Tomato Seed Protein Concentrates: Effects of Methods of Recovery Upon Yield and Compositional Characteristics

Tomato seed protein concentrates (TSPC) were recovered from ground tomato seeds using alkaline extraction and three different protein coagulants (citric acid, citric acid/hydrochloric acid mixture or hydrochloric acid) at three coagulation temperatures (25°C 60°C or 95°C). The effect of this 3 × 3 protein recovery matrix on protein yield and composition of the freeze-dried TSPC was studied. No significant effect of protein coagulants on protein yield (TCA/heat coaguable protein) was found but it was significantly higher with samples coagulated at 25°C than when heat coagulation was applied. Coagulation procedures at room temperature resulted in lower moisture, crude fat and ash concentration than heat coagulated samples. Lowry protein content of TSPC was not significantly affected by recovery methods but crude protein content after coagulation with citric acid resulted in significantly higher values of the samples coagulated at 25°C than those at 95°C.     

Effects of pre-heating temperature and formulation on porosity,moisture content,and fat content of fried batters

The effect of pre-heating temperatures on moisture and fat contents, and porosity of fried batters was studied. Batter pre-heated at 60 °C showed higher moisture content, lower fat content and lower porosity than non-pre-heated batter and batters pre-heated at 70 and 80 °C. Moisture content, fat content, and porosity at 4 min frying for batters with different pre-heating treatments ranged from 35.08 to 39.37, 3.92 to 5.16, and 13.14 to 45.31 %, respectively. Because of significant reduction in fat content, 60 °C pre-heating temperature was chosen to study the effect of batter formulations on moisture and fat contents, and porosity. Different wheat to rice flour ratios were prepared, and then each batter was pre-heated at 60 °C. Batters with higher wheat flour content showed higher moisture content, and lower fat content and porosity than batters with higher rice flour.     

Isolation and Physico-chemical Properties of Enset Starch

Enset starch (Ensete ventricosum, Musaceae) has been examined for its chemical composition, amylose content and physico-chemical properties. The proximate composition of the starch on dry weight basis was found to be 0.16% ash, 0.25% fat, 0.35% protein, and 99.24% starch. The amylose content was 29%. Scanning electron microscopy (SEM) of enset starch granules showed characteristic morphology that was somewhat angular and elliptical. The starch has normal granule size distribution with a mean particle size of 46μm. It exhibits typical X-ray diffraction pattern of B-type with a distinctive maximum peak at around 17° 2θ Its moisture sorption pattern was similar to that of potato starch but much higher than maize starch. DSC parameters obtained from starch-water mixtures (1:2), namely, the enthalpy of gelatinization (ΔH: 21.6mJmg⁻¹), the onset temperature (T₀: 61.8°C), the peak temperature (T_p: 65.2°C) and the endset temperature (T_e: 71.7°C) were higher than those obtained for potato starch. Brabender viscosity curves of 6% starch paste showed lower peak viscosity (884 BU) than potato starch (1668 BU) but greater than maize starch (302 BU). The breakdown was also lower than potato starch but higher than maize starch. Retrogradation of enset starch was substantially greater than potato starch but less than maize starch.     

Isolation of Velvet Bean (Mucuna pruriens) Starch: Physicochemical and Functional Properties

The velvet bean (Mucuna pruriens) is an excellent potential starch source as it contains approximately 52 % of this carbohydrate. The physicochemical and functional properties of velvet bean starch were evaluated and compared to those of other starches. The chemical composition was: moisture 10.78 %; solid matter: protein 0.71 %; fiber 0.54 %; ash 0.28 %; fat 0.40 %; starch 98.1 %; and phosphorus 0.015 %. Amylose content was higher (39.21 %) than in tuber and cereal starches but similar to other legume starches. Average granule size was 23.6 μm, granules having an oval shape. Paste properties were: gelatinization temperature, 74.82 °C; gelatinization temperature range, 70—80 °C; and alkali number, 3.22. Gels produced with velvet bean starch were firmer than those produced with corn starch, and had a higher degree of retrogradation, even at high concentrations. At 90 °C, solubility was 16.2 % and swelling power was 16.17 g of water/g of starch. Given these properties, velvet bean starch has potential applications in food products requiring high temperature processing, such as jams, jellies and canned products.     

