EFFECT OF COOKING ON THE PROFILE OF PHENOLICS, TANNINS, PHYTATE, AMINO ACID, FATTY ACID AND MINERAL NUTRIENTS OF WHOLE-GRAIN AND DECORTICATED VEGETABLE COWPEA (VIGNA UNGUICULATA L. WALP)

ABSTRACT

An experiment was conducted to determine the profile of phenolics, tannins, phytate, amino acid, fatty acid and mineral nutrients in whole‐grain and decorticated vegetable cowpea before and after cooking. Two cowpea varieties: C‐152‐White, having big grain and S‐1552‐White, having small grain with black eye were used for the study. Decortication of cowpea grain resulted in significant reduction (P ≤ 0.05) of total phenolics, total tannins and phytate contents of the two cowpea varieties. Comparison showed that cooking resulted in 19, 28, 28 and 37% losses in phenolics in whole‐grain C‐152, decorticated C‐152, whole‐grain S‐1552 and decorticated S‐1552, respectively. After cooking, whole‐grain and decorticated C‐152 retained 52.1 and 57.7% tannins while S‐1552 retained 59.4 and 49.5%, respectively. In the whole grain, C‐152 lost 72.2% phytate after cooking while S‐1552 lost 70.3%. For the decorticated samples, C‐152 lost 72.4% phytate after cooking while S‐1552 lost 71.2%. For the two cowpea varieties, decortication resulted in significant (P ≤ 0.05) losses of Ca, Fe, Mn, Mg, Zn, K and Cu while there was no significant effect on protein and amino acid profile. Cooking did not cause any significant change in the mineral nutrient composition of either the whole‐grain or decorticated cowpea. For the two cowpea varieties, bulk of the fat consisted of palmitic acid (23.2–27.3%) and stearic acid (53.5–59.8%) in the ratio of 1:2, approximately. Upon cooking, losses of crude protein were recorded in the whole‐grain and decorticated samples of the two cowpea varieties.

PRACTICAL APPLICATIONS

Cowpea is an important cheap source of protein particularly for the low‐income countries, especially in Africa and Asia. However, there is the need for some pretreatments before its cooking because of the presence of some undesirable antinutrients which often cause flatulence after consumption or they can render some minerals unavailable for body assimilation. This study investigated the role that African traditional method of decortication and cooking could play in reducing the concentration of antinutritional factors. We also showed how the traditional treatments could affect the other nutritionally important component of cowpea.

     

SELECTED CHEMICAL and PHYSICAL CHARACTERISTICS of CHICKEN BROTH FROM BROILER DEBONING BY-PRODUCTS

The characteristics of chicken broths from broiler breast frames (BF), mechanically-deboned bone residue (BR) and whole carcasses (WC) were investigated. Cooking times were for 1, 2, and 3 h. Increasing cooking times increased nitrogenous constituents, specific gravity, total soluble solids, turbidity and viscosity regardless of the type of raw material used. Broth pH was not affected by the length of cooking time. Broth viscosity was inversely related to broth temperature (25-65C). Chicken broths from BF and BR had equivalent or higher nitrogenous constituents when compared to those from WC. the main amino acids of chicken broths from BF and BR were similar to chicken flesh. Results of this study indicated that BF and BR are potential raw material alternatives in the processing of chicken broth.     

Free Amino Acids of Raw and Cooked Ground Beef and Pork

Ground beef and ground pork were cooked for 15 min on an electric griddle heated to a surface temperature of 121°C. Cooking reduced the total free amino acid (FAA) content from 25.23 to 17.60 mg/25g fresh weight in pork and from 32.77 to 30.09 mg/25g fresh weight in beef. Sixteen FAA were detected in both beef and pork; most individual FAA decreased during heating. Residues remaining after extraction of FAA from raw pork, when rehydrated (70% moisture) and heated (121°C, 15 min), contained only trace amounts of FAA. Free amino acids apparently were not produced under the cooking conditions employed in this study.     

