Reduction of acrylamide formation in potato slices during frying

Reduction of acrylamide formation in potato chips was investigated in relation to frying temperature and three treatments before frying. Potato slices (Tivoli variety, diameter: 37 mm, width: 2.2 mm) were fried at 150°C, 170°C and 190°C until reaching moisture contents of ∼1.7 g water/100 g (total basis). Prior to frying, potato slices were treated in one of the following ways: (i) soaked in distilled water for 0 min (control), 40 min and 90 min; (ii) blanched in hot water at six different time-temperature combinations (50°C for 30 and 70 min; 70°C for 8 and 40 min; 90°C for 2 and 9 min); (iii) immersed in citric acid solutions of different concentrations (10 and 20 g/l) for half an hour. Glucose and asparagine concentration was determined in potato slices before frying, whereas acrylamide content was determined in the resultant fried potato chips. Glucose content decreased in ∼32% in potato slices soaked 90 min in distilled water. Soaked slices showed on average a reduction of acrylamide formation of 27%, 38% and 20% at 150°C, 170°C and 190°C, respectively, when they were compared against the control. Blanching reduced on average 76% and 68% of the glucose and asparagine content compared to the control. Potato slices blanched at 50°C for 70 min surprisingly had a very low acrylamide content (28 μm/kg) even when they were fried at 190°C. Potato immersion in citric acid solutions of 10 and 20 g/l reduced acrylamide formation by almost 70% for slices fried at 150°C. For the three pre-treatments studied, acrylamide formation increased dramatically as the frying temperature increased from 150°C to 190°C.     

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。     

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.     

Activities of hydrocolloids as inhibitors of acrylamide formation in model systems and fried potato strips

Effects of eight hydrocolloids on acrylamide (AA) formation were compared. At 2% (w/w), pectin, alginic acid (>50% reduction) and xanthan gum (∼20%) significantly (P < 0.05) reduced acrylamide formation in chemical models. In the fried snack model, effective inhibition of acrylamide formation (∼30%) by most of the hydrocolloids was observed only when the concentration was increased to 5%. Immersing potato strips for 1 h in a 1% alginic acid solution before frying produced inhibition of acrylamide formation similar to that in a 5% solution, and immersing for 5 h led to a significantly lower AA content (∼60% versus ∼30% reduction) compared with immersing for 1 h in a 1% or 5% immersion solution. Similar phenomena were also observed for pectin. The findings suggest alginic acid and pectin are promising inhibitors of acrylamide formation, and immersion time is an important determinant for their effects against acrylamide formation in fried potato products.     

Reduction of acrylamide formation by selected agents in fried potato crisps on industrial scale

Great interest and rapid research efforts on acrylamide in foods followed an announcement in April 2002 by the Swedish National Food Authority and the University of Stockholm. Reduction of acrylamide in high-temperature processing foods, including selection of the raw material and variation of processing parameters, etc. were extensive reported. In this research, effect of some agents on acrylamide formation was investigated. A glucose-asparagines reaction model system was used to test the effect of ferulic acid, catechin, CaCl₂, NaHSO₃, and l-cysteine on inhibition of acrylamide formation and three efficient inhibitors, NaHSO₃, CaCl₂ and l-cysteine were screened. The results showed that immersing of the fresh potato chips using different concentration of the agents greatly inhibited acrylamide formation in fried potato crisps, and the efficiency increased as their concentrations increased; among them, l-cysteine is the most efficient agent but CaCl₂ is most potential. Effects of these food additives on the texture of fried potato crisps were also studied. It was found that l-cysteine showed little effect on the texture of the crisps and CaCl₂ is regarded as the suitable choice because of its low price and the acceptable mouth feel of fried crisps treated by CaCl₂, although it increased the brittleness. Moreover, the application of CaCl₂ in industrial production of fried potato crisps was also studied. In the blanching process (deactivation process of enzymes at 85 °C), a computerized electrical conductivity detector was used to keep the concentration of CaCl₂ at constant and the result showed that immersion of potato slices in CaCl₂ solution at 5 g/L reduced acrylamide formation by more than 85% in fried crisps.Industrial relevanceThis research presents a technology to inhibit acrylamide formation in fried potato chips by immersion of fresh potato chips with some food additives. The approach suggested that cysteine and calcium chloride significantly decreased the content of acrylamide in fried potato chips and their concentrations could be kept constant by using a conductor as a detector.     

