Impact of blanching and frying heating rate/time on the antioxidant capacity and (poly)phenols of cardoon stalks (cynara cardunculus L. var. altilis DC)

This study assessed the influence of blanching and frying heating rate/time on the antioxidant capacity and (poly)phenols of cardoon stalks (Cynara cardunculus L. var. altilis DC). Blanching (98 °C, 30 s) increased the total native chlorogenic acids content (1.2-fold vs raw cardoon), with no significant changes in DPPH antioxidant capacity, but with a decrease in ABTS antioxidant capacity (0.6-fold). Specifically, total di-caffeoylquinic acids (CQAs) increase (1.6-fold) counterbalanced the losses of 5-CQA (0.8-fold). All frying conditions (t85°C = 5, 12 or 10 min, ttotal = 15, 15 or 30 min, respectively) decreased the antioxidant capacity (0.5–0.7-fold in DPPH, 0.5–0.9-fold in ABTS) of cardoon, but increased total flavonoid amount (3.6–3.7-fold) that remained at low levels. The Short (15 min) and Intense-heat Frying (t85°C = 5 min) favoured the release of chlorogenic acids, particularly 5-CQA, from the food matrix. However, a longer frying process (30 min) induced an almost complete degradation of di-CQAs. Thus, it is desirable to limit the frying duration. When blanching and frying were combined, a higher thermal degradation of (poly)phenols was observed, but the Short and Intense-heat Frying remained the most suitable. This study highlights the importance of selecting optimal culinary conditions for vegetables that favour a high content on bioactive compounds and, therefore, their potential healthy properties

Catabolism of raw and cooked green pepper (Capsicum annuum) (poly)phenolic compounds after simulated gastrointestinal digestion and fecal fermentation.

A total of 21 (poly)phenolic compounds (free and bound) were quantified in raw, olive oil fried, sunflower oil fried and griddled green pepper before and after a simulated gastrointestinal digestion. Flavonoids, particularly quercetin rhamnoside, were the main compounds. The bioaccessibility of (poly)phenolic compounds after gastrointestinal digestion was higher in cooked (>82%) than in raw (48%) samples, showing a positive effect of heat treatment on the release of (poly)phenols from the vegetal matrix. Additionally, a faecal fermentation was carried out for 24h. A time-dependent microbial metabolic activity was observed, which resulted firstly (<5h) in the hydrolysis of flavonoid glycosides and then in the formation of 3 catabolites, namely 3,4-dihydroxybenzoic acid, dihydrocaffeic acid and 3-(3′-hydroxyphenyl)propionic acid, this being by far the most abundant. Catabolic pathways for colonic microbial degradation of flavonoids and hydroxycinnamic acids have been proposed. Griddled pepper showed the highest amount of (poly)phenols both after gastrointestinal digestion and colonic fermentation

Effect of frying process on furan content in foods and assessment of furan exposure of Spanish population

Furan content in eight bread-coated frozen foods (ham croquettes, squid rings, tuna pasties, churros, nuggets, fish fingers, onion rings and san jacobos) deep-fried in fresh and reheated olive oil, and in five cooked vegetables was evaluated. Deep fried foods showed the highest levels of furan between 12 μg kg-1 (tuna pasties) and 172 μg kg-1 (onion rings), with a furan increase tendency when reheated oil was used. In vegetables, furan was only found at low level in griddled onion (3.5 μg kg-1). The lower temperature applied (< 150ºC) in comparison to that of the deep-fried foods (190 ºC), the furan volatilization during longer time cooking (15 min vs 6 min) together with the food composition differences might explain the low furan content in vegetables. As a preliminary approach for risk assessment, the margin of exposure (MOE) was calculated. The total daily intake of furan by Spanish population (239-4372 ng/kg bw/day) with MOEs below 10,000 indicates a human public health concern. However, MOEs for fried foods showed that furan could suppose a possible health risk only in people with a high consumption of these products. Nevertheless, further studies should be developed to provide furan exposure data of other fried foods

Influence of extraction process on antioxidant capacity of spent coffee

Spent coffee that is produced in tons by restaurants and cafeterias, and consumers at domestic levels, could be a good opportunity to have an important source of natural antioxidants. The main aim of this work was to study the influence of several process factors on the antioxidant capacity extraction from spent coffee. Total phenolic compounds, radical scavenging activity (ABTS and DPPH) and browned compounds (Abs 420 nm) of spent coffee extracts obtained with continuous (Soxhlet 1 h and 3 h) and discontinuous methods (solid-liquid extraction and filter coffeemaker), several solvents (water, ethanol, methanol and their mixtures), successive extractions, and water with different pHs (4.5, 7.0 and 9.5) were carried out. Spent coffee extracts with the highest antioxidant capacity were obtained after one extraction with neutral water (pH 7.0) in a filter coffeemaker (24 g spent coffee per 400 mL water). Furthermore, spent coffee defatting and extract lyophilization allowed us to obtain spent coffee extracts powder with high antioxidant capacity that can be used as an ingredient or additive in food industry with potential preservation and functional properties

Influence of heat treatment on antioxidant capacity and (poly)phenolic compounds of selected vegetables