Effect of Heat Treatments on In Vitro Digestibility of Delactosed Whey Protein as Determined by the Digestion Cell Technique

Diafiltered whey protein concentrates (WPC) were heated, in liquid form, under various conditions of time and temperature. Protein and amino acid digestibilities were determined by in vitro pepsin and pan-creatin digestion with continuous dialysis. Whey nitrogen digestibility decreased (P < 0.05) after heating at 121°C for 5000 sec. Heating WPC for 5000 set at temperatures below 121°C increased the digestibility of all amino acids except alanine and lysine at 75°C, and methionine and lysine at 100°C. In general, the longer was the heating period at 100°C or 121°C the lower was the amino acid digestibility. These results emphasized the importance of structural modifications brought about by heat treatments on protein digestibility.     

Physicochemical,milling and cooking quality of rice as affected by sowing and transplanting dates

The physicochemical, milling and cooking characteristics of three commercial varieties of paddy viz. Jaya, PR 106 and Pb. Basmati no. 1 as affected by different dates of sowing nursery and transplanting, were investigated. Grain yield was adversely affected with late sowing and transplanting dates. Significant differences were recorded on the yield of head rice and brokens in the three varieties grown under different sowing and transplanting dates. The effect of normal and late dates of sowing on 1000-kernel weight and grain dimensions was significant for both paddy and milled rice. Protein content of rice was not affected by sowing dates but late transplantings resulted in higher values. Free fatty acids in rice and bran were significantly increased with late sowing and transplanting dates, however, the amylose content decreased under these situations. Late transplanting dates decreased the minimum cooking time but increased the solid losses in gruel. The late transplantings deteriorated the organoleptic properties of cooked rice and had higher values for clearing and spreading.     

Technological properties of microwave parboiled rice

Two rice varieties, a short grain (Giza 175) and a long grain (Giza 181), were parboiled by soaking in water at 80–85 °C for 1.5 h and then dried in the microwave oven for 3, 5, 6 and 8 min. The effect of such parboiling treatment on milling output and technological properties (cooking and eating quality) of milled rice were studied. There was a negative significant correlation between head rice and the drying time and a positive correlation between the drying time and the broken grains. The effect of such treatment on the chemical composition of milled parboiled rice, i.e. amylose, protein, fat and ash contents, showed that the amylose content of Giza 175 variety significantly decreased while not affect in Giza 181 variety. No significant differences were obtained in protein, fat and ash contents by increasing drying time. Microwave drying was more pronounced on Giza 175 variety rather than Giza 181 one. However, the optimum cooking time of the parboiled samples of the two varieties was not affected as a result of increasing the microwave drying time.     

Effects of boiling and microwaving treatments on nutritional characteristics and antioxidant activities of Agaricus blazei Murril

The effects of boiling and microwaving on nutritional compositions, antioxidant components and antioxidant activities of fresh and frozen A. blazei Murril (AbM) were evaluated and compared. The results showed that the contents of crude protein, ash, total soluble protein, total soluble sugar, vitamin C, and total phenolics decreased by both cooking treatments, but no significant changes were observed in lipids. Amino acid composition analysis showed that the ratio of total essential amino acids to total amino acids increased, and the ratio of total non‐essential amino acids to total amino acids thus decreased by both cooking treatments. Boiling and microwaving significantly decreased the contents of glucose, galactose and mannose, and the effect of boiling was higher than that of microwaving. Furthermore, boiling and microwaving significantly decreased the DPPH‐scavenging activity and reducing power of AbM. Analysis of the relations between the antioxidant activities and total phenolic concentrations testified that the cooking treatments not only decreased the total phenolic contents, but also changed the types and relative amounts of phenolic compounds of AbM.     

Effect of tumbling time and cooking temperature on quality attributes of cooked ham

This study evaluates effect of tumbling time and cooking temperature on cooking rate, cooking loss (CL), colour, water activity and water‐holding capacity of cooked restructured ham rolls. In experiment were investigated three tumbling times (2, 4 and 6 h) at constant temperature (+4 °C) and three cooking temperatures (76, 86 and 96 °C). It was observed that CL decreased (P < 0.01) from 5.41% to 3.22% with tumbling time (2 h vs. 6 h) but increased (P < 0.01) from 2.35% to 7.25% along with cooking temperature (76 °C vs. 96 °C). In contrast, pH value increased (P < 0.01) from 6.18 to 6.24 with tumbling time (2 h vs. 6 h) but decreased (P < 0.01) from 6.22 to 6.17 along with cooking temperature (76 °C vs. 96 °C). In addition, high temperature had higher efficiency for thermal lethality than low temperature (F₀ values were 19 and 92 min at 96 and 76 °C, respectively). Intermediate tumbling (4 h) and cooking (86 °C) could be preferential.     

