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.     

Acrylamide in potato crisp—the effect of raw material and processing

Reducing sugars and free amino acids were analysed in slices from three potato cultivars before and after blanching (0-3 min). The potato crisps were deep fried at 185 °C for different times (3-8.5 min), and analysed for the concentration of acrylamide (AA) and moisture. Potato cultivar and the temperature during processing were important parameters for AA formation in potato crisps. The amount increased with an increase in the processing time. Blanching before deep-frying reduced the concentration of free asparagine and reducing sugar in the raw material. We found no effect of blanching as pretreatment on the concentration of AA in the potato crisps. Any relationship was not detected between the levels of asparagine in the different cultivars, before and after blanching, and the formation of AA in the crisp products. However, it was shown that the content of reducing sugars determined the level of AA after frying.     

Variety and storage conditions affect the precursor content and amount of acrylamide in potato crisps

BACKGROUND: Acrylamide, a probable human carcinogen, is formed from the amino acid asparagine and reducing sugars when potato products are processed at high temperatures. This is a two‐year study on five Swedish‐grown potato clones, two of which are adapted to cold storage. The clones represented a wide range of precursor concentrations: asparagine, 3.7–15.3 mg g^?1; reducing sugars, 0.9–14.9 mg g^?1. Crisps were prepared in laboratory‐scale equipment mimicking industrial processing conditions. RESULTS: Potatoes stored at 4 °C had significantly higher levels of glucose and fructose than potatoes stored at 8 °C. Acrylamide levels were significantly higher in crisps made from potatoes stored at 4 °C. Two clones with a large difference in asparagine concentration but similar glucose and fructose concentrations gave crisps with significantly different acrylamide contents. The lowest levels of acrylamide were found in crisps made from the potato variety with the lowest asparagine concentration. CONCLUSION: The findings show that variety and storage conditions influence the levels of precursors. Acrylamide formation in crisps can be reduced by using potato varieties with low levels of both asparagine and reducing sugars. Mass transport of precursors during heating is suggested to be important for acrylamide formation in potato crisps. Copyright © 2007 Society of Chemical Industry     

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。     

Kinetic modelling: A tool to predict the formation of acrylamide in potato crisps

Three empirical models were used to fit the formation of acrylamide in crisps of three different cold-sweetened potato genotypes, fried under the same experimental conditions. Statistical methods were used to compare the performance of the models, with the “Logistic-Exponential” model performing the best. The obtained model parameters for the formation of acrylamide showed improvement in precision compared to an earlier study, the precision of the parameter estimates for the degradation of acrylamide was still problematic. Nevertheless, the predictive capacity of the “Logistic-Exponential” model was tested, as this model showed a strong correlation between parameter a and the reducing sugar content of the raw potato. The predictions from this model for the formation of acrylamide in potato crisps were close to earlier reported experimental values. Therefore, the use of the “Logistic-Exponential” model as a tool to predict acrylamide in potato crisps seems promising and should be developed further.     

Important factors to consider for acrylamide mitigation in potato crisps using pulsed electric fields

This preliminary study aimed to compare the application of pulsed electric field (PEF) with a traditional blanching as pre-treatments before frying for the mitigation of acrylamide content in potato crisps.Measuring the degree of cell disintegration index (p_o) and the changes in water electrical conductivity during washing of potato slices, PEF protocol and sample preparation scheme were optimized. Peeled potato slices (thickness 1.5 ± 0.2 mm) were subjected to PEF (1.5 kV/cm, pulse duration 10 μs, total treatment time 10 ms, pulse frequency 100 Hz) and to blanching (85 °C for 3.5 min) pre-treatments and then to washing in water, evaluating the reduction of acrylamide precursors (reducing sugars and free asparagine). After frying (175 °C, 3 min), product quality, in terms of colour, texture and acrylamide content were evaluated. Results showed that PEF promoted acrylamide precursors leaching followed by a reduction of the final acrylamide content of around 30%, significantly higher if compared to the reduction obtained with blanching, with only slight modifications of the final quality of the product, in terms of colour and texture.Industrial relevanceThe Commission Regulation (EU) 2017/2158 of 20 November 2017 has introduced new benchmark levels and mitigation strategies for the reduction of the presence of acrylamide in foods, directing food businesses to the research of measures to lower the acrylamide formation in foods. The actual industrial production process of fried potato crisps involves the use of many mitigation strategies, such as a blanching of raw potatoes. However, the traditional blanching treatment presents several practical drawbacks and leads to undesirable changes of the product quality. The application of PEF as a pre-treatment could reduce the acrylamide content in deep-fat fried potato crisps. This preliminary study gives important indications regarding the possibility of combining a PEF pre-treatment on raw potato slices with subsequent industrial processing steps for the production of potato crisps with low acrylamide concentration.     