The impact of cooking heat treatments (frying in olive oil, frying in sunflower oil and griddled) on the antioxidant capacity and (poly)phenolic compounds of onion, green pepper and cardoon, was evaluated. The main compounds were quercetin and isorhamnetin derivates in onion, quercetin and luteolin derivates in green pepper samples, and chlorogenic acids in cardoon. All heat treatments tended to increase the concentration of phenolic compounds in vegetables suggesting a thermal destruction of cell walls and sub cellular compartments during the cooking process that favor the release of these compounds. This increase, specially that observed for chlorogenic acids, was significantly correlated with an increase in the antioxidant capacity measured by DPPH (r=0.70). Griddled vegetables, because of the higher temperature applied during treatment in comparison with frying processes, showed the highest amounts of phenolic compounds with increments of 57.35%, 25.55% and 203.06% compared to raw onion, pepper and cardoon, respectively

Risks for public health related to the presence of furan and methylfurans in food

EFSA wishes to thank the hearing experts: Diana Doell and Ruud Woutersen and EFSA staff member: José Cortinas Abrahantes for the support provided to this scientific output. The CONTAM Panel acknowledges all European competent institutions and other stakeholders that provided occurrence data on furan and methylfurans in food, and supported the data collection for the Comprehensive European Food Consumption Database. Adopted: 20 September 2017Peer reviewedPublisher PD

Impact of heat treatment on selected vegetables: bioaccessibility of (poly)phenolic compounds after in vitro gastrointestinal digestion and colonic microbiota action, and furan occurrence

Plant foods are the main source of dietary antioxidants, including (poly)phenolic compounds, with health properties. However, their bioaccessibility might be affected by culinary processes, as well as by gastrointestinal digestion and microbiota. Additionally, heat treatment induces the formation of volatile compounds, among them furan which has been classified as a possibly carcinogenic to humans (group 2B) by the International Agency for Research on Cancer. Therefore, the main aim of the present research was to investigate the influence of heat treatment (frying and griddling) on the antioxidant capacity, nutritional composition and (poly)phenolic compounds in selected vegetables (yellow onion (Allium cepa), Italian green pepper (Capsicum annuum) and cardoon stalks (Cynara. cardunculus L.)), as well as their bioaccessibility after a simulated gastrointestinal digestion and colonic microbiota action. Moreover, the presence of furan in heat treated vegetables in comparison with that formed during deep-frying in bread coated frozen foods was also investigated. A total of 7, 24 and 25 free and bound (poly)phenolic compounds were identified and quantified in both raw and cooked onion, green pepper and cardoon, respectively. The main (poly)phenolic compounds were quercetin glucosides (approx. 90%) in onion, quercetin and luteolin derivates (>90%) in green pepper, and chlorogenic and other phenolic acids (approx. 99%) in cardoon. Heat treatments, especially griddling process, tended to increase the total (poly)phenolic compounds in vegetables, and consequently their antioxidant capacity, since DPPH and (poly)phenols were correlated (r=0.70, p82% in cooked pepper vs 48% in raw one) and cardoon (60-67% in cooked cardoon vs 2% in raw one). After in vitro gastrointestinal digestion, both griddled green pepper and griddled cardoon still maintained the highest amount of (poly)phenolic compounds (9.447 and 41.853 µmol (poly)phenolic compounds/g dm, respectively). Gut microbiota exerted a high metabolic activity resulting in a large and rapid degradation of (poly)phenolic compounds into new metabolites, being 3-(3’- hydroxyphenyl)propionic acid by far the most abundant catabolite in all samples after 24 h of fecal incubation. Catabolic pathways for colonic microbial degradation of flavonoids and chlorogenic acids have been proposed. Griddled vegetables were the samples with the highest amount of bioaccessible (poly)phenolic compounds even after the fecal fermentation. Finally, frying process did not result in the formation of furan in vegetables, while low amount (3.5 µg kg-1 in gridlled onion) or traces of this compound were formed in vegetables during griddling. Therefore, cooked vegetables do not represent a high exposure to furan. In contrast, deep-frying process induced the formation of considerable amounts of furan in bread-coated foods (12 µg kg-1 (tuna pasties)-172 µg kg-1 (onion rings)), implying a health risk in Spanish population groups with a high consumption of frozen precooked products

Impact of blanching and frying heating rate/time on the antioxidant capacity and (poly)phenols of cardoon stalks (cynara cardunculus L. var. altilis DC)

This study assessed the influence of blanching and frying heating rate/time on the antioxidant capacity and (poly)phenols of cardoon stalks (Cynara cardunculus L. var. altilis DC). Blanching (98 °C, 30 s) increased the total native chlorogenic acids content (1.2-fold vs raw cardoon), with no significant changes in DPPH antioxidant capacity, but with a decrease in ABTS antioxidant capacity (0.6-fold). Specifically, total di-caffeoylquinic acids (CQAs) increase (1.6-fold) counterbalanced the losses of 5-CQA (0.8-fold). All frying conditions (t85°C = 5, 12 or 10 min, ttotal = 15, 15 or 30 min, respectively) decreased the antioxidant capacity (0.5–0.7-fold in DPPH, 0.5–0.9-fold in ABTS) of cardoon, but increased total flavonoid amount (3.6–3.7-fold) that remained at low levels. The Short (15 min) and Intense-heat Frying (t85°C = 5 min) favoured the release of chlorogenic acids, particularly 5-CQA, from the food matrix. However, a longer frying process (30 min) induced an almost complete degradation of di-CQAs. Thus, it is desirable to limit the frying duration. When blanching and frying were combined, a higher thermal degradation of (poly)phenols was observed, but the Short and Intense-heat Frying remained the most suitable. This study highlights the importance of selecting optimal culinary conditions for vegetables that favour a high content on bioactive compounds and, therefore, their potential healthy properties