不同烹饪加工豇豆在冷藏过程中亚硝酸盐含量及抗氧化性能的变化

研究了水煮、蒸和油炸3种烹饪加工豇豆在4℃冷藏过程中亚硝酸盐含量及抗氧化性能的变化。采用福林酚法和TEAC法分别测定了不同烹饪加工豇豆提取物的多酚含量和抗氧化能力。结果表明:烹饪加工豇豆的亚硝酸盐含量显著高于新鲜豇豆;在冷藏过程中亚硝酸盐含量均先升后降,在贮藏第3天时,含量最高。在整个贮藏过程中,水煮豇豆的亚硝酸盐含量均显著高于其他组的。豇豆经烹饪加工后,其游离酚含量显著下降,其中油炸豇豆下降最显著,蒸豇豆下降最少。经蒸和油炸后豇豆的结合酚含量显著增加,其中油炸后增加的量更多,而水煮后结合酚含量则显著下降。随着贮藏时间的延长,不同烹饪加工豇豆的游离酚含量均显示出先增加后下降的趋势,而结合酚含量则显著下降。总抗氧化能力与多酚含量变化趋势比较相似,它们之间存在高度相关性。     

Effect of soaking,germination, cooking and fermentation on antinutritional factors in cowpeas

The present work deals with the study of efficacy of some treatments, namely soaking (in water and bicarbonate solution( ordinary and pressure cooking, germination and fermentation in reducing or removal of antinutritional factors usually present in cowpeas (protease inhibitors, tannins, phytic acid and flatus‐producing oligosaccharides (raffinose and stachyose). The results showed that long‐time soaking (16 h) in bicarbonate solution caused remarkable reduction in the antinutritional factors. Pressure cooking was more effective than ordinary. Cooking pregerminated cowpeas was most effective. Fermentation completely removed trypsin inhibitor, oligosaccharides and reduced remarkably phytic acid. However, tannins noticeably increased.     

Effect of soaking,germination, cooking and fermentation on antinutritional factors in cowpeas

The present work deals with the study of efficacy of some treatments, namely soaking (in water and bicarbonate solution), ordinary and pressure cooking, germination and fermentation in reducing or removal of antinutritional factors usually present in cowpeas (protease inhibitors, tannins, phytic acid and flatus-producing oligosaccharides (raffinose and stachyose). The results showed that long-time soaking (16 h) in bicarbonate solution caused remarkable reduction in the antinutritional factors. Pressure cooking was more effective than ordinary. Cooking pregerminated cowpeas was most effective. Fermentation completely removed trypsin inhibitor, oligosaccharides and reduced remarkably phytic acid. However, tannins noticeably increased.     

蒸煮助剂对稻麦草亚硫酸钾蒸煮的作用

研究了新型蒸煮助剂磷酸钾和常规蒸煮助剂蒽醌、CT-1在稻麦草的亚硫酸钾蒸煮中的作用.实验结果表明磷酸钾对稻草和麦草亚硫酸钾蒸煮具有不同程度降低纸浆硬度的作用.蒽醌对于麦草亚硫酸钾法蒸煮有显著作用.而蒽醌和CT-1对于稻草亚硫酸钾法蒸煮没有起到明显作用.     

大豆蒸煮时间对黄豆酱发酵过程中理化特性的影响

研究了不同蒸煮时间(5、8、10、15 min)对黄豆酱发酵过程理化指标和感官特性的影响,分析不同黄豆酱的总氮(酱醪除外)、氨基酸态氮、可溶性氮含量的动态变化,豆粒硬度变化以及产品感官品质。结果表明,黄豆酱发酵前期(1~30 d),总氮、氨基酸态氮、水溶性氮含量均随培养时间的延长呈上升趋势,之后基本保持动态平衡或稍有变化。蒸煮时间对黄豆酱各指标的影响有显著性差异(p<0.05),其中对酱醪的影响尤为显著。蒸煮时间对豆粒的硬度影响比较大,蒸煮时间越长,豆粒硬度越小,发酵至30 d时,蒸煮15 min黄豆酱中豆粒破坏严重。对四种不同产品进行感官评价,发现蒸煮8 min黄豆酱产品无论在色泽、香气、滋味和体态各方面较好,总体得分最高。      

