, 0.75–1.33% for moisture and 0.23–0.32% for protein, depending on the hole diameter of the grinder plate. Calibrations from samples ground with the smallest hole diameters gave lowest prediction errors. The present prediction error results are only slightly higher compared to reported prediction error results using conventional at- and off-line NIR instruments.

It is concluded that the on-line NIR prediction results were acceptable for samples ground with grinder plates of 4, 8 or 13 mm hole diameter.     

亲水胶体对真空油炸马铃薯脆片品质的影响

本研究以马铃薯片为原料,将马铃薯片分别浸渍于不同浓度的海藻酸钠(SA)、羧甲基纤维素钠(CMC)、瓜尔豆胶(GU)涂膜液中,以马铃薯脆片水分含量、脂肪含量、硬度、色泽、感官品质为评价指标,并进一步通过扫描电镜研究涂膜处理对真空油炸马铃薯脆片品质的影响。结果表明:SA、CMC、GU均能显著提高马铃薯脆片水分含量(p<0.05),显著降低马铃薯脆片的脂肪含量(p<0.05),SA-1%、CMC-0.75%、GU-1%处理组脂肪含量分别降低了17.22%、40.04%、27.39%;与对照组相比,三种处理组降低了马铃薯脆片的硬度值,对L*、b*值大部分影响差异不显著(p>0.05),亲水胶体处理组样品感官评价得分均较高,CMC-0.75%组得分最高(6.86分);扫描电镜结果表明,CMC能较好地保护马铃薯脆片的细胞结构遭受破坏,防止油脂进入脆片内部。CMC-0.75%处理组能降低马铃薯脆片脂肪含量,感官品质较好。     

Non-Destructive Determination of Fat and Moisture in Whole Atlantic Salmon by Near-Infrared Diffuse Spectroscopy

A near-infrared spectrometer equipped with an interactance optical fiber probe was used to determine the average crude fat and moisture content in the muscle of whole Atlantic salmon (Salmo salar). The fat contents were 8.8—19.2% and moisture 61.0—70.8%, and fish weight range 1.0—5.7 kg. A partial least square regression including 49 salmon resulted in root mean square error of cross validation of 1.12% fat (R = 0.87) and 0.98% moisture (R = 0.86). Results showed that NIR interactance was a suitable non-destructive screening method for fat and moisture content in farmed Atlantic salmon.     

甘薯水分和还原糖协同向量NIR快速检测方法

利用近红外光谱技术建立新鲜甘薯水分和还原糖含量的预测模型,实现快速检测与分析,为甘薯品质分析和种质资源筛选提供便捷。选用不同品系甘薯样品146份,109份作为校正样品,37份作为验证样品。运用不同光谱预处理方法、协同区间偏最小二乘最优波长选择法以及主成分回归和偏最小二乘法建立甘薯水分和还原糖模型。结果显示,所建甘薯水分(还原糖)最优模型的决定系数、预测均方根误差和标准差比率分别为0.974(0.885),1.154(0.270)和6.334(3.148)。表明2种模型具有较好的检测性能,近红外光谱模型的预测值与其相应的化学值有较好的相关性,适用于大批量甘薯选育时水分和还原糖含量的快速检测。     

Color changes and acrylamide formation in fried potato slices

The objective of this work was to study the kinetics of browning during deep-fat frying of blanched and unblanched potato chips by using the dynamic method and to find a relationship between browning development and acrylamide formation. Prior to frying, potato slices were blanched in hot water at 85 °C for 3.5 min. Unblanched slices were used as the control. Control and blanched potato slices (Panda variety, diameter: 37 mm, width: 2.2 mm) were fried at 120, 150 and 180 °C until reaching moisture contents of ∼1.8% (total basis) and their acrylamide content and final color were measured. Color changes were recorded at different sampling times during frying at the three mentioned temperatures using the chromatic redness parameter a¹. Experimental data of surface temperature, moisture content and color change in potato chips during frying were fit to empirical relationships, with correlation coefficients greater than 90%. A first-order rate equation was used to model the kinetics of color change. In all cases, the Arrhenius activation energy decreases alongside with decreasing chip moisture content. Blanching reduced acrylamide formation in potato chips in ∼64% (average value) in comparison with control chips at the three oil temperatures tested. For the two pre-treatments studied, average acrylamide content increased ∼58 times as the frying temperature increased from 120 to 180 °C. There was a linear correlation between acrylamide content of potato chips and their color represented by the redness component a¹ in the range of the temperatures studied.     