Oil uptake and texture development in fried potato slices

The objective of this work was to study oil absorption and the kinetics of texture development of fried potato slices during frying. 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 texture and oil content were measured periodically. Oil uptake was higher in 15% for blanched samples than for control samples after 20 s of frying. Besides, the higher the frying temperature, the lower the oil absorption in control samples. Textural changes in fried potato slices were followed by the parameter maximum force (MF) extracted from the force vs. distance curves corresponding to different sampling times. Normalized maximum force (MF*) was used in modeling textural changes in the potato slices during frying in both the initial tissue softening process and the later crust development process. Higher temperatures accelerated these processes; however neither the temperature nor the pre-treatment had a significant effect (P > 0.05) over the final texture of the fried potato chips.     

A methodology for evaluating the formation and human exposure to acrylamide through fried potato crisps

Potato crisps are a popular snack food which have been implicated as a potential source of acrylamide. This study develops a farm-to-fork human exposure assessment model for acrylamide in fried potato crisps for Irish consumers. The model used Monte Carlo simulation techniques to model the various stages from on farm production of potatoes, storage, processing, crisp production and final human consumption of potato crisps. A baseline model is created and a number of scenarios are subsequently created to look at the impact of different model assumptions and input parameters. The baseline model found that the mean level of acrylamide in potato crisps in Ireland was 720 μg/kg. Irish consumer exposure to acrylamide in potato crisps was estimated to be 0.052 and 0.064 μg/kg bw/day for males and females, respectively. A sensitivity analysis revealed the important parameters influencing the model predictions. The initial level of reducing sugars was found to be the most important parameter (correlation coefficient 0.58 and 0.57 for glucose and fructose, respectively), highlighting the importance of selecting cultivars with low reducing sugar levels for crisp production. The cooking regime had a significant impact on model predictions, highlighting the need for further research into the impact of different time and temperature combinations. Blanching and soaking of potatoes were also identified as important risk reduction processes.     

Influence of variety and processing conditions on acrylamide levels in fried potato crisps

An investigation was carried out to determine the factors of greatest significance for the level of acrylamide formation in fried potato crisps. Factors under investigation were potato variety, the inclusion of a water soak prior to frying, cooking oil type, cooking temperature and cooking time. Data showed that cooking time and temperature had the greatest influence on acrylamide formation. Cooking oil type and soaking were found to be insignificant. Potato variety had a significant effect, with acrylamide levels found to be controlled by the levels of reducing sugars rather than asparagine. In addition, there were indications that the condition of the cooking oil (as indicated by peroxide value) did not affect acrylamide levels.     

Enzymatic mitigation of acrylamide in fried potato chips using asparaginase from Aspergillus terreus

Acrylamide in foods is declared as carcinogen. In the present work, the effect of enzymatic pretreatment and other parameters like enzyme concentration, frying conditions with respect to temperature and time, size of potato chips, and effect of sodium chloride and citric acid on mitigation of acrylamide were studied. The concentration of acrylamide in fried potatoes after the pretreatment was found to be 815.63 μg kg^?1. The optimised asparaginase concentration for the mitigation of acrylamide was calibrated as 4 U mL^?1, and optimised frying time and temperature were 15 min and 170 °C, respectively. An in‐depth kinetic relationship for the effect of asparaginase on the mitigation of acrylamide was studied. The prime novelty of the project is focused on the immobilisation of asparaginase to nanomagnetic particles for redundant usage with stabilised enzyme activity. The work projected three stables cycles of asparaginase activity and on further usage of the immobilised enzyme resulted in decreased activity. The repeated use of immobilised asparaginase provides the advantage of decreasing cost in processing.     

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。     

Tuber components affecting acrylamide formation and colour in fried potato: variation by variety,year, storage temperature and storage time

Variation in asparagine and glucose contents, identified as precursors for acrylamide development in model experiments, has been studied in eight potato clones during long‐term storage at 3 and 10 °C. In addition, glutamine, fructose and sucrose contents were determined and the role of all five substances in colour formation in fried potato products was assessed. Large genotype differences were found in all characteristics, and the ranking order was almost the same for different years and storage times. Breeding for potatoes with low asparagine levels as well as low reducing sugar levels might be another way, in addition to altering processing parameters, to keep the acrylamide level low in fried products. Storage per se at low temperature did not result in higher asparagine levels. The risk that elevated reducing sugar levels during low‐temperature storage might lead to increased acrylamide levels needs further investigation. The determined tuber components accounted for only 11–60 per cent of the total variation in fry colour after storage at 3 °C. It is suggested that screening based on crisp colour in November, perhaps complemented with a few later controls on interesting clones, could be useful for sorting out clones with good crisping abilities during the rest of the low‐temperature storage season. Copyright © 2004 Society of Chemical Industry     