Influence of amylose content on cooking time and textural properties of white salted noodles

White salted noodles were prepared from reconstituted flours of various amylose content to determine the effects of amylose content on noodle dough properties and texture of noodles cooked for optimum cooking time. With decrease of amylose content from 26.5 to 3. 0%, optimum water absorption of noodle dough increased from 39 to 49% and cooking time of noodles decreased from 16 to 7 min. Hardness of cooked noodles prepared from reconstituted flour consistently decreased with increase in proportion of waxy starch. Noodles less than 12.4% amylose content exhibited higher springiness and cohesiveness than noodles greater than 17.1% amylose content. Cohesiveness and springiness of noodles prepared with partial waxy starches, of which amylose content ranged from 16. 6 to 22. 7%, were comparable to those of noodles prepared from <12. 4% amylose content. Amylose content of starch was significantly correlated with hardness, springiness, and cohesiveness of cooked noodles prepared from reconstituted flours.     

Effect of sodium hexametaphosphate concentration and cooking time on the physicochemical properties of pasteurized process cheese

Sodium hexametaphosphate (SHMP) is commonly used as an emulsifying salt (ES) in process cheese, although rarely as the sole ES. It appears that no published studies exist on the effect of SHMP concentration on the properties of process cheese when pH is kept constant; pH is well known to affect process cheese functionality. The detailed interactions between the added phosphate, casein (CN), and indigenous Ca phosphate are poorly understood. We studied the effect of the concentration of SHMP (0.25-2.75%) and holding time (0-20 min) on the textural and rheological properties of pasteurized process Cheddar cheese using a central composite rotatable design. All cheeses were adjusted to pH 5.6. The meltability of process cheese (as indicated by the decrease in loss tangent parameter from small amplitude oscillatory rheology, degree of flow, and melt area from the Schreiber test) decreased with an increase in the concentration of SHMP. Holding time also led to a slight reduction in meltability. Hardness of process cheese increased as the concentration of SHMP increased. Acid-base titration curves indicated that the buffering peak at pH 4.8, which is attributable to residual colloidal Ca phosphate, was shifted to lower pH values with increasing concentration of SHMP. The insoluble Ca and total and insoluble P contents increased as concentration of SHMP increased. The proportion of insoluble P as a percentage of total (indigenous and added) P decreased with an increase in ES concentration because of some of the (added) SHMP formed soluble salts. The results of this study suggest that SHMP chelated the residual colloidal Ca phosphate content and dispersed CN; the newly formed Ca-phosphate complex remained trapped within the process cheese matrix, probably by cross-linking CN. Increasing the concentration of SHMP helped to improve fat emulsification and CN dispersion during cooking, both of which probably helped to reinforce the structure of process cheese.     

Effect of trisodium citrate concentration and cooking time on the physicochemical properties of pasteurized process cheese

The effects of the concentration of trisodium citrate (TSC) emulsifying salt (0.25 to 2.75%) and holding time (0 to 20 min) on the textural, rheological, and microstructural properties of pasteurized process Cheddar cheese were studied using a central composite rotatable design. The loss tangent parameter (from small amplitude oscillatory rheology), extent of flow (derived from the University of Wisconsin Meltprofiler), and melt area (from the Schreiber test) all indicated that the meltability of process cheese decreased with increased concentration of TSC and that holding time led to a slight reduction in meltability. Hardness increased as the concentration of TSC increased. Fluorescence micrographs indicated that the size of fat droplets decreased with an increase in the concentration of TSC and with longer holding times. Acid-base titration curves indicated that the buffering peak at pH 4.8, which is due to residual colloidal calcium phosphate, decreased as the concentration of TSC increased. The soluble phosphate content increased as concentration of TSC increased. However, the insoluble Ca decreased with increasing concentration of TSC. The results of this study suggest that TSC chelated Ca from colloidal calcium phosphate and dispersed casein; the citrate-Ca complex remained trapped within the process cheese matrix. Increasing the concentration of TSC helped to improve fat emulsification and casein dispersion during cooking, both of which probably helped to reinforce the structure of process cheese.     

