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.     

On-line monitoring of fat,dry matter and acrylamide contents in potato chips using near infrared interactance and visual reflectance imaging

The contents of dry matter, oil and acrylamide are some of the most relevant parameters in the quality control of potato chips. Near infrared spectroscopy (NIR) is a common technique for routine analysis of bulk chemistry in different raw materials and products because it allows a fast and non-destructive analysis of samples. The objective of this research was to investigate the possibilities of using on-line NIR monitoring of acrylamide, moisture and oil content in potato chips. Sixty samples of potato chips from individual frying runs were measured on-line using a VIS/NIR interactance line scanner. The same samples were analysed in the laboratory to determine their corresponding moisture, acrylamide and oil contents. The mean VIS and NIR spectra for the 60 samples were modelled against the reference values for acrylamide, fat and dry matter using partial least squares regression (PLSR), and the regression models were validated using full cross-validation. On-line NIR interactance was found to predict fat and dry matter of potato chips with high accuracy, i.e. prediction errors of 0.99 and 0.86% (w/w), respectively. The corresponding correlations between predicted values and reference values were 0.99 and 0.97 for fat and dry matter. For acrylamide an average prediction error of 266 μg/kg was achieved using NIR and VIS signals in combination. The correlation between predicted values and reference values was 0.83 for this model. The system may be used to separate samples with very high acrylamide contents from samples with average to low contents.     

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。     

Deterioration of sunflower seed oil under simulated frying conditions and during small-scale frying of potato chips

The changes occurring in sunflower seed oil under simulated frying conditions and during potato chip frying were monitored. The changes monitored were in: (a) fatty acid composition, (b) triglyceride content, (c) octanoate content, (d) titratable acidity, and (e) colour. To simulate frying conditions either argon or air, with or without steam, was bubbled through the hot oil. For the frying of potato chips, two methods of frying were used, viz continuous frying throughout 1 day and intermittent frying over a total of 10 days. It was found that whenever the hot oil was exposed to air, whether during simulated frying or the frying of potato chips, there was evidence of oxidative deterioration. Steam appeared to have an antioxidant effect in the simulated frying experiments. In all experiments the molar yield of acidity was comparable in magnitude with that of the octanoate. The correlation of octanoate production with the losses of linoleate and triglyceride is discussed.     

Effect of Herbicides on Chemical Composition of Potato Tubers and Quality of the Subsequent Chips and Starch

Application of 6 different herbicides in potato cultivation resulted in changes of chemical composition of tubers, quality of chips and properties of starch. Sencor, Bladex, Topogard, Afalon and Aresin indicated rather unfavourable effects on chemical composition of the tubers. On one hand they increased the average weight of the tubers, on the other hand they decreased the dry matter (triazines) and starch content (Afalon). They increased the amount of reducing and total sugars (urea) and increased the content of amide nitrogen (triazines and Afalon) and amino acid nitrogen (Bladex). Sencor and Afalon resulted in darker colour of the chips. Afalon, Aresin and Chwastox increased the part of small granules or decreased the amount of large granules in the starch. Afalon and Bladex resulted in changes of phosphorus content, and Chwastox changed the amount of amylose in starch.     

The possibility of lowering oil content of potato chips by combining atmospheric frying with postfrying vacuum application

Four protocols involving the application of low pressures, either toward the end of frying or after frying, were investigated with the aim of lowering the oil content of potato chips. Protocol 1 involving frying at atmospheric pressure followed by a 3 min draining time constituted the control. Protocol 2 involved lowering of pressure to 13.33 kPa, 40 s before the end of frying, followed by draining for 3 min at the same pressure. Protocol 3 was the same as protocol 2, except that the pressure was lowered 3 s before the end of frying. Protocol 4 involved lowering the pressure to 13.33 kPa after the product was lifted from the oil and holding it at this value over the draining time of 3 min. Protocol 4 gave a product having the lowest oil content (37.12 g oil/100 g defatted dry matter), while protocol 2 gave the product with highest oil content (71.10 g oil/100 g defatted dry matter), followed by those obtained using protocols 1 and 3 (68.48 g oil/100 g defatted dry matter and 52.50 g oil/100 g defatted dry matter, respectively). Protocol 4 was further evaluated to study the effects of draining times and vacuum applied, and compared with the control. It was noted that over the modest range of pressures investigated, there was no significant effect of the vacuum applied on the oil content of the product. This study demonstrates that the oil content of potato chips can be lowered significantly by combining atmospheric frying with draining under vacuum.     

