Effect of Chitin as Coagulating Aid on Protein Yield, Composition and Functionality of Tomato Seed Protein Concentrates

The effectiveness of chitin as coagulating aid, protein coagulants and coagulation temperatures in recovering tomato seed proteins, and their effect on composition and emulsion properties of tomato seed protein concentrates (TSPC) were investigated. Citric acid, hydrochloric acid, or a mixture of citric acid and hydrochloric acid were used and chitin addition ranged from 0 to 1.0% (protein basis). Coagulation temperatures employed were 25°C, 60°C or 95°C. Samples with no chitin added resulted in significantly (P < 0.05) lower protein yields than samples with chitin addition. Ash content of the TSPC was significantly (P < 0.05) affected by chitin addition and coagulation temperature. Lowest crude fat content was obtained with citric acid at 25°C. Lowry protein and total nitrogen was highest without chitin addition. Samples coagulated at 25°C showed highest emulsion ability and emulsion stability. The least stable emulsions were produced with hydrochloric acid. Chitin addition did not affect emulsion properties.     

Compositional Factors That Affect the Emulsifying and Foaming Properties of Whey Protein Concentrates

An emulsion containing 30% fat was used to study emulsifying and foaming properties of commercial whey protein concentrates. Residual lipids, both total and phospholipids, inhibited foaming of dilute aqueous solutions of whey protein concentrates, whereas in aerated emulsions residual lipids were positively correlated with foaming. Under both test conditions the ash content was positively correlated with good and moderate foaming properties. Among the compositional factors which best predicted foaming of emulsions were sulfhydryls. Emulsions which contained insoluble whey proteins were highly stable but air incorporation was poor. When soluble whey proteins were utilized to stabilize emulsions, serum separation occurred more readily but did not correlate with good foaming properties.     

番茄籽蛋白的功能和结构

蛋白经加水溶解（5％W／V）和加热至50℃，氮溶指数NSI最高为30．02％。对可溶性番茄籽蛋白功能性质的测定表明，当乳化温度由30℃上升至50℃时，其乳化能力和乳化稳定性均随之上升，而当乳化温度上升至60℃时，乳化能力和乳化稳定性均显著下降；其起泡性略优于大豆分离蛋白，而泡沫稳定性不如大豆分离蛋白。对番茄籽蛋白的氨基酸组成分析表明，番茄籽蛋白氨基酸种类齐全，可以作为强化赖氨酸的蛋白源。SDS—PAGE电泳图显示，可溶性番茄籽蛋白中70％为盐溶性蛋白，水溶性蛋白相对分了质量分别为39．2、30．1和15．8kDa：盐溶性蛋白相对分子质量分别为66．1、28．1和16．8kDa；醇溶性蛋白相对分子质量分别为30．3和17．8kDa。     

Functional Properties of Seed Meals and Protein Concentrates From Tomato-processing Waste

ABSTRACT: Functional properties of tomato seed meals (whole and de-oiled) and protein concentrates (water, alkali, salt) were evaluated. Water and fat absorption of the meals were higher than the protein concentrates. The bulk density of the salt-extracted protein concentrate was the highest. The pH values of the meals were neutral, whereas those of protein concentrates were in the acidic pH range. The foaming capacity and stability of meals and concentrates were poor but improved slightly with the addition of salt and sugar. The emulsion capacity of meals and concentrates was good, while the emulsion stability was excellent except for alkali-extracted protein concentrate.     

Functional Characteristics of Milk Protein Concentrates and Their Modification

A major deterrent to the usage of milk protein concentrate (MPC), a high-protein milk product with increasing demand as a food and sports drink ingredient, has been its poor functional characteristics when compared with other milk protein products such as whey protein concentrate and sodium caseinates. This review discusses the recent research on functional properties of MPC, focusing on factors that may contribute to the poor functional characteristics before, during, and after production. Current research, methods employed, and new understanding on the causes of poor solubility of MPC at mild temperatures (about 20°C) has been presented, including loss of solubility during storage as these areas have received unprecedented attention over the past decade, and also affects other useful functional properties of MPC, such as emulsifying properties, gelation, and foaming. Processing methods, which include heat treatment, high-pressure application, microwave heating, ultrasound application, and enzyme and salts modification, have been used or have potential to modify or improve the functional properties of MPCs. Future research on the effects of these processing methods on the functional properties, including effects of enzyme hydrolysis on bitterness and bioactivity, has also been discussed.     

Yield Stress and Relative Viscosity of Tomato Concentrates: Effect of Total Solids and Finisher Screen Size

Yield stresses of tomato concentrates, prepared using two finisher screens (0.69 mm and 0.84 mm diam) were determined using the vane method, Casson model, and dynamic rheological data. Magnitudes of vane yield stress were higher than those using other methods. They increased with increase in total solids and were about the same in concentrates from both screen sizes. Magnitudes of Casson viscosities of concentrates and serum viscosities from 0.84 mm screen were slightly higher than those from 0.69 mm finisher screen.     

