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.     

Effect of water content and temperature on glucosinolate degradation kinetics in broccoli (Brassica oleracea var. italica)

The effect of water content and temperature on glucosinolate thermal degradation in broccoli (Brassica oleracea var. italica) was investigated. Broccoli was freeze dried obtaining batches with water content between 13% and 82% (a_w from 0.32 to 0.99). These samples were heated at different temperatures (from 60 to 120 °C) and glucosinolate levels were monitored. To rule out enzymatic breakdown, myrosinase was inactivated prior to heating. Degradation could be described by first-order kinetics for all glucosinolates and all water contents. In the temperature range 60–100 °C the sample with 13% showed the lowest degradation rate, whereas at 120 °C the degradation rate increased with the water content. This particular behavior was reflected by the high activation energy value of the driest sample. Several hypotheses to explain the observed behavior are discussed.     

Acrylamide and methylglyoxal formation in potato chips by microwaving and frying heating

In our present paper, the effect of important α‐dicarbonyl compounds of methylglyoxal on the formation of acrylamide was quantified in potato chips systems. Methylglyoxal was regarded as the main α‐dicarbonyl compound, and its formation was detected by HPLC method. There heating methods were used to study the effect on acrylamide formation. The results showed that microwaving treatment could form more acrylamide compared with frying method. After 2 min of microwaving treatment at 700 W, the acrylamide content was sharply increased from 1.77 ± 0.37 to 72.93 ± 0.72 μmol kg^?1. Microwaving treatment would promote the formation of methylglyoxal compared with frying treatment at 160 and 180 °C in potato chips. A typical linear growth curve prepared by plotting acrylamide levels vs. methylglyoxal content formed under different heating condition was observed: y = ?41.33 + 0.17x (r = 0.965). This study revealed for the first time that there is a significant correlation between methylglyoxal and acrylamide in potato chips, thus confirming the important role of dicarbonyls in the formation of acrylamide in potato chips.     

Acrylamide Formation in Foods during Thermal Processing with a Focus on Frying

This paper summarizes the current state of knowledge on acrylamide formation in foods during thermal processing. The main pathway of acrylamide formation in foods is linked to the Maillard reaction, and in particular, the amino acid asparagine. Effects of several factors related to food composition and processing conditions on the formation levels of acrylamide, and also, other quality characteristics in thermally processed foods are discussed in detail. From a process control point of view, it is also addressed that there is a need to develop viable models for the estimation of acrylamide contents in heated foods during the stages of process design and optimization. Fried potato products, as one of the most encountered category of thermally processed foods, are specifically emphasized for acrylamide formation, potential ways of mitigation, and modeling its formation during frying.     

A kinetic model for browning in the baking of biscuits: Effects of water activity and temperature

We describe here a rigorous and fundamental approach to the extraction of kinetic parameters when solid foods undergo colour change, and provide a generic basis for other studies on foods. Freeze-dried ‘digestive’ biscuit dough samples were used for kinetic studies of browning during the baking process. Browning data were recorded (temperature T: 105-135 °C; water activity a_w: 0.04-0.15; t=0-26 min) as colorimeter R, G, B values (reflectance), in order to obtain rates of browning for numerical integration within the kinetic model. Reflectances were weighted using the Kubelka-Munk relationship so as to provide data which are linear with respect to concentration. It was postulated that the rate of formation of coloured product changes according to a first-order kinetic process but is largely zero order within the observation period. An activation energy of 105 kJ/mol was obtained but the rate of browning was independent of a_w under the conditions investigated. It was thus possible to model the R, G, and B values very accurately within a kinetic run, and to extract kinetic parameters for doughs with varying sugar concentration. These parameters can now be used to predict the final colour (as R, G, B or L, a, b) for any given temperature-time profile.     

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.     

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.     

Dietary Acrylamide and Cancer Risk in Humans: A Review

In April 2002, researchers from the Swedish National Food Administration reported that they had detected elevated levels of acrylamide in commonly consumed baked and fried foods. Acrylamide is known as a neurotoxin in humans and as a carcinogen in experimental animals, and it is classified as a probable human carcinogen by the International Agency for Research on Cancer (IARC, 1994). Therefore, the discovery that the compound forms naturally during high-heat cooking of starchy foods caused substantial alarm in Sweden and worldwide. Within months of the initial Swedish report, national governments and food companies began their own investigations on acrylamide in foods and discussed the potential impact of dietary acrylamide on the public’s health. The discovery also provoked public debate among scientists about the importance of the finding because of the relative lack of data in humans on the one hand and the knowledge that acrylamide in high doses is genotoxic in cell and animal studies on the other. Since 2002, researchers have engaged in a wide range of studies spanning across disciplines. In this review, we summarize the current state of knowledge on acrylamide in foods. We discuss the formation and intake of acrylamide in foods, present evidence for carcinogenicity in cell and animal studies, and examine the findings from epidemiological studies of occupational and dietary exposures. We conclude with a discussion of future directions in the field.