Feasibility of NIR interactance hyperspectral imaging for on-line measurement of crude composition in vacuum packed dry-cured ham slices

There is a growing market for packaged slices of dry-cured ham. The heterogeneity of the composition of slices between packages is an important drawback when aiming to offer consumers a product with a known and constant composition which fits individual consumer expectations. The aim of this work was to test the feasibility of NIR interactance imaging for on-line analysis of water, fat and salt and their spatial distribution in dry-cured ham slices. PLSR models for predicting water, fat and salt contents with NIR spectra were developed with a calibration set of samples (n = 82). The models were validated with an external validation set (n = 42). The predictive models were accurate enough for screening purposes. The errors of prediction were 1.34%, 1.36% and 0.71% for water, fat and salt, respectively. The spatial distribution of these components within the slice was also obtained.     

甘薯品种干率与油炸薯片含油量和硬度间的相关性

选择20个干率18.72%～35.02%的甘薯品种,切成1.6～1.8 mm薄片,(135±10)℃常压油炸,测定薯片含油量和硬度.结果表明薯片含油量与干率成线性负相关,相关系数R=-0.827,薯片硬度与干率成非线性正相关,相关系数R=0.965,薯片硬度与含油量呈非线性负相关性,相关系数R=-0.890.显示油炸薯片含油量和硬度不可能同时达到最佳值.干率24%～26%的品种,薯片含油量在25%左右,硬度值650～700 g,具有较好的油炸品质,可以考虑作为油炸薯片专用品种选育的主要方向.     

油炸马铃薯片中丙烯酰胺形成的影响因素的研究

丙烯酰胺是富含碳水化合物和氨基酸的食品经高温加热发生美拉德反应而产生的,但有关影响丙烯酰胺形成因素的研究却较少。探讨了油炸温度、原料中还原糖和氨基酸含量、鲜薯切片浸泡液的柠檬酸浓度、油炸前薯片的水分含量及抗氧化剂和油的使用时间对丙烯酰胺形成的影响。结果表明:原料中还原糖和氨基酸含量越高,产品中生成的丙烯酰胺就越多;油炸温度越高,产品中丙烯酰胺含量也相应越高;浸泡液柠檬酸浓度越大,产品中丙烯酰胺含量越低;而随着半成品中含水量的降低,产品中的丙烯酰胺含量也逐渐减少;在油中添加不同浓度的BHT和TBHQ以及采用使用时间不同的油,对加工出来的薯片之间丙烯酰胺含量没有显著的影响。     

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。     

Dielectric Properties of Potatoes and Potato Chips

SUMMARY— Dielectric properties (dielectric constant, ɛ'_r; loss tangent, tans; and dielectric loss factor, ɛ"_r) were determined for raw potatoes and for potato chips, using the precision slotted line technique. Measurements on raw potatoes were made at 77°F (25°C) and at frequencies of 300, 1,000, and 3,000 MHz (megahertz). Measurements on potato chips were made at three moisture levels; at 77°F (25°C), 125°F (51.6°C), and 180°F (82.2°0; and at frequencies of 300, 1,000, and 3,000 MHz. Moisture, total lipids, and nitrogen contents are reported for both the raw potatoes and the potato chips.
As would be expected from their high moisture content and the presence of various dissolved salts, the raw potatoes possess extremely high dielectric values.
Potato chips show a rapidly decreasing dielectric loss as moisture content is reduced; the loss values of the chips approach those of the oil used for frying them after moisture has been reduced to approximately 3% and the oil content has been increased accordingly.
For finish drying of potato chips, a frequency of 3,000 MHz will result in 3–4.5 times greater power production in the chips than will the use of a frequency of 1,000 MHz (in the moisture and temperature range at which the data were obtained). However, this difference in power production is due almost entirely to the difference in frequency since the difference in dielectric loss values at the two frequencies is quite small.     

On-line prediction of chemical composition of semi-frozen ground beef by non-invasive NIR spectroscopy

The chemical composition of industrial scale batches of frozen beef was measured on-line during grinding by near infrared (NIR) reflectance spectroscopy. The MM55E filter based non-contact NIR instrument was mounted at the outlet of a meat grinder, and the fat, moisture and protein contents determined from the average of each filter reading throughout the grinding of the batch. The filters were selected from full spectra measurements to be as insensitive to water crystallization as possible. For on-line calibration and prediction, 55 beef batches of 400–800 kg in the range of 7.66–22.91% fat, 59.36–71.48% moisture, and 17.04–20.76% protein, were ground through 4 or 13 mm hole plates. The regression results, presented as root mean square error of cross validation (RMSECV) were between 0.48 and 1.11% for fat, 0.43 and 0.97% for moisture and 0.41 and 0.47% for protein.     