Extent of damage to amino acid availability of whey protein heated with sugar.

The effect of heat treatments, at various water activities (aW), on digestibility and on the availabilities of amino acids of whey protein samples in the presence of lactose was estimated by an in vitro digestion method with continuous dialysis. Four aW (0.3, 0.5, 0.7 and 0.97), three temperatures (75, 100 and 121 degrees C) and three heating periods (50, 500 and 5000 s) were selected. The initial lysine:lactose molar ratio was 1:1. Amino acid profiles showed that excessive heating of whey (121 degrees C, 5000 s) destroyed a significant proportion of cystine at all aW, lysine at aW 0.3, 0.5 and 0.7, and arginine at aW 0.5 and 0.7. At aW 0.3, 0.5 and 0.7, protein digestibility decreased (P less than 0.05) as the temperature increased from 75 to 121 degrees C for a heating period of 5000 s, and as the heating time was prolonged, from 500 to 5000 s at 121 degrees C. Excessive heating also decreased (P less than 0.05) the availabilities of all amino acids at aW 0.3, 0.5 and 0.7. The availabilities of lysine, proline, aspartic acid, glutamic acid, threonine, alanine, glycine and serine were particularly affected. Severe heating at aW 0.97 did not seem to favour the Maillard reaction, but the availabilities of cystine, tyrosine and arginine were decreased, probably as a result of structural modifications of the protein upon heating. Heating whey protein concentrates in the presence of lactose not only affected lysine, but also impaired enzymic liberation of other amino acids, according to the severity of heat treatments and aW.     

Content of amino acids in fresh and preserved physiologically immature grass pea (<Emphasis Type="Italic">Lathyrus sativus</Emphasis> L.) seeds

The aim of the work was to determine the level of amino acids in fresh and preserved physiologically immature grass pea seeds. Seeds of the grass pea cv. Krab at five stages of maturity, corresponding to dry matter content from 26 to 50%, were evaluated. The estimation was conducted at the stages of the raw material, the frozen product after 6 months storage cooked to consumption consistency, and the canned product within 6 months of production. In the later stages of seed maturity the content of total amino acids and of total non-essential, essential, and sulphuric amino acids computed per 100 g fresh matter increased. The computation per 16 g N showed increasing amounts of sulphuric amino acids and variation depending on the degree of maturity in the content of the remaining amino acids. Cystine with methionine were amino acids limiting the biological value of the first order, irrespective of the degree of maturity, leucine playing the same role with regard to the second order. For these amino acids the index of the limiting amino acid was 64–82 and 83–95 for the raw material, 72–77 and 91–99 for frozen seeds after cooking, and 70–75 and 86–99 for canned seeds. The integrated index of essential amino acids, depending on the degree of maturity, for the raw material was 120–126, for frozen seeds cooked 123–126, and for canned seeds 120–123.     

Radiation processing of minimally processed sprouts (dew gram and chick pea): effect on sensory,nutritional and microbiological quality

Sprouts have become an important part of the diet because of their nutritive value and low‐calorie content. The effect of radiation processing (1 and 2 kGy dose) on minimally processed dew gram and chick pea sprouts with respect to different quality parameters was studied over a storage period of 16 days at 8 °C. Radiation treatment and storage period did not have any significant effect on the sensory as well as nutritional qualities of irradiated dew gram and chick pea sprout. No significant change (P > 0.05) was observed in the colour and firmness of irradiated sprouts as compared to control samples. However, radiation processing resulted in significant reduction in aerobic plate counts (APC), coliform counts (CC), yeast and mould count (YMC) and staphylococci counts (SC). Radiation processing of dew gram and chick pea sprouts at 1 and 2 kGy extends the shelf life without affecting sensory and nutritional qualities.     