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Zusammenfassung (Redaktion). Im April des Jahres 2002 berichteten Forscher der nationalen, schwedischen Lebensmittelbeh?rde über den erh?hten Gehalt an Acrylamid in gebackenen oder frittierten, üblicherweise verzehrten Lebensmitteln. Acrylamid gilt in Bezug auf den Menschen als Neurotoxin und hat sich in Tierversuchen als karzinogen erwiesen; die International Agency for Research on Cancer (IARC) hat Acrylamid als potenziell karzinogen für den Menschen eingestuft. Daher hat die Entdeckung, dass sich diese Substanz natürlicherweise beim starken Erhitzen von st?rkereichen Lebensmitteln bildet, erhebliche Beunruhigung in Schweden und weltweit ausgel?st. Schon wenige Monate, nachdem der schwedische Report über Acrylamid in Lebensmitteln erschienen war, wurden von den Regierungen verschiedener Staaten und auch von der Lebensmittelindustrie eigene, diesbezügliche Forschungsprogramme veranlasst. Der potenzielle Einfluss des Acrylamids in Lebensmitteln auf die Gesundheit der Bev?lkerung wurde ebenso diskutiert wie die Bedeutung dieser Entdeckung angesichts der Tatsache, dass für Menschen zwar kaum Daten vorliegen, dass aber Acrylamid in hohen Dosen auf Zellkulturen und Versuchstiere genotoxisch wirkt. Seit dem Jahr 2002 ist diesen offenen Fragen im Rahmen mehrerer Disziplin-übergreifender Forschungsvorhaben nachgegangen worden. Im vorliegenden Review wird der derzeitige Wissensstand über Acrylamid in Lebensmitteln vorgestellt. Die Autoren diskutieren die Bildung von Acrylamid in und seine Aufnahme mit Lebensmitteln, besprechen seine karzinogenen Eigenschaften in Versuchen mit Zellkulturen oder Tieren und analysieren die Ergebnisse epidemiologischer Studien. Zukünftige Entwicklungen werden er?rtert.

     

The effect of water activity on cholesterol oxidation in spray- and freeze-dried egg powders

The aim of the paper was to estimate the effect of water activity in spray- and freeze-dried whole egg and egg yolk powders on cholesterol oxidation during 3-months of storage at room temperature.     

Modelling the effect of temperature and water activity in the growth boundaries of Aspergillus ochraceus and Aspergillus parasiticus

The aim of this work was to model the growth of Aspergillus parasiticus and Aspergillus ochraceus, both mycotoxin producers, near to the growth/no growth boundaries and validate those models in sterile maize grain, peanuts and coffee beans. Malt extract agar was adjusted to six different water activities: 0.93, 0.91, 0.89, 0.87, 0.85 and 0.80. Plates were incubated at 10, 15, 20, 25, 30, 37 and 42 °C. For each of the 42 conditions, 10 Petri dishes were inoculated. Both kinetic and probability models were applied to colony growth data. The results of the present study indicate that the developed probability modelling approach could be satisfactorily employed to quantify the combined effect of temperature and water activity on the growth responses of A. ochraceus and A. parasiticus. However, validation of kinetic results led to poor goodness of prediction. In this study, the validation samples were placed near to the expected boundaries of the models in order to test them under the worst situation. Probability of growth prediction under extreme growth conditions was somewhat compromised, but it can be considered acceptable.     

Prediction of water activity in vegetables creams: Note 1

A study on empirical models for a _w value prediction, directly correlated to humectant substances concentration, was carried out in model systems and vegetables food. The test, performed for different a _w values predicted on aqueous solution, aqueous extract and vegetables creams of mushroom (Cv. Champignon), showed a high accuracy of proposed model. In fact the values of correlation coefficient (r), were always greater than 0.985, and the maximum pure error was 0.014.     

Effect of crust temperature and water content on acrylamide formation during baking of white bread: Steam and falling temperature baking

The effect of crust temperature and water content on acrylamide formation was studied during the baking of white bread. To assess the effect of over-baking, we used a full factorial experimental design in which the baking time was increased by 5 and 10 min at each baking temperature. Additional experiments were performed with steam baking and falling temperature baking. Immediately after baking, the crust was divided into the outer and inner crust fractions, and the water content and acrylamide concentration of each fraction was measured. The outer crust had a significantly lower water content and higher acrylamide concentration than the inner crust did. Crust temperature in combination with water content had a significant effect on acrylamide formation, higher temperatures resulting in higher acrylamide concentrations. However, at very high temperatures and lower water contents, acrylamide concentration was observed to decrease, though the bread colour was then unacceptable for consumption. Steam and falling temperature baking, on the other hand, decreased the acrylamide content while producing bread crust with an acceptable colour. The lowest acrylamide values and an acceptable crust colour were produced by steam baking.     