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。     

不同食用木薯品种（系）薯片加工适宜性研究

为了解不同食用木薯品种(系)炸薯片在品质上的差异,探讨其影响因子,筛选适宜加工薯片的木薯品种(系),以12个优良食用木薯品种(系)为材料进行炸片加工,对薯片进行感官评价及薯片含水率、质构等测定,并进行主成分分析和与鲜薯营养品质的相关分析。结果表明:NK-10感官评价值、内聚性和弹性值最高,SC9和M33硬度较大,咀嚼性差异不显著。相关性分析发现,木薯薯片感官组织状态、色泽与鲜薯支链淀粉含量分别呈显著相关(P<0.05)和极显著相关(P<0.01),相关系数分别为0.674、0.795。主成分分析获得了4个主成分,解析贡献率分别为34.325%、23.627%、16.900%、13.205%,品系NK-10综合评分最高,为0.875,其次是M9的0.565、ST的0.401。该研究表明木薯品种(系)NK-10、M9、ST适宜用于炸片加工。薯片口感、风味、含水率、咀嚼性、色泽和组织状态可作为其品质鉴定的重要指标,且木薯炸薯片的组织状态和色泽受到鲜薯支链淀粉含量的影响。     

Quality changes of edible oils during vacuum and atmospheric frying of potato chips

Demand for safe and nutritionally rich fried products is gaining a momentum among consumers, leading to the increased consumption of vacuum fried products. The impact of vacuum frying (VF)(110 °C, 40 kPa) on chemical composition of food, fatty acid profile, microstructure, oxidative stability and sensory attributes was assessed and differentiated with that of atmospheric frying(AF) (180 °C). The potato slices were fried in mustard and soyabean oil used repetitively for 25 h. The oil content of VF potato chips was lower (15.18%) than AF chips (18.98%), however water loss in AF chips was higher than VF chips by 1.63-fold. VF significantly prevented the PUFA degradation, minimizes transfatty acid (TFA) formation and maintain a low C18:2/C16:0 ratio as compared to AF. VF Chips fried in soyabean oil show an increase in TFA content from 2.15 to 2.63% and a decrease in PUFA from 51.57 to 45.16% as compared to AF chips where TFA content increased from 2.15 to 3.72% and PUFA shows a higher reduction from 51.57 to 37.69% at the end of 25 h of frying. This indicate that in AF, oil is safe for use upto 10 cycles of frying, while as in VF, the same oil can be used for upto 40 cycles of frying without quality deteoriation. Sensorial analysis revealed that VF chips retain a better colour, taste and flavour but were less crispy than that of AF chips. These findings validate the application of vacuum frying technology for the production of high-quality foods with lesser degradation of frying oil.Industrial relevanceFood manufacturers are now impelled by the health-conscious consumer base for the production of healthy food products. The toxic effect of foods fried in degraded oils on human health is now widely known and thus the production of safe fried foods is the need of hour globally. In this context, vacuum frying is the most feasible approach for the production of quality fried products retaining the natural colour, flavour, sensory and nutritional properties better than that of atmospheric frying. Vacuum frying causes the least degradation of fatty acid of the frying oil and the fried potatoes, producing healthy potato chips. Therefore, the oil used for vacuum frying have a greater shelf life and oxidative stability than atmospheric frying. However, the higher installation cost of vacuum fryer still limits its use in the street fried food market, where degradation of oil is more likely. Thus, for its widespread commercialisation in developing countries, steps should be taken both by government and manufacturing companies to reduce the installation costs.     