Intrinsic Viscosity of Tomato Serum as Affected by Methods of Determination and Methods of Processing Concentrates

Magnitudes of intrinsic viscosity of tomato serum determined from the slopes of three equations were not identical, but they showed common trends. Intrinsic viscosities of serums from concentrates obtained by evaporation of juice were lower than those obtained by evaporation of serum and reverse osmosis concentration of serum. Their magnitudes also were lower for serums from diluted and sheared concentrates.     

Functional Properties of Lupin Seed (Lupinus mutabilis) Proteins and Protein Concentrates

Functional and electrophoretic properties of the seed flour and a protein concentrate prepared by alkaline extraction from lupin seeds (Lupinus mutabilis, cultivar H-6) were investigated. SDS-PAGE indicated presence of 13 and 12 subunits in the seed flour proteins and the protein concentrate, respectively. Lupin protein concentrate had good water and oil absorption and gelation properties. Solubility of lupin proteins was minimum at a pH of 4.0 but increased rapidly beyond pH 5.0. Foaming capacity of the protein concentrate could be improved by increasing concentration as well as by adding NaCl and was influenced by pH and incorporation of certain carbohydrates. Emulsion properties of lupin proteins were concentration and pH dependent. Moist heat improved the in vitro digestibility of the seed proteins. The seed flour as well as the protein concentrate did not have detectable trypsin, chymotrypsin, and α-amylase inhibitory activities.     

Rheological Properties of Tomato Concentrates as Affected by Particle Size and Methods of Concentration

Shear rate-shear stress data were obtained on tomato concentrates made from juices that were produced using finisher screen openings (FSO): 0.020, 0.027, 0.033, and 0.045 in. In general, the apparent viscosity of the concentrates at a shear rate of 100 set^-1 increased with increase in FSO. However, concentrates made from juice using a 0.027 in FSO had the highest apparent viscosity. Magnitudes of yield stress of concentrates increased in direct proportion to FSO. Apparent viscosities of concentrates made by evaporating tomato juice were lower than those obtained either by evaporating the serum or by reverse osmosis concentration of the serum.     

The Production and Quality of Tomato Concentrates

The standards and specifications for the quality and composition of tomato concentrates are reviewed. The main quality parameters of tomato puree and paste are color, consistency and flavor. Overall, there is an absence of standardization of methods and instruments to define quality. While color can now be measured objectively, there are currently no standard color requirements for tomato concentrates. Rheological measurements on both tomato juice and concentrates are reviewed; the power law finds wide applicability, although other rheological characteristics, particularly time dependency, have received far less attention and there has been little effort to relate rheological understanding to the commonly used empirical tests such as consistency measurements. The volatiles responsible for flavor and odor have been identified to the point where the natural odor of tomato paste can be imitated. Attempts to develop objective methods as a substitute for sensory assessment are reviewed.     

Effect of Acylation Upon Extractability of Nitrogen, Phytic Acid and Minerals in Rapeseed Flour Protein Concentrates

Rapeseed flour (RF) and protein concentrates (RPC) were acylated with various levels of succinic or acetic anhydride. Compared with the unmodified control, 63% succinylation or 87% acetylation resulted in up to 45% increase in nitrogen and 95% decrease in phytic acid extractabilities in the first RF extract. At 21% succinylation or 55% acetylation, the extractability of phytic acid was more than double that of the unmodified control whereas the extractability of nitrogen was increased by 22%. A second extraction of the residual acylated RF with deionized water increased the extractability of phytic acid. For both first and second extracts, the extractability pattern of the major minerals followed that of phytic acid. Acylation of heat treated protein concentrate was not effective in increasing the nitrogen and decreasing the phytic acid extractabilities.     

Effect of Dehydration Methods on the Functionality of Plant Protein Concentrates

The significance of different dehydration methods for rice bran protein and soy protein coagulates on composition and functionality of the resulting protein concentrates was investigated. Minor compositional differences were found between the freeze-, spray- or drum-dried samples. Protein solubility data indicated limited effects of dehydration methods on heat coagulated samples but significant reduction of protein solubility by drum drying was found in the case of soy protein coagulated at room temperature. Water absorption capacity and emulsion properties were significant affected by dehydration methods but no consistent trends could be observed for fat absorption capacity. A significant increase of specific bread loaf volume, relaxation time of doughs and in some cases deformation of protein fortified samples was detected from freeze-dried to drum-dried samples. In general the effects of dehydration methods on protein functionality were more consistent for heat coagulated rice bran protein than for soy protein concentrates processed at ambient temperatures.     

