Evolution of mechanical and optical properties of french fries obtained by hot air-frying

The aim of this study was to analyse the influence of frying technique (air-frying and deep oil-frying) and type of pre-treatment (freezing and blanching) on the evolution of mechanical and optical properties of French fries. The results showed that the chromatic parameters, a* and b*, experimented an increase regardless of the frying method. The increase in a* was significantly higher in deep-oil frying as a result of Maillard's reactions. The texture analysis reported a first stage of initial softening related to starch gelatinization followed by a second stage where the maximum force increased due to the gradual formation of a crust, both stages being faster in deep-oil frying. Pre-frozen potatoes presented the highest value of maximum force parameter independent of the type of fryingAuthors would like to thank to the Universitat Politecnica de Valencia (PAID-06-09-2876) for the financial support given to this investigation.Heredia Gutiérrez, AB.; Castelló Gómez, ML.; Argüelles Foix, AL.; Andrés Grau, AM. (2014). Evolution of mechanical and optical properties of french fries obtained by hot air-frying. LWT - Food Science and Technology. 57(2):755-760. https://doi.org/10.1016/j.lwt.2014.02.038S75576057

Effects of nitrogen and sulfur fertilization on free amino acids, sugars, and acrylamide-forming potential in potato

Nitrogen (N) fertilizer is used routinely in potato (Solanum tuberosum) cultivation to maximize yield. However, it also affects sugar and free amino acid concentrations in potato tubers, and this has potential implications for food quality and safety because free amino acids and reducing sugars participate in the Maillard reaction during high-temperature cooking and processing. This results in the formation of color, aroma, and flavor compounds, but also some undesirable contaminants, including acrylamide, which forms when the amino acid that participates in the final stages of the reaction is asparagine. Another mineral, sulfur (S), also has profound effects on tuber composition. In this study, 13 varieties of potato were grown in a field trial in 2010 and treated with different combinations of N and S. Potatoes were analyzed immediately after harvest to show the effect of N and S fertilization on concentrations of free asparagine, other free amino acids, sugars, and acrylamide-forming potential. The study showed that N application can affect acrylamide-forming potential in potatoes but that the effect is type- (French fry, chipping, and boiling) and variety-dependent, with most varieties showing an increase in acrylamide formation in response to increased N but two showing a decrease. S application reduced glucose concentrations and mitigated the effect of high N application on the acrylamide-forming potential of some of the French fry-type potatoes

Effects of water availability on free amino acids, sugars, and acrylamide-forming potential in potato

Irrigation is used frequently in potato cultivation to maximize yield, but water availability may also affect the composition of the crop, with implications for processing properties and food safety. Five varieties of potatoes, including drought-tolerant and -sensitive types, which had been grown with and without irrigation, were analyzed to show the effect of water supply on concentrations of free asparagine, other free amino acids, and sugars and on the acrylamide-forming potential of the tubers. Two varieties were also analyzed under more severe drought stress in a glasshouse. Water availability had profound effects on tuber free amino acid and sugar concentrations, and it was concluded that potato farmers should irrigate only if necessary to maintain the health and yield of the crop, because irrigation may increase the acrylamide-forming potential of potatoes. Even mild drought stress caused significant changes in composition, but these differed from those caused by more extreme drought stress. Free proline concentration, for example, increased in the field-grown potatoes of one variety from 7.02 mmol/kg with irrigation to 104.58 mmol/kg without irrigation, whereas free asparagine concentration was not affected significantly in the field but almost doubled from 132.03 to 242.26 mmol/kg in response to more severe drought stress in the glasshouse. Furthermore, the different genotypes were affected in dissimilar fashion by the same treatment, indicating that there is no single, unifying potato tuber drought stress response

Acrylamide formation and quality properties of chitosan based batter formulations

[EN] The potential of chitosan to mitigate acrylamide formation has been already demonstrated. The two main objectives of this study were: 1) to select the most adequate degree of deacetylation (DD) and molecular weight (Mw) of chitosan based on acrylamide mitigation criteria and 2) to evaluate the influence of including chitosan in batter formulations on some important technological parameters of raw batters (flow behavior and water retention capacity) and on some quality properties of fried batters (oil uptake, color and texture). Results in model systems showed that chitosans with higher deacetylation degree (86.5 and 92.8%) achieved a decrease of acrylamide between 44 and 81%, depending on reaction time, compared to the control (without chitosan). Furthermore, acid hydrolysis process of chitosan was found to negatively affect its inhibitory effect on acrylamide formation independently of the molecular weight. Raw chitosan based batter formulations presented higher consistency and water retention capacity than the control; chitosan addition to batters reduced the hardening of the fried samples during the post-frying cooling period. No significant differences in water loss were observed between batters with or without added chitosan; however, chitosan-batter formulations showed lower oil uptake during frying as compared to control samples.The authors thank the gs1:Universitat Politecnica de Valencia for the PhD scholarship given to Mariola Sansano Tomas.Sansano Tomás, M.; Castelló Gómez, ML.; Heredia Gutiérrez, AB.; Andrés Grau, AM. (2016). Acrylamide formation and quality properties of chitosan based batter formulations. Food Hydrocolloids. 66:1-7. doi:10.1016/j.foodhyd.2016.10.019S176

Exposure assessment of process-related contaminants in food by biomarker monitoring

Exposure assessment is a fundamental part of the risk assessment paradigm, but can often present a number of challenges and uncertainties. This is especially the case for process contaminants formed during the processing, e.g. heating of food, since they are in part highly reactive and/or volatile, thus making exposure assessment by analysing contents in food unreliable. New approaches are therefore required to accurately assess consumer exposure and thus better inform the risk assessment. Such novel approaches may include the use of biomarkers, physiologically based kinetic (PBK) modelling-facilitated reverse dosimetry, and/or duplicate diet studies. This review focuses on the state of the art with respect to the use of biomarkers of exposure for the process contaminants acrylamide, 3-MCPD esters, glycidyl esters, furan and acrolein. From the overview presented, it becomes clear that the field of assessing human exposure to process-related contaminants in food by biomarker monitoring is promising and strongly developing. The current state of the art as well as the existing data gaps and challenges for the future were defined. They include (1) using PBK modelling and duplicate diet studies to establish, preferably in humans, correlations between external exposure and biomarkers; (2) elucidation of the possible endogenous formation of the process-related contaminants and the resulting biomarker levels; (3) the influence of inter-individual variations and how to include that in the biomarker-based exposure predictions; (4) the correction for confounding factors; (5) the value of the different biomarkers in relation to exposure scenario’s and risk assessment, and (6) the possibilities of novel methodologies. In spite of these challenges it can be concluded that biomarker-based exposure assessment provides a unique opportunity to more accurately assess consumer exposure to process-related contaminants in food and thus to better inform risk assessment