The effects of microfluidization on the physical,microbial, chemical,and coagulation properties of milk

This work examines the use of mild heat treatments in conjunction with 2-pass microfluidization to generate cheese milk for potential use in soft cheeses, such as Queso Fresco. Raw, thermized, and high temperature, short time pasteurized milk samples, standardized to the 3% (wt/wt) fat content used in cheesemaking, were processed at 4 inlet temperature and pressure conditions: 42°C/75 MPa, 42°C/125 MPa, 54°C/125 MPa, and 54°C/170 MPa. Processing-induced changes in the physical, chemical, and microbial properties resulting from the intense pressure, shear, and cavitation that milk experiences as it is microfluidized were compared with nonmicrofluidized controls. A pressure-dependent increase in exit temperature was observed for all microfluidized samples, with inactivation of alkaline phosphatase in raw and thermized samples at 125 and 170 MPa. Microfluidization of all samples under the 4 inlet temperature and processing pressure conditions resulted in a stable emulsion of fat droplets ranging from 0.390 to 0.501 μm, compared with 7.921 (control) and 4.127 (homogenized control) μm. Confocal imaging showed coalescence of scattered fat agglomerates 1 to 3 μm in size during the first 24 h. We found no changes in fat, lactose, ash content or pH, indicating the major components of milk remained unaffected by microfluidization. However, the apparent protein content was reduced from 3.1 to 2.2%, likely a result of near infrared spectroscopy improperly identifying the micellar fragments embedded into the fat droplets. Microbiology results indicated a decrease in mesophilic aerobic and psychrophilic milk microflora with increasing temperature and pressure, suggesting that microfluidization may eliminate bacteria. The viscosities of milk samples were similar but tended to be higher after treatment at 54°C and 125 or 170 MPa. These samples exhibited the longest coagulation times and the weakest gel firmness, indicating that formation of the casein matrix, a critical step in the production of cheese, was affected. Low temperature and pressure (42°C/75 MPa) exhibited similar coagulation properties to controls. The results suggest that microfluidization at lower pressures may be used to manufacture high-moisture cheese with altered texture whereas higher pressures may result in novel dairy ingredients.     

Characteristics of Milk,Cheddar-Like and White Cheese Obtained from Three Goat Phenotypes during Three Lactation Periods

Goat's milk from three phenotypes: Shami, Local, and Mixed was collected during three lactation periods in 2002. The milk was analyzed for moisture, protein, fat, ash, and lactose content. Also milk was examined for yeast, mold and bacterial content. Cheddar and white cheese were manufactured from goat's bulk milk and examined for chemical composition and evaluated for color, taste and flavor, appearance, and texture and aroma. Results showed that the chemical composition of goat's milk varied significantly during the whole year and also among the three goat phenotypes. Local goats produced milk at the first lactation period with highest (44.6%) fat content: the lowest fat content was 29.8% for the Mixed color phenotype at the end of the year. Protein showed the same trend. Shami goat produced milk lower in lactose and ash content than the mixed color breed, whereas the Local (black) produced milk having intermediate content of lactose and ash. Cheddar and white cheese were highly acceptable. Their composition varied—cheddar cheese was higher in protein and NSF but slightly lower in fat content. White cheese retained more lactose. Goat's milk of Shami, Local (black) and Mixed color phenotypes were found to be highly contaminated with bacteria and mold due to lack of hygiene. Milk contained low number of pathogenic bacteria. Using a pasteurization temperature at 73°C for 16 seconds was found to eliminate them.     

Grinding Time and Pressure Developed in Beef and Pork: Effects of Temperature and Fat

Pressure on the inside face of grinder plates was measured during meat grinder operation using four transducers mounted at various distances from the center to the periphery of the plate face. Pressure during grinding of 11.4 kg batches of beef or pork was increased significantly (P<0.05) with low temperature and high fat content. The pressure increase was about 25% (409.5 kPa to 512.3 kPa) when temperature was decreased from 4°C to - 2°C and about 500% (from 177.2 kPa to 875.6 kPa) when fat content was increased from 10.1% to 44.6%. Pressure also increased (P<0.05) by about 30% from the center (344.7 kPa) to the periphery (448.5 kPa) of the plate. Overall, beef resulted in 61% greater pressure than pork.     

Canavalia ensiformis Tailing Starch: A Functional Source of Dietary Fiber

Physicochemical and functional characteristics of the tailing starch isolated from the legume Canavalia ensiformis were determined. Proximal composition was 2.86% protein, 4.05% fiber, 0.37% fat, 1.51% ash and 91.33% carbohydrates as nitrogen‐free extract. Total dietary fiber content was 21.3%, soluble fiber was 2.2%, and insoluble fiber was 19.1% as determined by the Prosky method. Amylose content as quantified by differential scanning calorimetry (DSC) was 39.35%. Gelatinization temperature range as determined by DSC was from 77.9 °C to 88.1 °C, with 81.6 °C being the peak temperature. Transition enthalpy was 10.1 J/g. Swelling power ranged from 4.36 g water/g starch at 60 °C to 11.87 g water/g starch at 90 °C. Water solubility, analyzed within the same temperature interval, ranged from 3.29% to 16.93%. Water absorption capacity was 4.22 g water/g starch at 60 °C and 10.33 g water/g starch at 90 °C. Syneresis in a 6% gel stored at 4 °C for 24 h was 25.66 mL water/50 mL gel. Clarity, expressed as transmittance, was 10.46%. Initial pasting temperature was 93 °C, breakdown was —22 Brabender Units (BU), consistency was ‐5 BU, and setback was 17 BU.     

