Antioxidative activity of α-tocopherol in cooked and uncooked ground pork

The effect of α-tocopherol (0, 100, 200 ppm) on lipid oxidation either in cooked or uncooked ground pork was studied during aerobic storage at 4°C and -20°C. Lipid oxidation was measured using the 2-thiobarbituric acid (TBA) method and rancidity development was scored by a trained sensory panel. Alpha-tocopherol slowed the rate of oxidation in cooked ground pork stored at either 4°C or -20°C and uncooked samples refrigerated for extended periods of time (12 days). In cooked product stored at 4°C where oxidation development was intense and off-flavors were strong, panelists did not detect flavor differences due to treatments. But in cooked product stored at -20°C sensory results were consistent with TBA analysis. Pre-rigor grinding, known to induce a high pH and inhibit lipid oxidation in uncooked fresh pork, had no protective effect on lipid oxidation as measured by TBA values in cooked ground pork, regardless of storage condition. TBA numbers increased during storage of cooked product at 4°C with an increase in internal cooking temperature between 50°C and 80°C. Internal cooking temperatures of 70°C or higher induced a rapid rate of oxidation when stored at 4°C.     

Effect of cooking on the formation of N-nitrosodimethylamine in Korean dried seafood products

Only N-nitrosodimethylamine (NDMA) was detected when N-nitrosamines (NA) were analysed in seven dried seafood products, either uncooked or cooked. The cooking methods used were a briquet fire, a gas range, an electric oven, a microwave oven, a steam cooker and an electric coil cooker. The contents of NDMA ranged from 1.0 to 46.9 μg kg^-1 in uncooked products. When these samples were cooked, regardless of the cooking method, the content of NDMA tended to increase, ranging from 1.1 to 630.5 μg kg^-1. In general, indirect heating such as a steam cooker and a microwave oven, as compared with direct heating such as a gas range and a briquet fire, caused less increase in NDMA during cooking.     

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.     

Effect of Natural Antioxidants,Irradiation, and Cooking on Lipid Oxidation in Refrigerated,Salted Ground Beef Patties

Antioxidant effects of natural antioxidants in 73%‐lean ground beef patties during refrigeration were studied. Samples were subject to an antioxidant treatment (pomegranate extract, grape seed extract, butylated hydroxyanisole, or no treatment) and an irradiation treatment (0 or 1.5 kGy) before being evaluated for both uncooked and cooked indicators of lipid oxidation. Chemical evaluation of antioxidant activity were determined over 9 d through measurement of thiobarbituric reactive substances values. Physical evaluation of antioxidant activity was monitored by changes in physical color and sensory odor analysis on patties before and after cooking. Butylated hydroxyanisole extended the induction period of oxidation in all unirradiated beef patties better than the natural antioxidants. Panelists were able to distinguish a difference (in terms of oxidation attributes) between patty samples of different antioxidant and irradiation treatments while samples were uncooked, but unable to distinguish a difference between patties after cooking.     

Hot air drying of cooked and uncooked tarhana dough, a wheat flour-yoghurt mixture

Drying behaviour of cooked (CTD) and uncooked tarhana dough (UTD) slabs (1, 3 and 6 mm) were determined at constant air temperature (80 °C) and velocity (1.86 m/s). Both samples dried in the falling rate period. An analysis of variance (ANOVA) revealed that slab thickness and cooking process significantly affected the drying rate. The effective moisture diffusivity values of CTD and UTD samples were determined from drying experiments using Fick's diffusion model. Effective diffusivity was higher in cooked sample than in uncooked one (1.3-23.5᎒^-10 and 0.99-10.0᎒^-10 m²/s, respectively). This was attributed to the development of channels and pore structure during starch gelatinisation in the cooked sample.     