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。     

Fried sweetpotato user preferences identified in Nigeria and Ghana and implications for trait evaluation

Fried sweetpotato quality is important for variety adoption in West Africa. To inform breeding efforts, the study developed a product profile for sweetpotato chunk fries using mixed qualitative and quantitative methods. Root characteristics, processing attributes, in-mouth attributes and appearance of fried product were critical to final product quality. Raw roots should be hard, have smooth skin and no off-odours. Peeled roots should be hard to slice and not sticky. Stickiness and moist surface indicate high moisture content, associated with excessive oil absorption during frying. Hard to slice roots connote high dry matter. Fried product should be crisp, slightly sugary and mealy, have a uniform colour with brown tint and not be soggy. Crispness, mealiness and short frying time with limited oil absorption may be functions of starch. Understanding starch characteristics and other attributes that contribute to quality fried sweetpotato is critical for breeding sweetpotato genotypes with superior quality for frying.     

Studies on the usefulness of Cucurbita maxima for the production of ready-to-eat dried vegetable snacks with a high carotenoid content

Recent research indicates a beneficial influence of a diet rich in β-carotene on human health. For that reason, experiments were undertaken to process winter squash with a high carotenoid content into ready-to-eat dried snacks. Sensory quality and dietary value of chips and crispy cubes made from different cultivars were investigated.The suitability of winter squash for drying purposes depended mainly on the dry matter content in the raw material. Although all the investigated cultivars can be used for producing chips, obtaining high quality porous cubes requires at least 15% of dry matter. ‘Justynka F1’ emerged as the most suitable cultivar for processing; both chips and cubes produced from its fruits were characterized by a high sensory quality and contained significant amounts of beta-carotene (225- 253 μg g-1). Also, the cultivar ‘Amazonka’ could be considered for the production of chips as it allowed us to obtain a product with a high beta-carotene content (200 μg g-1) and good sensory properties. The dried ready-to-eat crispy vegetable snacks made from the new cultivars of winter squash could be exploited as a novel attractive product with the attractive taste and colour to serve as a valuable source of carotenoids in human diet.     

Amylose and amylopectin molecular fractions and chain length distribution of amylopectin in 12 varieties of Ghanaian sweet potato (Ipomoea batatas) flours

Sweet potato (Ipomoea batatas) is a commonly cultivated root crop in tropical and subtropical regions, including Ghana. Different varieties of sweet potato have been bred, in order to expand its utilisation within the food and industrial sector. This study analysed flours made from 12 recently developed Ghanaian sweet potato varieties in terms of their amylose and amylopectin molecular fractions and amylopectin chain length distribution. Starch content of the sweet potato flours ranged from 49 to 77 g/100 g dry matter, with 11 of the varieties containing above 60 g/100 g dry matter. An orange-fleshed variety, Apomuden, had the lowest amount of starch (48.9 g/100 g dry matter), while the cream-fleshed variety Histarch had the highest (77.3 g/100 g dry matter). The flours from the 12 sweet potato varieties had intermediate amounts of amylose, within the range 10–30 g/100 g dry matter, and showed typical molecular distribution according to size-exclusion chromatography (SEC). The fine structures of amylopectin, as revealed by anion-exchange chromatography, contained features common for starches of C-type X-ray pattern, but some structural differences were also observed.     

Tuber yield and quality characteristics of potatoes for off‐season crops in a Mediterranean environment

BACKGROUND: There is little research on evaluating the compatibility of potatoes for double cropping in southern Italy. The aim of this investigation was to assess tuber yield and some qualitative traits of tubers such as skin colour, tuber dry matter content and tuber nitrate content, both in winter–spring and in summer–autumn crops, as influenced by genotype and harvest time. RESULTS: Yield, skin colour and dry matter content of tubers were higher in the winter–spring crop than in the summer–autumn crop, attributable to the advantageous lag time in spring between solar radiation and temperatures and the disadvantageous lag in autumn. Spunta and Arinda performed well within each crop season, whereas Ninfa showed an important yield loss in autumn. In both off‐season crops, delaying tuber harvest until leaf senescence increased yield and improved quality attributes such as tuber dry matter content and skin colour, whereas nitrate contents significantly decreased in the winter–spring crop and increased in the summer–autumn crop. Ninfa showed less tendency than Arinda and Spunta to accumulate nitrate in tubers in both off‐season crops. CONCLUSION: It might be advantageous to examine in further research which mechanisms sustain compatibility to the autumn and assess other quality characteristics for the fresh market in the contrasting climatic conditions of the two off‐season crops. Copyright © 2009 Society of Chemical Industry     