Characterization of Thermal Properties of Potato Dry Matter–Water and Starch–Water Systems

ABSTRACT: Potato dry matter samples of varying moisture contents were analyzed by differential scanning calorimetry (DSC). One endothermic and one exothermic transition were observed when the moisture content was < 50% (w/w) in the dry matter–water system. Both endothermic and exothermic transitions of potato dry matter were influenced by moisture content. One endothermic transition at about 66 °C was observed when the samples were reheated after 2 wk of storage at 5 °C. Gelatinization and retrogradation of starch are chiefly responsible for the endothermic transitions in the potato dry matter. The exothermic transition may originate from chemical reactions such as Maillard and caramelization during heating of a potato dry matter–water system when water is limited (< 50%, w/w) and at temperatures > 120 °C     

茶多酚在油炸过程中对马铃薯片品质及其贮藏稳定性的影响

以感官品质、质构特性、理化特性、风味特性以及丙烯酰胺含量为指标,研究茶多酚在连续油炸过程中对马铃薯片品质的影响,并进一步探究茶多酚对马铃薯片贮藏稳定性的影响。结果表明,茶多酚对连续油炸过程中马铃薯片感官品质及硬度值的下降具有抑制作用;茶多酚对连续油炸过程中马铃薯片水分含量和含油率的增加具有明显的抑制作用,并且降低了薯片的含油率,茶多酚组T₂₄批次的马铃薯片含油率为41.96%±2.00%,显著低于空白组的46.29%±1.06%(P<0.05)。同时,与空白对照组相比,茶多酚抑制了马铃薯片劣变风味的产生,明显抑制了马铃薯片中有害物丙烯酰胺的生成。此外,茶多酚能够增加油炸马铃薯片的贮藏稳定性,平均货架期能够延长8 d。初步分析,茶多酚在油炸过程中对油脂品质的保护作用是其能够提高马铃薯片品质的重要原因。     

Determination of Antioxidant Activity and Polyphenols Content in Chips by Raman and IR Spectroscopy

The application of vibrational spectroscopy for the determination of total polyphenols content, antioxidant activity, colour parameters, and fat level in chips originated from yellow-, red- and purple-fleshed potato varieties is reported. Raman, infrared (IR) and near-infrared (NIR) spectra of the laboratory-prepared chips were collected. Combining spectral data with the results of reference analyses, partial least squares regression models were built. To characterise and compare the elaborated models, the relative standard errors of prediction were calculated for calibration and validation sets. In the case of total phenolics quantification by Raman/IR/NIR techniques, these errors (%) amounted to 4.0/7.0/7.1 and 6.4/8.5/8.4 for calibration and validation samples, respectively, whereas they were 4.9/7.7/4.8 and 6.6/8.3/6.8 for antioxidant activity. The obtained results demonstrate that both infrared and Raman spectroscopy can effectively replace commonly used extraction methods. It follows that Raman spectroscopy has the highest potential to be adopted for the online potato-derived product analysis.     

Acrylamide in Romanian food using HPLC-UV and a health risk assessment

The aim of this study was to investigate the level of acrylamide from coffee, potato chips and French fries in Romanian food. According to the European Food Safety Authority, coffee beans, potato chips and French fries have the highest levels of acrylamide. For this survey, 50 samples of coffee beans, 50 samples of potato chips and 25 samples of French fries were purchased from different producers from the Romanian market. Acrylamide levels have been quantified using high-performance liquid chromatography with a diode array detector (HPLC-DAD) method, using water as mobile phase. Health risk assessment was achieved by computing the average daily intake, hazard quotient, cumulative risk, carcinogenic risk and cancer risk. For coffee, potato chips and French fries, acrylamide was not shown to pose a health risk in Romanian food.     

水分、温度和检测光程对在线近红外光谱法测定结果的影响

为提高在线近红外(NIR)光谱仪在制丝线测定烟丝样品常规化学成分的准确度,在实验室模拟在线采集了烟丝样品不同含水率和温度条件下的近红外吸收光谱图,以及不同检测光程下同一个烟丝样品的近红外吸收光谱图,用数学模型预测了烟丝样品不同含水率、温度及不同检测光程下烟丝样品的烟碱和总糖值,并将预测值和化学实测值进行了对比分析.结果表明:①在实验范围内,随着烟丝样品含水率、温度的升高及检测光程的减小,在线NIR测定结果的相对误差有增大的趋势;②在线NIR光谱仪检测烟丝样品的最佳条件:含水率为12％～13％,温度为25～30℃,检测光程为16～20 cm.