Effect of different precooking methods on chemical composition and lipid damage of silver carp (Hypophthalmichthys molitrix) muscle

The influence of three precooking methods (steaming, oven‐baking and microwave‐cooking) on the chemical composition and lipid quality of silver carp fillets was evaluated. The changes in protein, fat and moisture were found to be significant for all the treatments (P ≤ 0.05). The iron content in the samples subjected to steam‐cooking increased; however, the other precooking methods did not change the mineral contents (P ≥ 0.05). The free fatty acid content of the fillets did not change by the different precooking methods, while thiobarbituric acid (TBA) values increased for oven‐ and microwave‐cooked fillets and remained constant in the steam‐cooked samples. Conjugated diene and browning colour formation levels significantly increased in the oven‐baked fillets. Oven‐baking and microwave‐cooking marginally affected the fatty acid composition of the silver carp. On comparing the raw and precooked fillets, steam‐cooking was found to be the best precooking method on retaining nutritional constituents.     

Effects of cooking and reheating methods on the fatty acid profile of sea bream treated with rosemary extract

BACKGROUND: The effects of rosemary extract on the fatty acid profile of sea bream fillets cooked by different methods (oven baking, grilling and pan frying) as well as the effects of different reheating methods (microwave and conventional oven) on the fatty acid composition of fish after frozen storage for 4 months were investigated. RESULTS: The proportion of saturated fatty acids increased only slightly in fried samples but significantly in oven‐baked and grilled samples, while the proportion of polyunsaturated fatty acids (PUFAs) increased significantly in fried samples but only slightly in oven‐baked and grilled samples. The proportion of monounsaturated fatty acids remained relatively constant after cooking. Of the fatty acids analysed, the most significant increases (P < 0.05) were observed in C18:1n‐9 and C18:2n‐6 and the most significant decreases (P < 0.05) in C14:0, C16:1, C20:5n‐3 and C22:6n‐3. Although sea bream fillets fried in sunflower oil showed an increase in PUFAs, the lowest eicosapentaenoic and docosahexaenoic acid contents were found in fried samples. CONCLUSION: Sea bream fillets treated with rosemary extract showed slower oxidation than untreated fish. Neither conventional nor microwave reheating after frozen storage for 4 months had a detrimental effect on the fatty acid profile and its stability. Copyright © 2009 Society of Chemical Industry     

Effects of Four Cooking Methods on the Proximate, Mineral and Fatty Acid Composition of Fish Fillets

The effects of baking, broiling, deep frying and cooking in a microwave oven on the proximate, mineral and fatty acid composition of grouper (Epinephelus morio), red snapper (Lutjanus campechanus), Florida pompano (Trachinotus carolinus) and Spanish mackerel (Scomberomorus maculatus) were determined. The lipid content of low fat species was not significantly changed by cooking, but lipid was lost from fatty fillets during cooking. The fatty acid composition of all fillets was not significantly changed by baking, broiling or microwave cooking. Deep fried fillets absorbed the major fatty acids in the cooking medium, and as the fillet lipid content increased the extent of absorption of fatty acids from the cooking medium decreased. Sodium, potassium and magnesium levels were decreased when low fat species were cooked, but these minerals were not lost when raw fillets containing higher lipid levels were cooked. Cooking did not significantly affect the concentration of the microelements, zinc, copper, iron and manganese.     

Comparison of the effects of four cooking methods on fatty acid profiles and nutritional composition of red mullet (Mullus barbatus) muscle

This study was performed to examine the effects of different cooking methods (frying, steaming, oven cooking, and microwave cooking) on proximate chemical composition, mineral contents, and fatty acids profiles of red mullet (Mullus barbatus) fillets. The frying process caused a significant increase in fat content (from 13.37±0.04 to 34.44±0.20 g/100 g d.w.) and reduced the proportion of the palmitic acid of 50.73% and saturated fatty acids of 56.9%. While, the proportion of polyunsaturated fatty acids (PUFA) increased from 4.04% of total fatty acids for raw fillet to 49.17% of total fatty acids for fried fillets. The steamed, oven-cooked, and microwave-cooked fillets showed the best proportion of fat content, PUFA, and ω-6/ω-3 ratio as compared with fried red mullet fillets. Na, Mg, and Zn contents of cooked fish fillets significantly decreased.     