Dietary exposure to acrylamide from potato crisps to the Spanish population

Potato crisps are one of the food commodities that contribute most to overall dietary human exposure of acrylamide. This investigation has estimated the dietary exposure to acrylamide form potato crisps in the Spanish population. Sampling of potato crisps (n = 36) from 16 different producers were carried out in March 2008. An average level of 740 µg kg^?1 (ranging from 81 to 2622 µg kg^?1; minimum to maximum) and a median of 592 µg kg^?1 were obtained. Acrylamide levels in marketed potato crisps have been significantly reduced (nearly to 50%) compared with a previous sampling performed 4 years earlier. The observed signal value (90th percentile) was 1377 µg kg^?1 with 86% of the samples with acrylamide levels lower than 1000 µg kg^?1. Dietary exposure to acrylamide from potato crisp consumption in the total Spanish population was estimated to be 0.042 µg kg^?1 body weight day^?1 by using a deterministic approach based on the National consumption database. In a second study, dietary exposure (based on a 3-day food record) was determined to be 0.053 µg kg^?1 body weight day^?1 for the adult population (17–60 years) and 0.142 µg kg^?1 body weight day^?1 for children (7–12 years). The contribution of potato crisps to the estimated dietary acrylamide exposure of the Spanish population is moderate as compared with other European Member States.     

How much reducing sugar may potatoes contain to avoid excessive acrylamide formation during roasting and baking?

For many consumers, potatoes fried or roasted in professional or private kitchens are the most important source of exposure to acrylamide. Acrylamide formation can be reduced by appropriate preparation techniques, but suitable potatoes are a prerequisite. The tendency of potato to form acrylamide can be approximated by the content of reducing sugar. Roast potatoes (hash browns, Rösti) and oven-fried potatoes (Bratkartoffeln) were prepared to optimum culinary quality regarding crispiness and then evaluated in terms of browning, roasting flavor and acrylamide content. Preparation procedures were optimized to produce a minimum of acrylamide. It is concluded that potatoes with less than 0.2 g/kg fresh weight fructose and glucose are not suitable for roasting (insufficient browning and flavor), while roasted products of minimum crispiness prepared from potatoes with more than 1 g/kg reducing sugar contain more than 500 µg/kg acrylamide. It is proposed that potatoes which may be used for roasting and frying should contain less than 1 g/kg fresh weight of reducing sugar. This can easily be fulfilled with the most important potato cultivars grown in Switzerland, but presupposes that potatoes are no longer stored at 4 °C.     

The effect of asparaginase on acrylamide formation in French fries

Acrylamide formation in French fries was investigated in relation to blanching and asparaginase soaking treatments before final frying. Par-fried potatoes of Bintje variety were prepared by cutting strips (0.8 × 0.8 × 5 cm) which were blanched at 75 °C for 10 min. Unblanched strips were used as the control. Control or blanched strips were then dried at 85 °C for 10 min and immediately partially fried at 175 °C for 1 min. Finally, frozen par-fried potatoes were fried at 175 °C for 3 min to obtain French fries. Pre-drying of raw or blanched potato strips did not generate acrylamide formation as expected. Partial frying of pre-dried control potato strips generated 370 μg/kg of acrylamide and the final frying determined French fries with 2075 μg/kg of acrylamide. When control potato strips were treated with a 10000 ASNU/l asparaginase solution at 40 °C for 20 min, the acrylamide formation in French fries was reduced by 30%. When blanched potato strips were treated in the same way, the produced French fries have 60% less acrylamide content than blanched strips without the enzyme treatment. Soaking of blanched potato strips (75 °C, 10 min) in an 10000 ASNU/l asparaginase solution at 40 °C for 20 min is an effective way to reduce acrylamide formation after frying by reducing the amount of one of its important precursors such as asparagine.     