Nutritional quality of legume seeds as affected by some physical treatments, Part 1: Protein quality evaluation

The effect of water soaking, boiling, roasting, microwave cooking, autoclaving, fermentation and micronization on the nutritional quality of cowpea, pea and kidney bean was investigated. Pea seeds showed the highest crude fat, crude fiber and the lowest moisture contents while kidney bean had the lowest crude fat and the highest crude protein and ash contents. Glu and Asp were the main amino acids in all legumes while Cys and Met contents were the lowest. The protein efficiency ratio (PER), protein chemical score (CS) and the essential amino acid index (EAAI) of raw seeds ranged from 2.15 to 2.95, 39.07 to 68.30, and 55.49 to 62.84, respectively. Soaking, boiling, microwave cooking and autoclaving increased the total essential amino acids in all samples. Furthermore, raw and treated samples showed higher Lys content than the reference protein. Autoclaving was the most effective in improving protein quality followed by micronization, microwave cooking and fermentation. In addition, in vitro protein digestibility was improved after soaking, boiling, microwave cooking, autoclaving and fermentation but was reduced after roasting and micronization.     

Effect of Different Cooking Conditions on the Pasting Properties of Flours of Glutinous Rice Varieties from Lao People’s Democratic Republic

The effect of different rehydration temperatures (30, 40, and 50°C) and cooking times (2.7, 4.7, 6.7, 8.7, and 10.7 min) at 95°C on the pasting properties of three glutinous varieties (Thadokkham-11, Thadokkham-8, and Hom Mali Niaw) from Lao People’s Democratic Republic was investigated using rapid visco analyzer. Non-glutinous varieties (IR64 and Doongara) were also analyzed to compare glutinous (amylose <4.5%) and non-glutinous (amylose >15%) varieties. All rice flours took up water at significantly (p < 0.05) higher rates in the case of increased temperature and soaking time, resulting in a decrease in the onset temperature for pasting. Among the glutinous rices, Thadokkham-8 showed a significant (p < 0.05) decrease in peak viscosity in response to increased rehydration time and temperature. For this variety maximum viscosity (2403.3 mPas) was observed at 1 min of rehydration at 30°C and minimum viscosity (1852.0 mPas) at 15 min of rehydration at 50°C. The viscosity values of Thadokkham-11 and Hom Mali Niaw varieties increased to their highest values (1608.7 and 1477.7 mPa.s, respectively) with an increase in temperature to 40°C for 1 min. In general, the glutinous rices produced weaker gel than non-glutinous rices. Extended holding at cooking temperature (95°C) had a more significant (p < 0.05) effect on the glutinous varieties Thadokkham-8 and Thadokkham-11 than on the non-glutinous varieties (IR64 and Doongara) used in this study.     

大鲵汤加工过程中营养品质变化规律

分析大鲵汤加工过程中营养品质的变化规律。测定5个不同熬煮时间(30、60、90、120、150 min)条件下大鲵汤的一系列营养指标,包括可溶性蛋白质含量、粗脂肪含量、可溶性固形物含量、肌苷酸含量、定性定量脂肪酸组成和游离氨基酸组成。结果表明:大鲵汤中可溶性固形物与可溶性蛋白质含量在30~60 min间显著增加,在60~120 min间趋于平衡,在120 min后显著增加;肌苷酸含量随熬煮时间延长而增加;测得以棕榈酸、十六烯酸、油酸、亚油酸、花生四烯酸和二十四碳烯酸为主的16种脂肪酸,且饱和脂肪酸和多不饱和脂肪酸比值(saturated fatty acids/polyunsaturated fatty acids,SFA/PUFA)呈现出先减小后增大的趋势,在60 min时粗脂肪含量和脂肪酸含量适宜,且SFA/PUFA值最佳为1.37;大鲵汤中总氨基酸含量、必需氨基酸含量、鲜味氨基酸含量、必需氨基酸与非必需氨基酸比值(essential amino acid/non-essential amino acid,EAA/NEAA),随熬煮时间的延长先上升后下降,在60 min时达到峰值,总氨基酸含量为239.529 mg/100 g,EAA/NEAA值为0.858。在传统的常压熬煮条件下,熬煮时间为60 min时大鲵汤营养品质好,此时汤中脂肪含量适宜且SFA/PUFA值最佳,氨基酸含量最高。     