Effect of different cooking methods on vitamins,minerals and nutritional quality indices of orange-spotted grouper (<Emphasis Type="Italic">Epinephelus coioides</Emphasis>)

This study aimed to evaluate the nutritional value [proximate, fatty acid profiles, vitamins and minerals and also nutritional quality indices (NQI)] of orange-spotted grouper (Epinephelus coioides) prepared according to common consumer techniques: raw, poached, steamed, microwaved, pan-fried and deep-fried (in olive oil). There was an increase in protein, lipid and ash contents in cooked fish as compared to raw fish fillets. Cooking treatment had no significant effect on total n-3 fatty acids except for deep-fried fillets. Cooking methods had no significant effect on total n-6 fatty acids. In all the cooking methods, n-6 fatty acids were well preserved. There was no significant difference in the Mn, Zn, Ca and Fe contents of fillet between raw and cooked samples. Vitamin D content in all cooking methods did not differ significantly. None of cooking methods had a significant effect on vitamin A except for deep-frying fillets. However, vitamin B1 and B3 contents of cooked fish significantly decreased. Considering the overall nutritional quality indices, vitamin and mineral contents, steaming is the best cooking method.     

Validation of a Combi Oven Cooking Method for Preparation of Chicken Breast Meat for Quality Assessment

ABSTRACT: Quality assessment results of cooked meat can be significantly affected by sample preparation with different cooking techniques. A combi oven is a relatively new cooking technique in the U.S. market. However, there was a lack of published data about its effect on quality measurements of chicken meat. Broiler breast fillets deboned at 24‐h postmortem were cooked with one of the 3 methods to the core temperature of 80 °C. Cooking methods were evaluated based on cooking operation requirements, sensory profiles, Warner–Bratzler (WB) shear and cooking loss. Our results show that the average cooking time for the combi oven was 17 min compared with 31 min for the commercial oven method and 16 min for the hot water method. The combi oven did not result in a significant difference in the WB shear force values, although the cooking loss of the combi oven samples was significantly lower than the commercial oven and hot water samples. Sensory profiles of the combi oven samples did not significantly differ from those of the commercial oven and hot water samples. These results demonstrate that combi oven cooking did not significantly affect sensory profiles and WB shear force measurements of chicken breast muscle compared to the other 2 cooking methods. The combi oven method appears to be an acceptable alternative for preparing chicken breast fillets in a quality assessment.     

EFFECTS OF MICROWAVE COOKING ON FISH QUALITY

Changes in tenderness, unit proteolytic activity, protein denaturation and fatty acid content of trout (Onchorhyncus mykiss) cooked in microwave oven for different time-power combinations were studied and the relationship between protein denaturation and textural changes was investigated. Trout was cooked in the microwave oven at 20, 40 and 60% powers for 10, 20, 30, 40 s. As a control uncooked fish was used. Proteolysis was controlled by using microwave energy. Texture degradation due to proteolytic enzymes was reduced as microwave power increased. As cooking time and/or power of the microwave oven increased, proteolytic activity decreased which was a sign of the increase in enzyme inactivation. A correlation was found between the variation of texture and proteolytic activity (r = 0.973). It was observed that proteolytic enzymes were effective especially on myosin. Most of the fatty acids were not destroyed during microwave cooking. The optimum cooking conditions in microwave oven were determined as 60% power for 20 s of cooking time.     