抑制鲜切油炸薯片中丙烯酰胺产生的在线控制研究

前期研究表明,半胱氨酸、CaCl2等离子型物质能有效抑制油炸薯片中丙烯酰胺的产生。但在浸泡过程中其浓度会不断降低,因此如何在线监控抑制剂浓度并及时补充成为抑制剂能否成功用于工业化生产的关键。根据抑制剂浓度与电导率之间的线性关系,采用电导率仪监控浸泡液中抑制剂浓度,通过电导率仪获得的数据实时补充抑制剂。     

Effect of natural extracts on the formation of acrylamide in fried potatoes

The objective of the present work was to evaluate the effect of natural extracts on the formation of acrylamide in fried potatoes. The aqueous extracts used were obtained from wild oregano (Origanum vulgare), thyme (Thymus vulgaris), cinnamon (Cinnamomum verum), bougainvillea (Bougainvillea spp) and green tea (Camellia sinensis), which presented a high percentage of free radical inhibition (DPPH) (48–99%) and content of total phenolic compounds (205–547 μg EAG/μg of d.w.). Potatoes were submerged in the antioxidant extracts at a concentration of 1 g/L for 1 min, before being fried and their acrylamide concentration quantified by GC–MS. The extracts from green tea, cinnamon and oregano reduced the acrylamide level by 62%, 39% and 17%, respectively. The potatoes submerged in cinnamon and bougainvillea extracts showed differences in the color parameters compared to the control potatoes (P < 0.05); however, no significant differences (P > 0.05) were found in the texture and the peroxide values. The sensorial evaluation showed that the acceptance of the potatoes was not affected by the treatment applied. Thus, we can conclude that pre-treating potatoes with antioxidants before frying produces beneficial effects such as a reduction in acrylamide content, without any significant changes in their physicochemical, sensorial and textural properties.     

复合抗氧化剂对油炸鲜切薯片中丙烯酰胺和氯丙醇酯的抑制作用

目的 研究由植酸和鼠尾草酸组成的复合抗氧化剂对油炸鲜切薯片中丙烯酰胺和氯丙醇酯的抑制作用。方法 通过测定酸价(acid value, AV)和过氧化值(peroxide value, POV)对不同浓度植酸和鼠尾草酸进行评估, 并利用响应面优化实验确定复合抗氧化剂的最优配比。同时以油炸鲜切薯片为研究对象, 评价复合抗氧化剂对薯片和油脂中丙烯酰胺、氯丙醇酯及其品质的影响。结果 在180℃ 30 min下, 植酸抗氧化最佳浓度为0.16 g/kg, 鼠尾草酸最佳浓度是0.4 g/kg。根据响应面优化法设计实验并通过数据方差分析和响应面图可得: 在植酸浓度0.06 g/kg, 鼠尾草酸浓度0.2 g/kg时, AV和POV达到最低, 油脂抗氧化效果最好。复合抗氧化剂对丙烯酰胺的抑制率最高可达80.5%, 对氯丙醇酯有一定的抑制作用, 其中对3-氯-1,2-丙二醇酯抑制率最高达到49.2%。结论 复合抗氧化剂在提高棕榈油煎炸稳定性、抑制丙烯酰胺和氯丙醇酯产生方面表现出较好的优势, 能有效延缓煎炸油品质恶化, 并且对煎炸油和薯片品质有一定的保护作用。     

Oil partitioning between surface and structure of deep-fat fried potato slices: A kinetic study

The present work deals with the kinetics of partitioning of oil on the surface as well as in the structure during holding of fried potato slices at elevated temperatures (100, 120, 140, 160 and 180 °C) compared with controls. After frying, the oil present on the surface migrates into structure due to condensation of vapor inside the product resulting in the creation of a vacuum. However, the oil present on the surface need not migrate into the structure, if the fried product is held at elevated temperatures. Further, the excess oil, which did not migrate into structure, can be removed by absorbent paper. The oil partition coefficient, defined as the ratio of oil present on the surface to the structure, during holding of samples at 180 °C was found to be 3.06, whereas the oil partition coefficient of the sample held at ambient temperature was 0.53, which indicates the availability of oil on the surface of fried product held at elevated temperature. The mass transfer coefficient of oil corroborated with the above finding. The holding of deep-fat fried product at 180 °C followed by the removal of oil from the surface using high absorbent paper reduced the oil content of the final product from 0.440 to 0.332 kg of oil/kg dry solids.     