枣干和米饭-枣混合餐餐后血糖反应

为研究烹调前后枣干及枣干配合粳米食用的餐后血糖反应,选择粳米饭、枣干、蒸枣、炖枣、枣＋米饭、枣米饭和枣米粥为研究对象,测定了11 名健康女性受试者食用上述所有样品餐后240 min的血糖反应和枣干烹调前后的质构指标,并计算血糖指数（glycemic index,GI）及血糖反应特征值。结果表明：几种烹调方式中,炖制对枣干的质构影响最大。枣干、蒸枣和炖枣的GI分别为56、65和56,其中炖枣的血糖曲线波动和血糖曲线下负面积最大。米饭、枣＋米饭、枣米饭、枣米粥的GI分别为78、75、82和85。需要控制血糖者可在替代高GI碳水化合物食物的前提下少量食用未烹调的枣干,但不宜食用烹调后的枣;烹调后食物混合餐的GI需实际测定,若根据公式将混合餐中各组分的GI按比例简单加和,会引起一定误差。     

Ohmic heating for cooking rice: Electrical conductivity measurements,textural quality determination and energy analysis

In this study, an innovative technique, namely ohmic heating was applied in rice cooking and compared with conventional method using electric rice cooker. Four types of rice samples including white rice of two varieties (KDML105 and Sao Hai), brown rice and germinated brown rice of one variety (KDML105) were used. Electrical conductivities of mixtures between rice samples and 0.1 M salt solution at various ratios were measured. Empirical models were developed for predicting electrical conductivities of rice samples as a function of temperatures. Textural properties of cooked rice samples and energy consumption were compared between ohmic and conventional cooking methods. The purposes of this work were to (1) study the possibility of applying ohmic method in rice cooking and (2) compare between cooking rice by ohmic and conventional method. The results revealed that it is possible to apply ohmic method for cooking all rice samples by using 0.1 M salt solution in the mixtures. The electrical conductivities of white rice (KDML105), white rice (Sao Hai), brown rice and germinated brown rice (KDML105) mixtures were 0.246–0.900, 0.375–1.005, 0.617–1.370 and 0.485–1.182 S/m respectively. The rice cooked by ohmic method had significantly different textural properties from that cooked by electric rice cooker. The magnitude of difference depended on the rice types. The electrical energy consumption of ohmic cooking system was approximately 73–90% of energy required for conventional rice cooker.     

Prediction of technological quality (cooking loss and Napole Yield) of pork based on fresh meat characteristics

In order to investigate if cooking loss and Napole Yield can be predicted from various fresh meat characteristics, pH (1, 15, 30, 60, 120 min and 24 h post mortem), temperature (1, 15, 30, 60, 120 min and 24 h post mortem), water-holding capacity (Honikel's drip loss method and centrifugation loss), and NMR T2 relaxation 24 h post mortem were measured in fresh porcine M. longissimus dorsi from 102 Hampshire crossbreeds of known RN(-) genotype. Subsequently, cooking loss and Napole Yield were determined on cooked and cured, cooked samples, respectively, and partial least squares regression (PLS) was carried out to investigate possible intercorrelations between the physico-chemical measurements performed on the fresh meat and cooking loss/Napole Yield. Significant correlations were found between NMR T2 relaxation measured in fresh pork 24 h post mortem and the cooking loss (R=0.64) and Napole Yield (R=0.58), whereas no correlations were found between traditionally applied methods such as pH measurements, Honikel's method and centrifugation, and the cooking loss/Napole Yield. Consequently, it is concluded that NMR T2 relaxation characteristics of fresh pork in contrast to traditional fresh meat characteristics contain information about factors of importance for cooking loss/Napole Yield from cooked uncured/cured pork. The result implies that low-field (LF) NMR data from fresh meat reflects information about water compartmentalisation and mobility that is partly decisive for subsequent heat-induced changes of importance for the distribution of water within the cooked meat. In addition, the obtained results show that LF NMR data measured on fresh meat also seems to contain information about the inherent water of importance for the technological characteristics of the meat even when the meat is cured before cooking.     

