Catarina Petisca

Effect of Beer/Red Wine Marinades on the Formation of Heterocyclic Aromatic Amines in Pan-Fried Beef

The effect of beer or red wine marinades on the reduction of heterocyclic aromatic amines (HAs) formation in pan-fried beef was compared. The cooking experiments were performed under well-controlled temperature and time conditions. The samples were analyzed for HAs contents using solid-phase extraction and high-performance liquid chromatography-diode array detection/fluorescence detection. Unmarinated samples cooked in similar conditions provided reference HAs levels. Marinating with beer or with red wine resulted in decreased levels of HAs. The amount of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline reduced significantly, respectively, around 88 and 40% after 6 h of marinating with beer or with wine. High variations were observed for reductions of AalphaC, ranging between 7 and 77%. Only beer marinade significantly reduced the levels of 4,8-DiMeIQx at 1, 2, and 4 h of marinating. Multivariate statistical treatment of results indicated that beer can be more efficient on the reduction of some HAs formation. In addition, results from descriptive sensory analysis of unmarinated and 2 h marinated beef samples, tested for by two trained sensory panels, pointed to beer marinade as the most adequate for maintaining the usual overall appearance and quality of the pan-fried steaks.

Quantification of furanic compounds in coated deep-fried products simulating normal preparation and consumption: optimisation of HS-SPME analytical conditions by response surface methodology.

The validation of a method for the simultaneous quantification of furanic compounds in coated deep-fried samples processed and handled as usually consumed is presented. The deep-fried food was grinded using a device that simulates the mastication, and immediately analysed by headspace solid phase microextraction coupled to gas chromatography-mass spectrometry. Parameters affecting the efficiency of HS-SPME procedure were selected by response surface methodology, using a 2(3) full-factorial central composite design. Optimal conditions were achieved using 2g of sample, 3g of NaCl and 40min of absorption time at 37°C. Consistency between predicted and experimented values was observed and quality parameters of the method were established. As a result, furan, 2-furfural, furfuryl alcohol and 2-pentylfuran were, for the first time, simultaneously detected and quantified (5.59, 0.27, 10.48 and 1.77μgg(-1) sample, respectively) in coated deep-fried fish, contributing to a better understanding of the amounts of these compounds in food.

Impact of cooking and handling conditions on furanic compounds in breaded fish products.

This study evaluates the influence of cooking and handling conditions on the quantity of furanic compounds (furan, 2-furfural, furfuryl alcohol, 2-pentylfuran, 5-hydroxymethylfurfural) in breaded fish products. Oven-baking and reheating in the microwave lead to low furanic compounds formation in comparison with deep-frying. The use of olive oil for deep-frying promoted higher levels of furanic compounds than sunflower oil. The amounts of these compounds diminished as the temperature and time of deep-frying decreased as well as after a delay after deep-frying. Thus, the generation of furanic compounds can be minimized by adjusting the cooking method and conditions, such as using an electric oven, deep-frying in sunflower oil at 160°C during 4min, or waiting 10min after cooking. However, these conditions that reduce furanic compounds levels also reduce the content of volatile compounds related to the aroma and flavour of fried foods. In this sense, new efforts should be done to reduce the formation of furanic compounds without being detrimental to the volatile profile.

EXTRACTION, DETECTION AND QUANTIFICATION OF HETEROCYCLIC AROMATIC AMINES IN PORTUGUESE MEAT DISHES BY HPLC/DIODE ARRAY

Abstract The present paper describes the results obtained in the analyses of heterocyclic aromatic amines (HAs) in bovine meat dishes prepared by three different coking methods; usually ingredients such as, salt, garlic, wine, olive oil, onion, and tomato were added. Control meat samples (cooked without ingredients) were also prepared. Analyses were performed by HPLC/diode array and detection of the eluted HAs was performed at 263 nm. The calibration graphs for fourteen amines injected into the column were linear up to approximately 2.0 ng/μL and the detection limits (signal‐to‐noise ratio 3:1) ranged from 0.06 to 0.4 ng injected. Nine HAs, namely 2‐amino‐3‐methylimidazo[4,5‐f]quinoline (IQ), 2‐amino‐3,8‐dimethylimidazo[4,5‐f]quinoxaline (MeIQx), 2‐amino‐3,4,8‐trimethylimidazo[4,5‐f]quinoxaline (4,8‐DiMeIQx), 2‐amino‐1‐methyl‐6‐phenylimidazol[4,5]pyridine (PhIP), 3‐amino‐1,4‐dimethyl‐5H‐Pyrido[4,3‐b]indole (Trp‐P‐1), 3‐amino‐1‐methyl‐5H‐Pyrido[4,3‐b]indole (Trp‐P‐2), 2‐amino‐9H‐Pyrido [2,3‐b]indole (AαC) 2‐amino‐3‐methyl‐9H‐Pyrido [2,3‐b]indole (MeAαC), 2‐amino‐6‐methyldipyrido[1,2‐a:3′,2′‐d]imidazole (Glu‐P‐1) were encountered in meat samples. A paired Students t‐test showed no significant differences on HAs levels (p > 0.05) of control meat samples (cooked without ingredients) and meat samples cooked with ingredients usually in the Portuguese diet and rich in antioxidants. Changes in cooking habits are needed to make possible the use of ingredients not only as flavoring but also as protective agents against HAs formation during domestic cooking.