An experimental set-up for studying acrylamide formation in potato crisps

The objective of this work was to set up lab-scale equipment for production of crisps mimicking industrial conditions. Slices of Saturna potatoes were deep-fat fried for 2-4.5 min at 160 °C. A solid phase extraction method for acrylamide from potato crisps was used, and the extraction recovery was calculated to 95%. Acrylamide was analysed using liquid chromatography tandem mass spectrometry. The relative standard deviation was below 3% for analyses performed on the same day and below 5% for inter-day analyses. The limit of quantification was estimated to be 160 μg/kg potato crisps. The colour of potato slices was determined using a digital imaging method and related to the acrylamide content. There were tendencies that L*(lightness) decreased and that that a*(redness) and b*(yellowness) increased with increasing acrylamide content. In another experiment, potatoes with different glucose levels were fried for 4 min but no significant difference in acrylamide content (2200-2800 μg/kg) was observed. The experiment was repeated after three months of storage. The levels of acrylamide increased significantly to 8200-13200 μg/kg. The potatoes had been fertilized with different levels of nitrogen, but no relation was found between the nitrogen supplied and the acrylamide content. The experimental set-up was shown to give realistic and reproducible experimental data, regarding colour, water content and acrylamide levels. It will be used together with the analytical methods as a platform for further research on the formation of acrylamide.     

油炸马铃薯片中丙烯酰胺形成的协同阻断研究

目的研究油炸温度、油炸时间对马铃薯片中丙烯酰胺生成的影响,进而探讨半胱氨酸(Cys)和热烫处理对丙烯酰胺生成的协同阻断作用。方法将试样马铃薯片分别在不同浓度的Cys(0~5 g/L)溶液中,进行热烫(25~85℃)前处理,在不同温度(140~220℃)以及油炸时间(0~35 min)条件下,油炸处理,利用衍生化气相色谱-质谱联用(GC-MS)法测定样品中的丙烯酰胺含量。结果无预处理下,油炸马铃薯片中丙烯酰胺的生成量,随油炸时间或油炸温度的增加,呈先升高后降低的变化趋势,油炸温度为180℃的条件下,油炸3 min时,达到最大值5.16 mg/kg;油炸时间为5 min的条件下,油炸温度为200℃时,达到最大值4.85 mg/kg。热烫前处理对丙烯酰胺生成具有显著抑制效果,抑制率随热烫温度的升高而增大,室温条件下Cys溶液浸泡对丙烯酰胺生成具有抑制效果,抑制率随Cys浓度增加未见明显变化,然而温度升高后,出现协同阻断效应,Cys浓度为5 g/L和热烫温度为85℃的条件下,丙烯酰胺抑制率达100%。结论 Cys和热烫处理对抑制丙烯酰胺的生成存在协同阻断效应,协同作用下的抑制率与两者单独作用相比显著增加。     

油炸食品中丙烯酰胺分析方法研究进展

对食品中丙烯酰胺分析方法的研究进展进行了综述。主要包括GC-MS、LC-MS和LC-MS-MS方法分析食品中的丙烯酰胺以及一些国家机构规定的官方分析方法。另外,对现有分析方法的优缺点进行了评述,对食品中丙烯酰胺的分析方法进行了展望。     

油炸食品中丙烯酰胺的形成及减少措施

食品在加工过程中,特别是富含天门冬氨酸和还原糖的物质在高温(120℃以上)加工过程中会产生丙烯酰胺.试验表明,丙烯酰胺对动物有致癌性、神经毒性、生殖发育毒性的作用,但还没有足够的证据表明,食品加工过程中产生的丙烯酰胺对人体有致癌性.然而丙烯酰胺作为食品加工过程中产生的不受欢迎的物质,仍应尽量减少摄入.丙烯酰胺主要存在于油炸、高温烘焙的食品中,减少油炸食品中丙烯酰胺含量的途径主要有:减少或消除形成丙烯酰胺的前体物质;抑制加工过程丙烯酰胺的生成;破坏或使食物中形成的丙烯酰胺重新反应;在食品消费前将形成的丙烯酰胺去除.同时,改变以油炸和高脂肪食品为主的饮食习惯,尽量减少或防止丙烯酰胺可能对人体造成的伤害.