The effect of the pH at cooking on the properties of processed cheese spreads containing whey proteins

Processed cheese spreads were made with and without whey proteins under varying cooking pH conditions. The processed cheeses were cooked at one pH value and at the end of the cooking process the pH was adjusted to the final product pH of 5.7. The rheological properties and whey protein denaturation levels of the processed cheese spreads were measured. The rheological properties and texture of the processed cheeses containing whey proteins could be markedly modified by varying the cooking pH during processing, whereas those without whey proteins were unaffected. These textural modifications could not be explained solely by the changes in whey protein denaturation during cooking. It is proposed that the interactions of the whey proteins during cooking affect the processed cheese texture, and that these interactions are affected by the pH of the processed cheese during processing.     

The effect of drying conditions on the development of the hard-to-cook defect in steam-treated cowpeas

A three‐factor–three‐level Box–Behnken design was used to evaluate the effect of drying time, temperature and humidity on textural and physicochemical characteristics during storage of steamed cowpeas. The treatment significantly improved cooked texture and prevented hardening during storage under severe conditions (42 °C/80% relative humidity, RH). Before storage, the cooked texture of treated samples was between 535–628 and 602 N for the untreated control, and between 516–649 and 1394 N after storage at 42 °C/80% RH. The peak force of stored cowpeas significantly decreased as the drying temperature increased. Steaming and drying reduced phytase activity to 59–64% of the original activity and decreased phytate content from 0.133% to 0.074–0.105%. Drying time had a significant effect on phytase activity whereas all drying parameters significantly affected phytate concentration and water absorption. The drying conditions applied after steaming significantly influences seed characteristics; therefore, selection of optimum drying conditions may be used to control seed quality, especially texture.     

The effect of cooking on the phytochemical content of vegetables

Cooking induces many chemical and physical modifications in foods; among these the phytochemical content can change. Many authors have studied variations in vegetable nutrients after cooking, and great variability in the data has been reported. In this review more than 100 articles from indexed scientific journals were considered in order to assess the effect of cooking on different phytochemical classes. Changes in phytochemicals upon cooking may result from two opposite phenomena: (1) thermal degradation, which reduces their concentration, and (2) a matrix softening effect, which increases the extractability of phytochemicals, resulting in a higher concentration with respect to the raw material. The final effect of cooking on phytochemical concentration depends on the processing parameters, the structure of food matrix, and the chemical nature of the specific compound. Looking at the different cooking procedures it can be concluded that steaming will ensure better preservation/extraction yield of phenols and glucosinolates than do other cooking methods: steamed tissues are not in direct contact with the cooking material (water or oil) so leaching of soluble compounds into water is minimised and, at the same time, thermal degradation is limited. Carotenoids showed a different behaviour; a positive effect on extraction and the solubilisation of carotenes were reported after severe processing. © 2013 Society of Chemical Industry     

香味调料在烹饪中的作用

烹饪加工中常需加香味调料,用以改善或增加菜点的香气,或掩盖原料中的不良气味。烹饪中使用的都是植物性天然香味调料。不同的香味调料使用的民有所不同,所用形态也有所差异。使用香味调料时应根据不同的 同的质量要求和工艺过程来选择,以求获得最佳的风味效果。     

The effect of pod and seed positions on the physical and cooking properties of faba beans (Vicia faba)

The effect of pod location on plant (lower, middle and upper regions) and seed position inside the pods (nodular, middle and terminal) on certain characteristics of dry and stewed faba beans were studied. The weight, volume, relative density, seed coat (%), hydration and swelling coefficients were determined for dry seeds. Hydration and swelling coefficients, fractured beans (%), penetrometer readings and scores of colour, granulation and softness (by taste panel) were evaluated for stewed beans. The weight, volume, relative density, pH, and total and soluble solids content of the stewed liquor were also measured. Analysis of variance showed that the weight and volume of 1000 dry seeds were significantly (P<0.001) affected by pod location and seed position. Higher values were obtained for lower pods and terminal and middle seeds. Seeds from upper pods had the highest percentage of seed coat. Pod location showed a significant effect on the weight, volume, pH, soluble and insoluble solids of stewed liquor. No significant effect was found for pod location or seed positions on the characteristics of stewed beans, except the hydration coefficient which was significantly affected by pod location.     