Authentication of raw and cooked freeze-dried rainbow trout (Oncorhynchus mykiss) by means of near infrared spectroscopy and data fusion

This study investigated the possibility of using near infrared spectroscopy (NIRS) for the authentication of raw and cooked freeze-dried rainbow trout (Oncorhynchus mykiss) fillets. Latent variable models applied on the spectral data were developed and used to estimate proximate composition, fatty acid profile, fillet yield and cooking loss, and to classify the available dataset by the rearing farm and genetic strain of each sample.Results showed that NIR spectra can be used both to accurately estimate several chemical properties and to classify samples by rearing farm. In order to classify samples by genetic strain instead, a data fusion approach in which color and mechanical information were combined with spectral data was used. No major differences were observed between the results obtained from raw freeze-dried fillets and those obtained from cooked freeze-dried fillets, except for the estimation of certain chemical constituents of interest such as C22:6 n − 3 and polyunsaturated fatty acid content, both of which were better estimated from cooked freeze-dried fillets.     

Effects of cooking methods on the proximate,mineral and fatty acid composition of European eel (Anguilla anguilla)

The influence of microwave cooking and traditional cooking methods such as baking, grilling and frying on the nutritional composition of eels (Anguilla anguilla) was studied. All methods reduced moisture and increased the protein and fat content. Although the potassium and sodium content of fish cooked by different methods decreased significantly (P = 0.000), the calcium and magnesium content increased. The zinc content of the fish was not affected by cooking. The manganese and iron content significantly increased only in fried fish. The copper content was increased by grilling and microwave cooking. The proportion of saturated fatty acids and monounsaturated fatty acids in cooked fish decreased. Omega‐3 polyunsaturated fatty acids were increased by all cooking methods. The grilling and microwave‐cooking methods were the most suitable considering the n3/n6 ratio and eicosapentaenoic acid levels. The increase in the docosahexaenoic acid level of fried fish enhanced its nutritional value.     

Stability of Polyunsaturated Fatty Acids after Microwave Cooking of Fish

The stability of fish oils high in polyunsaturated fatty acids (PUFA) in fresh fish of low, medium and high fat content was investigated using microwave oven cooking. Cooked and uncooked portions of butterfish, mullet, mackerel and sardines were extracted, the lipid recovered and fatty acid composition determined. The effect of cooking was minimal with no detectable difference in total lipid between cooked and uncooked samples. Most important, PUFA were virtually unaffected by the overall cooking and the cooked fish retained their original PUFA composition and content.     

Lipid characteristics in cooked, chill-reheated fillets of Indo-Pacific king mackerel (Scomberomorous guttatus)

Slices of Scomberomorous guttatus cooked by four different methods (microwave cooking, grilling, steaming and shallow fat frying) were kept chilled at 5 °C for 2 days, reheated by microwave and then evaluated for the changes in the lipid characteristics. The total lipid content for raw sample was 6.0 g/100 g which consist of 49.4 g/100 g saturated (SFA), 6.9 g/100 g monounsaturated (MUFA) and 43.8 g/100 g polyunsaturated fatty acids (PUFA). Upon cooking, the total lipids changed to about 7 (microwave), 11 (grilling), 5 (steaming) and 10 g/100 g (shallow fat frying). These changes are significant, with the exception of steam cooking. Cooking did not significantly affect the percentage of NPL, PL, SFA, MUFA and PUFA in the samples. Frying resulted in the change of the SFA/PUFA ratio more than other cooking methods. A significant (P < 0.05) decrease in the content of EPA was only found in the fried samples. A significant (P < 0.05) decrease in the content of DHA in all cooked samples were also obtained. The n-6/n-3 ratio did not change significantly in all cooked and reheated samples, except for shallow fat fried. Reheating did not significantly affect the NPL and PL contents of the fillets, except for microwave cooked samples. Cooking increases the FFA, PV and TBA of samples; reheating enhances the increase.     

The comparative evaluation of the nutrient composition and sensory attributes of four vegetables cooked by different methods

The following four vegetables; beans (Phaseolus vulgaris var. vulgaris), brinjal (Solanum melongena var. esculentum), knol‐khol (Brassica oleracea var. caulorapa) and radish (Raphanus raphanistrum satvius) were processed either by conventional, pressure or microwave cooking methods and were analysed for their nutritional and sensory profile. Raw samples were used as controls. Microwave cooking resulted in greater moisture loss when compared with vegetables cooked by other methods. The protein, fat, total ash, calcium, phosphorus, iron, and dietary fibre contents of the vegetables did not differ significantly in raw or cooked vegetables. Ascorbic acid was destroyed to the greatest extent by pressure cooking followed by microwave and conventional method. The sensory attributes of cooked vegetables, as evaluated by a paired preference test, revealed that there were no significant differences between cooked radish and knol‐khol but, in the case of beans and brinjal, microwave and conventionally cooked samples were preferred over pressure cooked ones.     