复合马铃薯片油炸工艺研究

以马铃薯淀粉和马铃薯全粉为主要原料,对复合马铃薯片的油炸工艺参数进行了研究。采用正交试验,确定了生产低含油量、低丙烯酰胺(AA)含量、高脆度复合薯片的最佳油炸工艺参数,即油炸前坯料的含水量控制在20%左右,含盐量2%左右,油温以160℃为佳,炸制时间为40 s,油炸薯片丙烯酰胺含量为0.28 mg/kg,在市售薯片基础上降低26.32%;含油量为23.36%,降低了1.47个百分点。     

Optimisation of processing variables in the preparation of sweet potato chips using response surface methodology

Models capable of predicting the product quality of sweet potato chips have been developed using response surface methodology and used to determine the optimum processing conditions. Moisture loss, oil uptake, crispness (measured using a bending-snapping test in the TA.XT2 Texture Analyser), and sensory attributes such as colour, flavour, and texture were used to assess the product quality in the preparation of sweet potato chips. The optimum conditions which were attained for maximum moisture loss (11.65% on wet basis), minimum oil uptake (2.57%), crispness (794.37 g), colour score (7), flavour score (7) and texture score (7) were: frying temperature, 174.7 °C; salt concentration, 0.45%; citric acid concentration, 0.37%; potassium metabisulphite concentration, 0.65%; and frying time, 26 s.     

Technological evaluation of new cultivars for potato chips manufacturing

Potato tubers of cvs. Condor, Diamont, Baraka, Mondial and Draga were used to produce chips of 1.0 mm slice thickness using an industrial slicer. Half of the slices quantity was immediately blanched in water at 100°C for approximately 5 min. Frying was carried out at 165–170°C in cotton seed oil. Both cvs. Diamont and Condor were the best varieties in the nutritional composition, since they contained the highest content of total solids (24.2 and 22.8%), crude protein (10.9 and 10.2%), total free amino acids (270 and 246 μmol/g DM), ascorbic acid (1.5 and 1.4 mg/100 g DM) and digested protein (49.8 and 49.6% for pepsin enzyme as well as 76.0 and 78.3% for trypsin enzyme). In contrast, they contained the lowest level of reducing sugars i.e. 0.8 and 0.9%, respectively. The same both varieties produced the maximum final yield of chips from both unblanched and blanched slices (50.0 and 47.4% as well as 48.9 and 45.8%, respectively) with the lowest final oil content i.e. <42%. Slightly differences in the final moisture content of chips were noticed. Blanching before frying led to a decrease in the final oil content of chips produced from all potato varieties. Sensory evaluation of the produced chips revealed that the favourable chips with the best quality attributes i.e. lighter and uniform in colour, lower final oil content, natural odour, more crisp and better in taste can be produced by using slices from cvs. Condor and Diamont. Furthermore, blanching before frying reduced significantly the oil content of chips and improved both colour and texture (more crispness) of the produced chips.     