A study of the relationship between the mechanical properties and the sensorial optimal cooking time of spaghetti

This study investigated the relationship between the mechanical properties and the sensorial optimal cooking time (OCT) of spaghetti. Three semolina spaghetti samples with an increasing radius and three non-conventional spaghetti samples (one wholemeal semolina and two maize-based spaghetti) were analyzed. Tenacity, elongation at break and phase shift angle (tan delta) were monitored during the cooking and overcooking of spaghetti using a dynamic mechanical analyzer. The sensorial OCT was also determined by a trained panel. Results highlight that the mechanical parameters are related with the OCT for all investigated spaghetti samples. In particular, a relationship was observed with elongation at break and tan delta.     

The effect of cooking conditions on the eating quality of pork

Two experiments were conducted to examine the effects of cooking parameters, including final internal temperature (65, 72·5 or 80°C), on the eating quality of pork. Assessments were made by a 10-member trained taste panel. In Experiment 1 on loin steaks (m. longissimus) from 28 carcasses weighing 66 ± 1·9 (SD) kg, increasing the final internal temperature from 65 to 80°C had the following effects on mean scores (1-8): tenderness -1·0; juiciness -1·5, pork flavour +0·6 and abnormal flavour -0·5. The medium temperature of 72·5°C was suggested as ideal. In Experiment 2 on leg roasts (m. gluteobiceps) from 96 carcasses weighing 65 + 2·7 (SD) kg, increasing the final internal temperature from 65 to 80°C had the following effects on mean scores (1-8): tenderness -0·2 (not significant), juiciness -0·6, pork flavour +0·3 and abnormal flavour -0·5. The effects of final internal temperature were therefore smaller in roasts and temperatures towards the upper end of the range would be recommended for ideal eating quality, balancing small losses in tenderness and juiciness against gains in flavour scores. Although the experiments were not designed to examine source and sex effects there was evidence that tenderness can be improved through the use of Duroc genes and pelvic suspension of carcasses and no evidence of differences in eating quality between entire males and females.     

The effect of cooking on Brassica vegetables

Assessing antioxidant intake requires a food antioxidant database. However, cooking may affect antioxidant content due to antioxidant release, destruction or creation of redox-active metabolites. Here, effects of boiling, steaming and microwaving of broccoli, cauliflower, cabbage and choy-sum (Chinese cabbage) were explored by measuring antioxidant contents of raw and cooked vegetables. Cooking water was also tested. For all cooked vegetables, antioxidant content was highest in steamed > boiled > microwaved, and decreased with longer cooking time, regardless of method. All steamed vegetables had higher antioxidant contents than had matching raw vegetables. Effects were variable for boiling and microwaving. Microwaving caused greater antioxidant loss into cooking water than did boiling. Marked losses of anitoxidants occurred in microwaved cabbage and spinach. To assess food antioxidant content/intake accurately, cooking effects need detailed study. Steaming may be the cooking method of choice to release/conserve antioxidants. The cooking water is a potentially rich source of dietary antioxidants.     

Enzymatic changes in pectic polysaccharides related to the beneficial effect of soaking on bean cooking time

BACKGROUND: Cooking time decreases when beans are soaked first. However, the molecular basis of this decrease remains unclear. To determine the mechanisms involved, changes in both pectic polysaccharides and cell wall enzymes were monitored during soaking. Two cultivars and one breeding line were studied. RESULTS: Soaking increased the activity of the cell wall enzymes rhamnogalacturonase, galactanase and polygalacturonase. Their activity in the cell wall was detected as changes in chemical composition of pectic polysaccharides. Rhamnose content decreased but galactose and uronic acid contents increased in the polysaccharides of soaked beans. A decrease in the average molecular weight of the pectin fraction was induced during soaking. The decrease in rhamnose and the polygalacturonase activity were associated (r = 0.933, P = 0.01, and r = 0.725, P = 0.01, respectively) with shorter cooking time after soaking. CONCLUSION: Pectic cell wall enzymes are responsible for the changes in rhamnogalacturonan I and polygalacturonan induced during soaking and constitute the biochemical factors that give bean cell walls new polysaccharide arrangements. Rhamnogalacturonan I is dispersed throughout the entire cell wall and interacts with cellulose and hemicellulose fibres, resulting in a higher rate of pectic polysaccharide thermosolubility and, therefore, a shorter cooking time. Copyright © 2011 Society of Chemical Industry