3种添加剂对油炸薯片丙烯酰胺产生和质构的影响

在前期研究基础上,探讨了3种添加剂NaHSO3、CaCl2和半胱氨酸浸泡土豆片对油炸薯片中丙烯酰胺形成的抑制作用,同时采用白度仪和质构仪测定了油炸薯片的白度和脆度,发现半胱氨酸和CaCl2能有效地抑制丙烯酰胺形成且对薯片色泽和脆度影响较小,是两种具有应用前景的丙烯酰胺抑制剂。     

Optimization of the blanching process to reduce acrylamide in fried potatoes

A central composite design was used to study the effect of blanching time and temperature on the extraction of reducing sugars from potato strips and slices. After frying, the impact of both factors on the acrylamide content in French fries and potato crisps was evaluated. Acrylamide could be lowered more efficiently in potato crisps compared to French fries, due to a more pronounced extraction of sugars from potato slices upon blanching. In both products, blanching temperature was the main influencing factor for sugar extraction and subsequent acrylamide mitigation. Blanching at temperatures of about 70 °C for a short period of time (about 10 min) was more efficient compared to blanching at lower temperatures, which appeared more time-consuming. However, the extraction efficiency of reducing sugars was over 10% lower when the potato cuts were blanched in water which was previously used for blanching, leading to over 10% less reduction in the final acrylamide content.     

Acrylamide levels in potato crisps in Europe from 2002 to 2016

ABSTRACT

European manufacturers’ data on acrylamide in potato crisps from 2002 to 2016 were analysed. A previous study showed a 53% reduction in mean acrylamide levels from 763 ng g^?1 in 2002 to 358 ng g^?1 in 2011. Analysis of data from the longer period showed that since 2011 there has been a levelling off, with the mean level for 2016 being 412 ng g^?1 (still a 46% reduction from 2002), suggesting that the most effective acrylamide reduction measures had been devised and implemented by 2011. There were similar trends in the 90^th and 95^th quantile values, with the 90^th quantile values being below 1000 ng g^?1 (the European Commission’s current ‘Indicative Value’ for acrylamide in potato crisps) since 2010. The proportion of samples with acrylamide above 2000 ng g^?1 fell from 4.8% in 2002 to 0.6% in 2016. Acrylamide levels showed marked seasonal variability, being highest in the first half of the year when potatoes were being used from storage, and lowest from July to September when potatoes were being harvested. Acrylamide levels were higher in thicker types of crisp in the early years of the study, but this difference disappeared in the later years, suggesting that manufacturers had acted to reduce acrylamide formation in these products. Higher values for acrylamide were recorded in north and east Europe than in the south and west up to 2013. Levels in the north and east declined in recent years, but remained higher in the north than in the other regions. The manufacturers’ data were compared with a much smaller dataset provided by the European Food Safety Authority (EFSA). Levels of acrylamide in the EFSA dataset were consistently higher than in the manufacturers’ data, possibly due to uneven sampling through the year and the seasonality of acrylamide levels.     

A two-year investigation towards an effective quality control of incoming potatoes as an acrylamide mitigation strategy in french fries

The current entrance quality control used in the french fries industry is done based on colour evaluation with a United States Department of Agriculture/Munsell colour chart (after a short frying test, typically 180°C for 3?min). On the basis of a study carried out during two consecutive potato storage seasons, the possibility of a more effective entrance control of the raw potato tubers in order to identify batches of potatoes prone to acrylamide formation was evaluated. The current entrance control was compared to two other colour evaluation methods (CIE L*a*b* colour parameters and a process-specific Agtron analyser) and to reducing sugar content determination. Seasonal variability did not affect the slopes of the linear correlation models, for most of the parameters studied. The determination of colour formation measured by the Agtron methodology and reducing sugar content allowed a better identification of batches of potatoes prone to acrylamide formation compared with the current entrance control. Different scenarios represented by decision trees for quality control measures for incoming potatoes were evaluated while considering the investigation value of 600?μg?kg?1 for french fries recently prescribed by the European Commission. Samples were categorised based on predictions of threshold values and acrylamide levels in the final product.     