Lipid Oxidation in Ground Beef Patties as Affected by Time-Temperature and Product Packaging Parameters

Oxidative rancidity in fresh and stored ground beef samples was measured using a thiobarbituric acid (TBA) assay with antioxidant protection. The independent variables were fat concentration (15 or 30%), package type (polyethylene or vacuum-packaged), freezer storage temperature (-12.2°, -23.3° or -34.4°C) and storage time (4, 8, 12, 16, or 20 weeks). At the end of each storage time samples were thawed and TBA values were determined on the samples before and after cooking. TBA values increased during the first 12 to 16 weeks after which time it decreased for both the cooked and uncooked samples. The higher fat samples, packaged in polyethylene, had higher TBA values for both cooked and uncooked patties. Uncooked patties stored at - 12.2°C had higher TBA values than those stored at -23.3°C or -34.4°C but cooked sample TBA values showed no dependence on storage temperature.     

Effect of Opuntia pulp as a clean label ingredient on techno-functional properties of meat-free burger

There is a universal increase from an animal-based diet towards healthy plant-based foods. Opuntia fruit pulp (OFP) as a pigment/hydrocolloid complex provides excellent functional properties. The aim of this study was the reformulation of the meat-free burgers by using OFP (0.5, 1.5 and 2.5%) as a stabilised natural pigment and analysing techno-functional characteristics of uncooked and cooked meat-free burgers. The OFP was a rich source of polyphenols (35.3 ± 2.07 mgGAE/g) and carbohydrates (68.22 ± 0.5%). All uncooked treated burgers exhibited higher water-holding capacity and redness as well as lower thiobarbituric acid reactive substance (TBARS) values. Results confirmed a higher cooking loss in the control sample (22.2 ± 0.63%) compared with the OFP-treated burger at 1.5 and 2.5% content. Incorporation of OFP as a great source of natural pigments and phenolic components had considerably influenced cooking yield, moisture retention, juiciness and oxidative stability of meat-free burgers. The lowest total colour difference value with resemble meat burger was observed in the treated burgers at the highest content of OFP. According to sensory evaluation, the overall acceptability of cooked burgers with 1.5% OFP was more satisfactory than other samples. Using this clean label ingredient provides a sustainable burger, which is beneficial to the public health, environment and animal welfare.     

A PRESSING-DEVICE TO MEASURE THE TEXTURE OF COOKED RICE

Cooked rice held between glass plates was pressed by dropping a 2.5 kg load from a predetermined height. A significant variation (1.90 to 3.45 cm²) in the pressed area for raw cooked samples was found. Cooking methods exerted a significant influence on the pressed area. The pressed area of the cooked rice and the L/B ratio of uncooked samples correlated positively. This test significantly differentiated parboiled rices. The pressed area correlated negatively with the temperature of parboiling. Besides the varieties, the cooking methods and the testing time significantly influenced the pressed area of parboiled samples, thus indicating the reliability of this test even under varying testing conditions.     

Cooking temperature effects on the forms of iron and levels of several other compounds in beef semitendinosus muscle

The influence of final cooked temperature on the form of iron present and on the concentration of taurine, carnosine, coenzyme Q(10) and creatine was investigated in surface and inner parts of 30-mm thick steaks from beef semitendinosus muscle (n=6). The use of a fast, dry-heat cooking method with a Silex clam cooker (set at 200 °C) led to cooking times ranging from 5.6 to 8.6 min for final internal temperatures of 60 and 85 °C, respectively. The proportion of iron as soluble haem iron decreased from 65% in uncooked meat to 22% when cooked to 60 °C and then decreased more gradually with increases in final cooked temperature. The proportion of insoluble haem iron increased in a reciprocal manner, while changes in the proportions of soluble and insoluble non-haem iron were relatively small, but increases in the percentage of insoluble non-haem iron with increasing final temperature were significant (P<0.01). Changes in the forms of iron with cooking generally took place more rapidly in surface samples than inner samples. On a dry-matter basis, concentrations of taurine, carnosine, coenzyme Q(10), and creatine all decreased with cooking, but the decreases were greatest for taurine and creatine. Losses of creatine were at least partly due to conversion to creatinine, and, along with the other compounds, probably included some loss in cooking juices. It is concluded that despite these changes with cooking, beef semitendinosus muscle remains a good source of iron and a useful source of the potentially bioactive compounds taurine, carnosine, coenzyme Q(10) and creatine.     