Changes in lipid profiles and volatile compounds of shrimp (Penaeus vannamei) submitted to different cooking methods

Herein, the effect of three common cooking methods (boiling, baking and microwaving) on lipids and volatile compounds in shrimp (Penaeus vannamei) was assessed. The results revealed that contents of phospholipid, triglyceride, cholesterol and free fatty acids in the cooked shrimp significantly declined when compared to the raw shrimp. And these decreases occurred especially in the boiling and microwaving treatment. Among free fatty acids, the contents of palmitic acid (C_16:0), oleic acid (C_18:1n9c) and linoleic acid (C_18:2n6c) also decreased greatly in the boiled and microwaved shrimp, while EPA and DHA enhanced in each cooked group (P < 0.05). Furthermore, microwaved samples exhibited higher levels of oxidation parameters, such as acid value (AV) and thiobarbituric acid-reactive substances (TBARS). For volatile compounds, a total of 31 volatile compounds were detected by GC-IMS, and these contents increased after cooking. Aliphatic volatile compounds, including 1-octen-3-one, pentane-1-ol, 1-propanol, octanal, heptanal, pentanal and hexanal, were main flavour contributors in cooked shrimp, with higher contents observed in microwaved shrimp. In addition, the correlation analysis showed that linoleic acid was a substrate for 15 volatile compounds of cooked shrimp meat. These results indicate that microwave cooking exerts more influences on lipid profiles in shrimp and consequently caused more volatile compounds.     

Effect of Different Cooking Methods on Minerals,Vitamins, and Nutritional Quality Indices of Rainbow Trout (Oncorhynchus mykiss)

In this study, the influence of four cooking methods (baking, boiling, microwaving, and frying) on the nutritional value of rainbow trout was determined. Proximate, fatty acid composition, vitamin, mineral contents, and nutritional quality indices of rainbow trout were investigated (i.e., before and after cooking treatments). In all samples, there was reduction of total n-3 than raw fish fillets. Considering overall nutritional quality indices, vitamin, and mineral contents; baking and boiling were the best cooking methods among other methods used in this study.     

烹调方式对猪肉肌内脂肪中脂肪酸组成的影响

不同的烹调方式使猪肉中的脂肪含量和脂肪酸组成发生变化。以猪背最长肌为原料,通过4种常见的烹调方式:蒸、煮、微波、烤,探究脂肪酸的变化规律,进而指导人们的烹调方式。采用改进的Folch法提取烹调后猪肉中的脂肪,用氨丙基硅胶固相萃取小柱分离脂肪中的甘油三酯和磷脂,并采用气相色谱,以十三烷酸甲酯为内标定量分析总脂、甘油三酯及磷脂的脂肪酸组成。结果表明,与对照组相比,蒸、微波、煮和烤对猪肉脂肪中甘油三酯的脂肪酸组成无显著影响。而微波、煮和烤均使磷脂的脂肪酸组成发生显著性变化,其中饱和脂肪酸(SFA)和反式脂肪酸(TFA)的含量均显著增加,而单不饱和脂肪酸(MUFA)与多不饱和脂肪酸(PUFA)的含量明显减少,变化最明显的为烤制;蒸制对磷脂的脂肪酸组成影响最小,仅SFA和PUFA发生一定程度的变化;总脂肪酸组成差异显著,其含量变化主要是由磷脂的变化引起的。结论:烹调对磷脂影响显著;蒸制对猪肉脂肪的脂肪酸保护效果最好,烤制易破坏脂肪酸,从而降低营养价值。     

The effect of a flaxseed oil-enhanced diet on the product quality of farmed brook trout (Salvelinus fontinalis) fillets