Effect of water activity on carotenoid degradation in dehydrated carrots

The effect of water activity on the stability of carotenoids in dehydrated carrots was studied.     

Evaluation of sample preparation methods for water activity determination in jerky and kippered beef: A research note

Commercially available packaged whole muscle beef jerky, chopped and formed beef jerky, and kippered beef steak were obtained from retail stores to determine the effect of two sample preparation methods on water activity (a_w). Intact samples were prepared by cutting product into a hexagonal shape with a 3.2 cm diameter. Diced samples were prepared by cutting the product into 0.4 × 0.4 cm squares. Whole muscle jerky a_w was higher (0.016 units; P < 0.001) using the intact method compared to the diced method. There was no difference (P > 0.05) in a_w levels between the two preparation methods for chopped and formed jerky or kippered beef steak. An intact sample preparation method is recommended for a_w determination of whole muscle jerky to obtain a more conservative value, especially if a_w is near the margin of safety.     

Acrylamide and 5-hydroxymethylfurfural (HMF): A review on metabolism, toxicity, occurrence in food and mitigation strategies

Neo-formed contaminants (NFCs) are compounds forming during heating or preservation processes and exhibiting possible harmful effects to humans. Among the several NFCs described in literature, Acrylamide and 5-hydroxymethylfurfural (HMF) have attracted the attention of the scientific community in recent years. Both acrylamide and HMF are considered as probably or potentially carcinogenic to humans or might be metabolized by humans to potentially carcinogenic compounds. Acrylamide and HMF are mainly formed through Maillard Reaction and can be regarded as the most important heat-induced contaminants occurring in bread and bakery products. Acrylamide is carcinogen in rodent and some recent epidemiological studies have highlighted the association between dietary acrylamide and an increased risk of some types of cancer. HMF has been recently shown to be converted in vivo to 5-sulfoxymethylfurfural (SMF) which is a genotoxic compound. Dietary intake of HMF is in the order of mg/kg far above that of other food toxicants. In this paper, the latest available data on acrylamide and HMF have been reviewed focusing on available mitigation strategies, metabolism, dietary exposure, and toxicity. The results from the epidemiological studies about acrylamide and cancer risk and their relevance have been discussed, the major gaps of knowledge have been identified and the perspective of ongoing and future research was established.     

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.     

热加工食品中丙烯酰胺残留及安全性评价

自从2002年发现某些热加工食品中含有丙烯酰胺以来,世界上许多国家的科学家围绕这个问题进行了很多的研究工作.本文阐述了丙烯酰胺在食品加工中的形成机制和在食品加工过程中的残留和安全性评价,并提出了在食品加工中降低丙烯酰胺含量的一些措施.     

Antiplasticization effect of water in amorphous foods. A review

Water is the most effective plasticizer in food matrices, decreasing glass transition temperature (T_g) and mechanical resistance and determining a softening effect with the increasing of its concentration. However an opposite effect (i.e. hardening, toughening) could be observed in some food and in specific moisture or a_w range and this is referred to an anti-plasticization effect. Several are the possible causes for this phenomenon and various are the factors that have been recognized to affect its occurrence in a food matrix: mechanical testing method, mechanical parameter tested, type of food (composition and micro-macrostructure).     

Acrylamide in bread. Effect of prooxidants and antioxidants

Addition of 1% aqueous rosemary extract with approximately 40 mg of gallic acid equivalents or comparable addition of rosemary oil or of dried rosemary leaves to wheat dough reduced the content of acrylamide in wheat buns by 62, 67 and 57%, respectively, compared to wheat buns without rosemary. Increasing the addition of aqueous rosemary extract to 10% did not decrease the acrylamide content further compared to the addition of a 1% extract. The spice dittany showed less effect in wheat buns compared to rosemary and even increased acrylamide formation slightly. The effect of antioxidants on acrylamide formation was confirmed by addition of 1.0 mM (but not 0.1 mM) of the green tea flavonoids epicatechin or epigallocatechin gallate to an aqueous food model. Free radicals were detected by ESR using the spin trap α-(4-Pyridyl 1-oxide)-N-tert-butylnitrone (POBN) in an aqueous model system of 0.060 M glucose and 0.060 M asparagine heated under conditions generating acrylamide, further confirming the impact of free radical intermediates in formation of acrylamide. A modest effect of the peroxides in oxidized oil on acrylamide elimination was observed pointing towards an oxidative induced polymerization of acrylamide. The impact of oxidative processes on acrylamide elimination should not be neglected, since oxidized vegetable oil seems to promote degradation of acrylamide.