Change in proximate, amino acid and fatty acid contents in muscle tissue of rainbow trout (Oncorhynchus mykiss) after cooking

Changes in proximate, amino acid and fatty acid composition of farmed, commercially important rainbow trout (Oncorhynchus mykiss) after conventional and microwave cooking were analysed. Rainbow trouts cooked in microwave ovens had statistically significant higher total protein, total fat, and ash than electrical oven‐cooked samples. The amounts of essential and nonessential amino acids were not different between cooking methods, but the difference between raw and cooked samples was significant. Lysine, leusine, methionine, threonine, valine, arginine and histidine were found most in microwave‐cooked rainbow trouts whereas isoleucine, tyrosine and phenylalanine were found most in electrical oven‐cooked samples. As total saturated fatty acid and total monounsaturated fatty acids amount were not statistically different between the cooking methods, the difference between raw and cooked fillets was found statistically significant (P < 0.05). There was no statistically significant difference between raw and cooked fillets in total n‐3 and n‐6 contents.     

Effect of cooking procedures on tylosin residues in chicken meatball

Most information about drug residues is related to their concentrations in raw products. The objective of this study was to assess the effects of various microwave and boiling treatments on the stability of different concentrations of tylosin in chicken meatballs. The chicken meatball samples (75 g) were prepared and fortified by 3 concentrations of tylosin (100, 200 and 300 μg kg^?1) and were cooked by boiling (100 °C for 10, 20, 30 min) and microwave procedure (power 450 W for 1, 1.5 and 2 min). The tylosin content was measured in raw and cooked samples through the use of high performance liquid chromatography. The microwave and the boiling process significantly reduced the tylosin. In both procedures, there were negative correlations between the length of cooking time and the reduction percentage of tylosin. In addition, tylosin reduction percentage in chicken meatball cooked by boiling depended on its concentration in uncooked samples. There was a relationship between tylosin reduction percentage and the increase in the internal temperature and weight loss during the cooking process. The results of this study indicate that tylosin residues in the food are decreased during the cooking process. Thus, given that a food product is cooked to be consumed, the surveillance of data obtained from tylosin measurement in the raw tissues samples could not be considered as consumers’ exposure to tylosin via dietary intake.     

Structuring and texturing gluten-free pasta: egg albumen or whey proteins?

The effects of adding egg albumen or whey proteins to pasta made from parboiled rice flour (PR) were investigated. Pasta quality was evaluated in terms of color, furosine content, and cooking properties (water absorption, cooking loss, and consistency at the optimal cooking time). The surface heterogeneity of the cooked and uncooked materials was studied, and some starch properties (pasting properties and starch susceptibility to α-amylase hydrolysis) were assessed, along with the features of the protein network as determined by conditional solubility studies and with ultrastructural features of the cooked products. Egg albumen improved pasta appearance and gave a product with low cooking loss, firmer, and nutritionally more valuable than the other ones. In albumen-enriched pasta, small starch granules appear homogeneously surrounded by a protein network. In the uncooked product, the protein network is stabilized mostly by hydrophobic interactions, but additional disulfide interprotein bonds form upon cooking. Thus, addition of 15 % liquid albumen to PR results in significant improvement of the textural and structural features of rice-based gluten-free pasta.     

EFFECTS OF END-POINT TEMPERATURE AND FAT LEVEL ON THE RESIDUAL CHOLESTEROL IN GROUND BEEF PATTIES1

Patties of lean ground beef with 2% fat (L2PF) and 6% fat (L6PF) were used to study the fat and cholesterol composition of raw and cooked ground beef and to determine how the end-point cooking temperature affects the amount of fat and cholesterol in a lean ground beef patty as it would be eaten by the consumer. The two patty types were obtained from the longissimus muscle of steers with marbling scores associated with “Standard” to “Select” and “Select” to “Choice” U.S. carcass grades of beef, respectively. All steers were fed a diet of roughage and concentrates to ensure fat deposition over the 12th and 13th ribs; longissimus muscles between the 7th and 10th ribs were removed, trimmed of all external fat, ground and formed into three 130-g patties. One patty was fried to an internal temperature of 60C, another to 71C and the third was uncooked. After frying, the patties were measured for drip loss, moisture and total fat. The fat extract was used for cholesterol analysis. The cooked L2PF sample had significantly less fat than the cooked L6PF samples, but there was no difference between the L2PF and L6PF in cholesterol. End-point temperature had no effect on the fat and cholesterol contents for either L2PF or L6PF samples, but the higher end-point temperature resulted in a significant loss of moisture.     