不同萃取方法对番茄籽油理化性质与脂肪酸含量的影响

分别采用超临界ＣＯ２萃取技术和传统溶剂法从番茄籽中萃取脂肪油，经过甲酯化处理后，用气相色谱法分析出亚油酸等５种脂肪酸占总脂肪酸的９８．５％．同时对油的其它理化指标进行了测定。对测定结果进行了比较分析，说明超临界ＣＯ２萃取所得番茄籽油品质更好。并对番茄籽油的营养学机理作了讨论。     

Characteristics of Isolation and Functionality of Protein from Tomato Pomace Produced with Different Industrial Processing Methods

The seeds separated from tomato pomace may contain valuable protein with unique functional properties. The objectives of this research were to study the impact of industrial hot and cold break tomato processes on protein isolation from defatted tomato seed meal and determine the protein-related functional properties of defatted and non-defatted seed meals. The results showed that the high temperature of hot break process denatured the protein, resulting in the lower protein extraction yield from 9.07 % to 26.29 % for defatted hot break tomato seed (DHTS) compared to from 25.60 % to 32.56 % for defatted cold break tomato seed (DCTS) under various extraction conditions. Hot break process also significantly influenced protein-related functional properties of seed meals. Compared to DCTS, DHTS had higher water absorption capacity (WAC) and oil absorption capacity (OAC) based on the protein weight in the seed meal, but lower emulsifying ability (EA), emulsifying stability (ES), foaming capacity (FC), and foaming stability (FS) based on the whole seed sample weight. When compared to commercial soybean protein isolate (SP), the meals of hot break tomato seed (HTS), DHTS, and DCTS showed higher bulk density and WAC values. The FC and FS of tomato meals were inferior while the ES was superior to SP. High alkaline pH was beneficial to the protein extraction and achieved better EA, ES, FC and FS of all the samples. The results indicated that tomato seed meals have a great potential to be used as functional food ingredients.     

回收方法对鲢鱼肌浆蛋白和功能特性的影响

以鱼糜漂洗水为原料,研究35℃真空浓缩冷冻干燥(LT组)、35℃真空浓缩-调节pH值冷冻干燥(LT-pH组)、65℃真空浓缩冷冻干燥(HT组)、65℃真空浓缩-调节pH值冷冻干燥(HT-pH组)和调节pH值冷冻干燥(pH组)等不同回收方法得到的肌浆蛋白结构和功能特性。傅里叶红外光谱结果表明,5组回收方法得到的肌浆蛋白的α-螺旋和β-折叠相比回收前均有损失,且pH组回收得到的肌浆蛋白的结构和构象变化程度大于其他组;扫描电镜图表明5种回收方法均能使肌浆蛋白发生不同程度的破坏;功能特性表明,LT组肌浆蛋白的总巯基含量变化最大;pH组表面疏水性、乳化性和乳化稳定性变化最大;HT-pH组的热变性温度变化最大。说明肌浆蛋白的结构和功能特性随着回收方法的不同而不同。     

Effects of Heat Processing on the Functionality of Whey Protein Concentrates

The effects of heat processing on the composition and functionality of whey protein concentrations (WPC) were investigated. WPC was manufactured from milk, whey and retentate that had either been pasteurized at 72°C for 15 sec or had received no heat treatment. Eight combinations of heat treatment were utilized. Pasteurization of the milk had a positive effect on overrun and foam stability, but a negative effect on gel strength at pH 6.5, protein hydrophobicity, and neutral lipid content. Pasteurization of the whey resulted in decreased mineral content bud did not affect functionality. Pasteurization of the retentate caused a decrease in emulsion capacity, soluble β-lactoglobulin, solubility, whipped topping overrun and gel strength at pH 8.0.     

Changes in Microbiological and Lipid Characteristics of Cowpea Flours and Protein Concentrates During Storage

In dry- and wet-processed cowpea products, the yeast, mold and bacteria counts decreased during storage at 64% RH but, by the sixth month at 79% RH, microbial growth rendered the products unsuitable for food use. The high lipoxygenase activity in the dry-processed flours and protein concentrate were associated with the progressive loss of polyenoic fatty acids and increased free fatty acids, fat acidity and TBA values during storage. The wet-processed protein concentrate exhibited higher microbial counts than dry-processed cowpea products but showed improved storage stability due to the destruction of lipoxygenase by drum-drying.     

Effects of Chitosan on Yield and Compositional Data of Carrot and Apple Juice

Effects of chitosans on yield, titratable acidity, pH, soluble solids, and color of carrot and apple juice were evaluated. Carrots (Lange Rote Stumpfe) and apples (Golden Delicious) were treated with chitosan solutions (in 2% ascorbic acid) of two different concentrations and viscosities at 25°C between 0 and 120 min. The juices were obtained with a laboratory cage press following a standard program during 20 min. Treatments with chitosan produced no effect on juice yield but pH values and soluble solids were affected. Also chitosan treatment resulted in significant (P < 0.05) reduction of titratable acidity and color index. Reduction of β-carotene in carrot juice was also achieved and correlated with color index.