Vacuum frying as a route to produce novel snacks with desired quality attributes according to new health trends

Consumers look for products that contribute to their wellness and health, however, even health-conscious consumers are not willing to sacrifice organoleptic properties, and intense full-flavor snacks remain an important trend. The objective of this study was to examine most important quality parameters of vacuum (1.92 inHg) and atmospheric-fried carrot, potato, and apple slices to determine specific advantages of vacuum technology. Slices were fried using equivalent thermal driving forces, maintaining a constant difference between oil temperature and the boiling point of water at the working pressure (ΔT = 60 and 80 °C). This resulted in frying temperatures of 160 and 180 °C, and 98 and 118 °C, for atmospheric and vacuum frying, respectively. Vacuum-fried carrot and potato chips absorbed about 50% less oil than atmospheric-fried chips, whereas vacuum-fried apple chips reduced oil absorption by 25%. Total carotenoids and ascorbic acid (AA) were greatly preserved during vacuum frying. Carrot chips vacuum fried at 98 °C retained about 90% of total carotenoids, whereas potato and apple slices vacuum fried at 98 °C, preserved around 95% of their initial AA content. Interestingly, results showed that the antioxidant capacity of chips may be related to both the presence of natural antioxidants and brown pigments developed at elevated temperatures. PRACTICAL APPLICATION: A way to reduce detrimental effects of deep-fat frying is through operating-pressure reduction, the essence behind vacuum deep-fat frying. In this way, it is possible to remove product moisture at a low temperature in a low-oxygen environment. The objective of this research was to study the effect of oil temperature reduction when vacuum frying traditional (potatoes) and nontraditional products (carrots and apples) on most important quality attributes (vitamins, color, and oil uptake). Results are promising and show that vacuum frying can be an alternative to produce nutritious and novel snacks with desired quality attributes, since vitamins and color were greatly preserved and oil absorption could be substantially reduced.     

Quality evaluation of processing potatoes by near infrared reflectance

The percentage dry matter and reducing sugar content are prime quality parameters for assessing the potential of potato tubers to produce acceptable yields of processed products possessing good textural and colour quality attributes. A study was conducted to develop a near infrared (NIR) calibration for dry matter which would be unaffected by storage time and crop year, and to assess whether NIR could be used to screen tubers with high reducing sugar content from tubers with more acceptable levels. Tubers from commercial growers of French fry processing potatoes were sampled over two years for dry matter and one year for sugars. Tubers used for development of the NIR calibration were stored at 8°C, while those for sugars were stored at 8, 5 and 2°C. A small coin of potato flesh was excised from each tuber, its NIR spectrum obtained on a scanning spectrophotometer and its specific gravity and dry matter, or its reducing sugar content, determined. Correlation plots indicated that wavelengths that correlated well for specific gravity correlated well for dry matter. The standard error of performance for NIR determination of percentage dry matter varied from 1.3 to 1.5%. Calibrations for dry matter were robust and were not affected by time or conditions of storage nor by changeover from one crop year to another. It appears, however, that adjustments to the NIR calibration would be required at harvest time. Coefficients of variation (CV) in determining dry matter by NIR were 5–6%. Spectral averaging appears to have potential for improving on this CV. NIR in reflectance mode was unable to act as a screening tool for unacceptable sugar content in tubers. © 1999 Society of Chemical Industry     

Physico‐chemical and sensory attributes in conjunction with multivariate analysis of two potato (Solanum tuberosum L.) cultivars after 90 days of storage: an exploratory authentication study

Two cultivars of potato (Spunta and Agria), were studied in terms of their physico‐chemical and sensory characteristics. These cultivars were cultivated in three geographical regions of Greece (Macedonia, North Greece; Thessaly, Central Greece; Peloponnese, South Greece) and were stored for 90 days after harvesting. The physico‐chemical characteristics of the tubers determined, were pH, total acidity, firmness, dry matter and content in Ν, in Κ, P, Cu, Mn, Zn and Fe. The sensory characteristics measured for raw tubers of potato after storage, were skin colour, skin brightness, internal colour, surface roughness, odour intensity, moistness, surface wrinkling and stains while the sensory characteristics measured for the boiled tubers of potato were odour intensity, moistness, special taste, sweet taste, aftertaste persistence, metal taste, pastiness, mastication, flavour intensity, elasticity and overall acceptability. The application of multivariate analysis (principal component analysis, cluster analysis and discriminant analysis), revealed a variety of relations between the various parameters and resulted in satisfactory grouping either per geographical region or per cultivar.