Abstract: The effects of dietary modification with flaxseed oil‐enhanced (Flax) feed on the product quality of brook trout fillets were examined. Trout were fed a commercial feed supplemented with fish oil (CD) or flaxseed oil (Flax) for 165 d before harvesting. Proximate composition and fatty acid profile were determined on fillets. Quality parameters of the raw fillets were examined over the storage period by measuring color (L*, a*, b*), muscle pH, and thiobarbituric acid reactive substances test. Evaluations on the cooked fillets included sensory evaluation with triangle tests and a paired preference test. There were no differences in proximate composition between the groups; however, the total omega‐3 fatty acids were greater in Flax fillets (P < 0.05). Diet and day were shown to interact in their effect on whiteness, pH, and lipid oxidation (P < 0.05); however, linear regression did not determine that malondialdehyde concentration was associated with time in either diet type implying that lipid oxidation in the vacuum‐packed fish was controlled at storage temperatures (4°C). Sensory panelists were able to choose the odd sample in a replicated triangle test analyzed using the β‐binomial model, and there was preference for Flax fillets (P < 0.05). Results indicate that a Flax‐enhanced diet would have favorable effects on product quality of farmed brook trout.     

Effect of Cooking Rates in Electric or Microwave Oven on Cooking Losses and Retention of Thiamin in Broilers

A study was conducted to determine the effect of two microwave oven and two electric oven cooking rates on retention of thiamin and cooking losses with broiler chickens. Thiamin was determined by a microbiological turbidimetric assay of raw and cooked meats. Broilers cooked in the microwave oven retained more thiamin than broilers cooked in the electric oven. There was no difference in thiamin retention between broilers cooked in the microwave oven at 800 and 1600 watts. Broilers cooked in the electric oven at 204°C retained more thiamin than broilers cooked at 121°C. Broilers cooked in a 1600 watt microwave oven had the greatest weight loss. No difference in weight loss occurred between broilers cooked in an 800 watt, 121°C or 204°C oven.     

Effect of Various Processing Methods on the Physical Properties of Cooked Rice and on in vitro Starch Hydrolysis and Blood Glucose Response in Rats

The effects of various cooking methods on the physical and structural properties cooked rice, on the in vitro hydrolysis of the contained starch and on blood glucose response in rats were investigated. At optimum cooking state, a larger filamentous network was formed and most of the starch granules were fragmented, furthermore the samples heated by microwave and electric cooker showed a more compact structure compared to those treated in an autoclave or stone pot. The highest degree of gelatinization (DG) was observed in the sample treated in an autoclave (75.2%), followed by stone pot (71.1%), electric cooker (66.9%) and microwave oven (64.6%). The highest firmness (3.49 N) was observed in cooked rice heated by microwaves and no significant differences (p > 0.05) were found between the other samples. All cooked rice samples showed increased pasting temperatures and decreased peak viscosity compared to those of raw rice flour. The starch hydrolysis rates and their kinetic constants of cooked rice samples increased with increase in DG, and relatively higher values were observed in samples treated in the autoclave and stone pot. There was a significant difference in the blood glucose content depending on cooking methods, and the highest glucose level was observed in the sample heated by autoclaving.     

CHOLESTEROL AND PROXIMATE COMPOSITION OF CHANNEL CATFISH (ICTALURUS PUNCTATUS) FILLETS – CHANGES FOLLOWING COOKING BY MICROWAVE HEATING, DEEP-FAT FRYING, AND OVEN BAKING

Effects of microwave heating, deep-fat frying, and conventional oven baking on proximate composition and concentration of cholesterol in channel catfish fillets were examined. The paired fillet technique was employed to control the variability among fish. A total of fifteen catfish were randomly assigned to the three cooking methods. All cooking procedures resulted in moisture loss. Fillets that were deep-fat fried showed the lowest moisture content but the highest fat content, respectively, among three cooking methods. The three cooking methods, on a dry weight basis, all significantly affected cholesterol concentration of cooked catfish compared with raw fillets. Deep-fat frying resulted in a significant decrease of cholesterol and showed the lowest concentration of cholesterol among three cooking methods probably due to leaching of cholesterol into frying oil.