The effects on colour, texture and sensory attributes achieved by washing black tilapia flesh with a banana leaf ash solution

Summary The washing of freshwater fish with clarified solutions of banana leaf ash to remove the muddy odour and flavour is common both in Bangladesh and Indian households. However, no scientific study has been done to evaluate its effectiveness. This study was, therefore, done to show the effect of the washing treatments on the following sensory attributes: odour; flavour; colour and texture. The latter two attributes were also measured by instrumental methods. The experimental animal was black tilapia ( Oreochromis mossambicus ), which was filleted and each fillet washed by a clarified solution of banana ash (either originally 5 or 7% ash). Controls were fillets washed in ice-slush only. Those fillets washed in 5% ash for 5 min were the most acceptable for eating, cooked or uncooked. There were highly significant differences ( p  < 0.01) in the L-colour values (lightness values) when treated fillets were compared to untreated fillets. However cooking the fillets reduced the difference, making it not significant. Texture was significantly affected by washing and this was retained in cooked fillets, however this was particularly significant using a 7% solution which gave a softer fillet.     

Variation in the Vitamin and Mineral Content of Raw and Cooked Commercial Phaseolus Vulgaris Classes

Raw and cooked samples of nine different commercial classes of the Phaseolus vulgaris L. species were analyzed for their contents of five water-soluble vitamins and nine minerals. On a 100g dry weight basis, the mean vitamin and mineral values of the raw bean samples amounted to the following: thiamin 0.99 mg, riboflavin 0.20 mg, niacin 1.99 mg, vitamin B₆ 0.49 mg, folic acid 0.30 mg, phosphorus 0.46g, sodium 10.3 mg, potassium 1.54g, calcium 0.15g, magnesium 0.20g, zinc 3.2 mg, manganese 1.4 mg, copper 0.91 mg, and iron 5.84 mg. With a few exceptions variabilities of these nutrients between bean classes exceeded those within classes. Nutrient variabilities in cooked samples, again with a few exceptions, were higher than in the corresponding uncooked material. Retention values of water-soluble vitamins during cooking between bean classes averaged between 70 and 75%. Retention of minerals during cooking ranged from a low of 38.5% for sodium to total retention for calcium, with the majority of the minerals falling into the 80–90% level.     

Cryoprotectant Effects in Surimi and Surimi/Mince-based Extruded Products

The relative cryoprotective effects of liquid sorbitol (L) alone and in combination with sucrose (L-S) was assessed in surimi, extruded uncooked and cooked products, and compared with the cryoprotective effects of crystalline sorbitol (C), liquid polyol (P), and modified starch (MS). Variables evaluated included gel-forming properties, cooking loss, drip loss and ice crystal formation. Addition of 8% sorbitol resulted in best water-holding ability, gel strength and least ice crystal formation. A better cryoprotective effect was shown in uncooked than in cooked products. No significant differences in effectiveness were found among C, C-S, L and L-S. Optimum sweetness was obtained with either C and L at 8% or L-S at 3:3%. Both C-S and L-S at 4:4% were judged to be slightly too sweet.     

Effects of Inorganic Phosphates and Sodium Hydroxide on the Cooked Cured Color, pH and Emulsion Stability of Reduced-Sodium and Conventional Meat Emulsions

Phosphates that increased meat emulsion stability the most also caused the highest decrease in cured color development. The addition of 0.125% sodium hydroxide also reduced cured color development. Holding uncooked emulsions, containing either sodium tripolyphosphate or tetrasodium pyrophosphate, up to 60 min after emulsion preparation plus adding tetrasodium pyrophosphate later in the emulsification procedure improved cured color development upon cooking. In both cases, cooked pH increased as cured color improved, and emulsion stability declined. This suggested that phosphate effects other than, or in addition to, pH were involved in cured color development and emulsion stability.