Changes in chemical composition of frozen coated fish products during deep-frying.

Abstract This work evaluates the influence of deep-frying coated fish products on total fat, fatty acid (FA) and amino acid profile, and on the formation of volatile compounds, with special attention on furan and its derivatives due to their potential harmful characteristics. As expected, deep-frying in sunflower oil increased linoleic acid content, but total fat amount increased only by 2% on a dry basis. Eicosapentanoic and docosahexanoic acids were preserved while γ- and α-linoleic acids were oxidised. Deep-frying also induces proteolysis, releasing free AA, and the formation of volatile compounds, particularly aldehydes and ketones arising from polyunsaturated FA. In addition, high quantities of furanic compounds, particularly furan and furfuryl alcohol, are generated during deep-frying coated fish. The breaded crust formed could contribute simultaneously for the low uptake of fat, preservation of long chain n−3 FA, and for the high amounts of furanic compounds formed during the deep-frying process.

Effect of solvent to sample ratio on total lipid extracted and fatty acid composition in meat products within different fat content.

The effect of solvent to sample ratio on total extracted lipids and fatty acid (FA) composition in meat products with different fat contents was evaluated. Total lipids were extracted according to the Folch et al. (1957) method, using a 20:1 ratio of chloroform:methanol (2:1, v/v) to sample (A), and also testing the solvent:sample ratio of 10:1 (B). Higher amounts of total lipids and total FA from neutral lipids were obtained using the A ratio, which could be due to an insufficient chloroform:dry-weight sample proportion which could be insufficient for solubilizing the total amount of lipids. In the polar lipid fraction, the total amount of FA was higher using the B rather than the A ratio, which may be caused by the higher volume of added water when using A than B. When studying the FA composition of different lipid fractions, the volume of both the solvent and the water for total lipid extraction should be considered.

Study of hydroxymethylfurfural and furfural formation in cakes during baking in different ovens, using a validated multiple-stage extraction-based analytical method.

A procedure for extraction of hydroxymethylfurfural (HMF) and furfural from cakes was validated. Higher yield was achieved by multiple step extraction with water/methanol (70/30) and clarification with Carrez I and II reagents. Oven type and baking time strongly influenced HMF, moisture and volatile profile of model cakes, whereas furfural content was not significantly affected. No correlation was found between these parameters. Baking time influenced moisture and HMF formation in cakes from traditional and microwave ovens but not in steam oven cakes. Significant moisture decrease and HMF increase (3.63, 9.32, and 41.9 mg kg(-1)dw at 20, 40 and 60 min, respectively) were observed during traditional baking. Cakes baked by microwave also presented a significant increase of HMF (up to 16.84 mg kg(-1)dw at 2.5 min). Steam oven cakes possessed the highest moisture content and no significant differences in HMF and furfural. This oven is likely to form low HMF and furfural, maintaining cake moisture and aroma compounds.

Influence of different extraction conditions and sample pretreatments on quantification of nitrate and nitrite in spinach and lettuce.

Different sample pretreatment and extraction techniques are often used for analysis of nitrates and nitrites, however, the effects of these variables have not been properly examined. Comparative investigations were carried out with the objective of finding the most suitable conditions for quantification of nitrate and nitrite in spinach and lettuce. A rapid and cost effective RP-HPLC/UV method was validated and used to select the most appropriate extraction procedure to eliminate chromatographic interferences and to evaluate the influence of different sample pretreatments on the accuracy and reproducibility of the results obtained. Similar nitrate concentrations were obtained for fresh and two weeks frozen samples. Freeze drying and oven drying pretreatment of the spinach and lettuce material was inappropriate. No nitrite was detected in either fresh, freeze dried, oven dried, and frozen spinach or lettuce.