Thermal heat processing effects on antinutrients,protein and starch digestibility of food legumes

Thermal heat processing effects were investigated on antinutrients, protein and, starch digestibility of black grams, chick peas, lentils, red and white kidney beans. The tannin and phytic acid contents in these five food legumes ranged from 770–1100 mg/100 g to 970–1440 mg/100 g, respectively, whereas protein and starch digestibilities of the raw food legumes were 33.0–37.6% and 36.8–42.0%, respectively. Reduction in the levels of antinutrients, along with an improvement in protein and starch digestibility, was observed after cooking these food legumes. Antinutrient, including tannin (33.1–45.7%) and phytic acid (28.0–51.6%) contents, were reduced by different thermal heat treatments (121AC10, 121AC20, 121AC40, 121AC60, 121AC90, 128AC20). Maximum improvement in protein (95.7–105%) and starch (117–138%) digestibilities was observed on cooking these food legumes at 121 °C for 10 min (121AC10). However, ordinary cooking resulted in improvement of protein and starch digestibilities of the food legumes by 86.0–93.3% and 84.0–90.4%, respectively.     

不同处理方法对草菇呈味物质释放的影响

以草菇子实体为研究对象,以可溶性糖及糖醇、有机酸、5’-核苷酸、游离氨基酸组成和含量、分子质量分布为指标,研究常压蒸煮、高压蒸煮和酶解3?种处理方法对草菇呈味物质释放的影响,结果表明：常压蒸煮制备液可溶性糖及糖醇的总量显著降低,高压蒸煮制备液可溶性糖及糖醇的总量和原液基本相同,而酶解作用显著地提高了样品中可溶性糖的含量;和原液相比,常压蒸煮和高压蒸煮提取后有机酸总量显著增加,而复合酶解制备液有机酸总量显著降低;3?种处理方法作用后的游离氨基酸总量都有所增加,以高压蒸煮增加最显著,同时高压蒸煮制备液的鲜味氨基酸、甜味氨基酸以及苦味氨基酸的含量均显著增加;常压蒸煮和高压蒸煮制备后,大于3?000?Da组分的含量有所减少,高压蒸煮制备液中小于3?000?Da的组分含量最多,是制备呈味肽的重要来源。因此,不同处理方法对草菇呈味物质的释放有着明显差异,可以根据所需要的呈味物质采用不同的处理方法。     

Composition and in vitro digestibility of raw versus cooked white- and colour-flowered peas

Ten pea cultivars (four white-flowered, Pisum sativum ssp. hortense, and six colour-flowered, Pisum sativum ssp. arvense) grown in Latvia were analyzed and tested in in vitro experiments, as raw and cooked seeds. The colour-flowered (CF) had a greater proportion of hulls and a higher acid detergent fibre (ADF) content than white-flowered (WF) pea seeds (10.7 vs. 8.2% and 92.2 vs. 84.5 g/kg dry matter (DM), respectively). Three out of six CF varieties had a significantly greater amount of protein bound to neutral detergent fibre (NDF) than WF peas. The tannin content was higher in CF than in WF peas (8.46 vs. 0.37 g/kg DM). In vitro protein and amino acid digestibility was about 8% higher in WF than in CF varieties. Cooking decreased the tannin content in CF peas (8.46 vs. 5.51 g/kg DM) but had no effect on in vitro protein digestibility. Heat treatment reduced significantly trypsin inhibitor activity and amount of protein bound to NDF in CF and WF varieties (from 6.50 to 0.52 and from 6.54 to 0.46 trypsin inhibitor units (TIU)/mg DM; from 1.250 to 0.831 and 0.761 to 0.209 g N/100 g NDF, respectively). However, the protein bound to NDF content in pea DM increased in CF and decreased in WF varieties (from 1.525 to 2.145 and from 0.913 to 0.502 g N/kg DM, respectively). Cooking resulted in an increased NDF content over two times in both CF and WF pea seeds (from 122 to 259 and from 120 to 262 g/kg DM, respectively). The results suggest that colour-flowered pea may be considered as an interesting dietary alternative to white-flowered pea since cooking removes trypsin inhibitor activity (TIA), decreases tannins, and increases dietary fibre contents.     