Acrylamide content in fried chips prepared from irradiated and non-irradiated stored potatoes

The content of reducing sugars and asparagine, responsible for the formation of acrylamide, was determined in eight Indian potato varieties. Among these, Kufri chipsona-2 and Kufri lavkar showed the lowest level of reducing sugar (680.68 ± 56.50 mg/kg) and asparagine (2074.36 ± 122.27 mg/kg), respectively. The acrylamide content in potato chips prepared from Kufri chipsona-2, the variety that is used commercially in India for making potato chips was also the lowest. Irradiation of this variety of potatoes at the sprout inhibition dose of 60 Gy and subsequent storage for six months showed a 10.7% lower content of reducing sugars at both 14 and 4 °C. The acrylamide content was 8.41% and 6.95% lower in chips from irradiated potatoes stored at 14 and 4 °C than the corresponding non-irradiated controls. The colour of the chips was also better in irradiated potatoes as judged from the L∗ and a∗ values.     

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.     

Acrylamide in a fried potato dish (rösti) from restaurants in Zurich,Switzerland

Rösti, a fried potato product, is a large contributor to acrylamide exposure locally in Switzerland. A survey of 55 dishes prepared by 51 restaurants in the city of Zurich showed that the average rösti contained 702 µg/kg acrylamide. By analysing the content of reducing sugars in the potatoes used for frying, it is shown that with simple measures, the exposure to acrylamide could easily be reduced by factor 2 or more, while even improving the culinary experience. Though rösti is a typical dish in the German-speaking areas in Switzerland, the result may be of general interest for fried potato products which are popular in large areas of Central Europe.     

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.     

Assessment of acrylamide intake of Spanish boys aged 11–14 years consuming a traditional and balanced diet

Acrylamide is a toxic and potentially cancer causing chemical formed in thermally treated foods, especially in carbohydrate rich. New dietary habits acquired by adolescents, increasing snacking and fast food consumption, lead to a high acrylamide intake, since the composition of these meals and their processing promote its appearance. This study investigated acrylamide daily exposure in a group of Spanish male adolescents (11–14 years) consuming a balanced diet based on their food preferences but reducing snacking and fast food, aimed to determine whether acrylamide exposure was reduced by the consumption of a traditional diet. Acrylamide content of main dishes was analyzed and input per serving calculated. The Spanish potato omelette and the grilled loin of pork with fried potatoes presented the highest levels of acrylamide (128 and 111 μg/kg respectively), followed by different meals also containing potatoes or cereal derived products. The acrylamide total intake was estimated at 0.534 μg/kg body weight/day, where the highest percentage was provided by the breakfast (31.66%), the afternoon snack being the lowest contributor (16.19%). These results indicate consumption of a balanced and traditional diet, besides the well known beneficial effects on health, can also moderate acrylamide exposure and thus its possible long-term toxicological effect.     

Comparison of potato varieties between seasons and their potential for acrylamide formation

BACKGROUND: Acrylamide is a probable human carcinogen produced during food preparation, including frying of potato products. The aim of this study was to investigate the impact of seasonal variation on tuber composition and its acrylamide generation potential. RESULTS: The chemical composition of potato varieties used respectively for French fry (Bintje and Ramos) and crisp (Lady Rosetta and Saturna) production was studied throughout a storage period of 9 months during two growing seasons (2003 and 2004), in addition to their acrylamide generation potential during preparation of French fries. A significant impact of variable climatological conditions on the reducing sugar, dry matter, total free amino acid and free asparagine contents of tubers was observed. Exceptionally warm summers gave rise to a lower reducing sugar content (expressed on a dry matter basis) and thus a lower susceptibility to acrylamide generation during frying. CONCLUSION: It cannot be excluded that potato growers and the potato‐processing industry are confronted with some harvests that are more prone to acrylamide generation than others owing to climatological variability, thus confirming the importance of a multifactorial approach to mitigate acrylamide generation in potato products. Copyright © 2007 Society of Chemical Industry