基于GC-MS和氨基酸分析的羊肚菌汤适宜煮制时间研究

为确定羊肚菌汤适宜的煮制时间,本文对煮制20、40、60和120 min的羊肚菌汤的感官指标、挥发性风味物质及氨基酸进行量化分析。结果表明:羊肚菌汤在煮制40 min时色泽、气味和滋味最好,评分显著高于其他煮制时间（P<0.05）;煮制过程中共检测出49种挥发性风味物质,在煮制20、40、60和120 min的羊肚菌汤分别鉴定出22种、35种、31种、27种,醛类、酸类、酯类和烃类物质的总量在煮制40 min时显著高于其他煮制时间（P<0.05）,分别达到171.93、163.5、245.89和34.35 mg/g;鲜味氨基酸总含量在煮制40 min时显著高于其他煮制时间（P<0.05）,为21.54 mg/g,总氨基酸含量在煮制40 min时最高,为70.20 mg/g,表明煮制40 min是氨基酸溶出的高峰时期。羊肚菌汤的感官指标评分、挥发性风味物质种类及总量和氨基酸均含量及溶出在煮制0~40 min上升时期,在煮制40~60 min时开始逐渐下降,煮制60 min之后急剧下降。煮制时间过短或过长均不利于挥发性风味物质和各种氨基酸的呈现。本实验条件下,羊肚菌汤的煮制时间以40 min为宜,建议不要超过60 min。本文为羊肚菌汤的煮制时间提供了理论依据。     

和田红葡萄汁熬煮过程中游离氨基酸检测与分析

目的研究和田红葡萄汁在熬煮过程中,游离氨基酸含量随糖度升高的变化趋势。方法利用AccQ-Tag-高效液相色谱法对和田红葡萄熬煮汁中游离氨基酸进行定量检测。结果脯氨酸和精氨酸在慕萨莱思中含量最多,其次是赖氨酸、丝氨酸、谷氨酸、丙氨酸、苯丙氨酸,甲硫氨酸含量最少,半胱氨酸未检出。熬煮过程中多数氨基酸含量平稳上升,天冬氨酸和甘氨酸含量略有下降;当糖度达到26°Brix之后,丝氨酸、谷氨酸和甲硫氨酸含量有所下降。结论氨基酸的变化明显受到美拉德反应的影响,总氨基酸的浓缩为慕萨莱思自然发酵及其香味积累提供了前提条件。     

茶鲜叶萎凋时期乙烯利溶液对游离氨基酸组分的影响

探究萎凋过程中乙烯利溶液对离体茶鲜叶游离氨基酸含量的影响。以贵州省自主培育品种“黔茶1号”为试材,设置对照组、喷施乙烯利组及喷施乙烯抑制剂组。采用邻苯二甲醛（o-phthalaldehyde,OPA）法、9-芴甲基氯甲酸酯（9-fluorenylmethyl chloroformate,FMOC）法进行高效液相色谱在线衍生检测游离氨基酸。结果表明,鲜爽味氨基酸含量随萎凋时间延长而减少,甜味、苦味氨基酸含量随时间推移呈上升趋势。3类呈味氨基酸含量在萎凋期间对喷施乙烯处理响应不同。萎凋期间,鲜味氨基酸含量受乙烯诱导上调,差异显著发生在4、8 h;甜味氨基酸含量在各处理间总体差异不显著;各处理组苦味氨基酸含量在4、8 h无显著变化,12、20、24 h含量有所下降,差异不显著。鲜味氨基酸以茶氨酸为主,除谷氨酸含量在4 h时各处理间无显著差异外,茶氨酸、天冬氨酸及谷氨酸含量受乙烯诱导上调。甜味氨基酸中丝氨酸、脯氨酸含量不受乙烯调控,甘氨酸含量受乙烯诱导上调,丙氨酸含量不完全受乙烯调控。苦味氨基酸中组氨酸、酪氨酸、缬氨酸、异亮氨酸及亮氨酸含量受乙烯诱导上调。因此,萎凋期间喷施乙烯利溶液可以显著提高部分游离氨基酸含量。