Aqueous Extraction of Oil from Palm Kernel

Aqueous extraction of oil from palm kernel was investigated on a laboratory scale, varying several processing parameters, with main emphasis on their effects upon oil yield. Oil was obtained as a clear, yellowish, separate phase. Maximum oil yield was obtained at 20 min of grinding with a Waring Blendor, extraction temperature 45°C, grinding temperature 60°C, and pH 7.0. Increasing the grinding time and extraction temperature did not improve the oil yield. On either side of pH 7.0 not only was the oil yield decreased but an emulsion tended to form. The dilution ratio had no effect on the oil yield. Oil yield was increased further by re-extraction.     

Effect of storage conditions on nutritional quality and color characteristics of quinoa varieties

To maintain grain quality and prevent loss, effective storage systems are required. The aim of this study was to evaluate the effects of storage duration (0, 60, 120, 180, 240, 300, 360 days) and temperature (4, 10, and 25 °C) on proximate and nutritional components, and color properties of Mint Vanilla and Titicaca quinoa varieties. The results showed that the increase in storage duration and temperature leads to changes in the grain moisture, protein and ash contents, nutritional component and color properties. There was an increase in ash content at 25 °C, moisture content at 10 and 25 °C, and protein content at 4 °C in the stored grains compared with the grains on the initial of storage for Mint vailla variety. Whereas, there was an decrease in ash and protein content for all the temperature at the end of 360 days storage for Titicaca variety. Overall, there was a decrease (except Fe, Zn, Co, Ni, Cd and Pb) in the nutritional component of both quinoa varieties. L1, H° and WI values decreased, and a1, b1 and C1 values increased as a function of storage duration and temperature and showed some temperature-dependent degradation for both quinoa varieties.     

Nutritional quality of spray dried protein hydrolysate from Black Tilapia (Oreochromis mossambicus)

The nutritional quality of spray-dried protein hydrolysate from black tilapia, a fresh water fish, was evaluated. Hydrolysed protein from Oreochromis mossambicus was spray-dried at two different temperatures of 150 °C/76 °C (inlet/outlet temp) and 180 °C/90 °C. Proximate analyses revealed that the dried hydrolysates consisted of 37.7–49.6% protein, 2.6–2.8% fat, 1.6–4.0% moisture and 8.6–8.7% ash. The higher drying temperature used was found to significantly decrease the contents of all amino acids analysed. Nevertheless, the protein quality of both dried hydrolysates was found to be high, with in vitro digestibilities of 88.4 and 92% and protein digestibility corrected amino acid scores of 0.34 and 0.82, respectively. In addition, the predicted protein efficiency ratios of the dried hydrolysates were calculated to be 2.97 and 2.53.     

Roles of components of rice-based fat substitute in gelation

The roles of maltodextrin, protein and fat in the gelation of the rice-based fat substitute were investigated. Rheological properties and gel strength of samples were measured. Results showed that the rising rates of both G′ and G″ of rice starch-based fat substitute were higher than those of rice-based fat substitute when temperature was lower than 35 °C. G′ was equal to G″ at 60 °C for 25% rice-based fat substitute whilst it was at 35 °C for rice starch-based fat substitute. The presence of rice protein and fat increased G′ and G″. Gel strength of rice-based fat substitute was lower than that of starch-based fat substitute at 25% solid content. However, gel strength of a fat substitute increased in the presence of protein. SEM showed that protein particles aggregated to gel. Therefore, protein in rice-based fat substitute gelled firstly, followed by maltodextrin which formed the main matrix of the rice-based fat substitute gel. Fat benefited for gel formation.     

Wheat Hardness: Time Required to Grind Wheat with the Brabender Automatic. Micro Hardness Tester

The Brabender automatic micro hardness tester was used to measure the time required to grind 4g of wheat. Effects of temperature and moisture were determined. Increasing temperature from 15 to 40°C generally decreased grinding time, but differentiation among samples was better at 15°C than at higher temperatures. Increasing moisture content increased the grinding time of soft wheat much more than it increased the grinding time of hard wheat. The tester can detect differences related to milling properties of hard wheats, hardness among some wheat classes and among some varieties representing a single class of wheat. The instrument can also be used to evaluate hardness of plant-breeders' samples, so that selections with extreme hardness or softness can be discarded, and to distinguish between hard and soft wheats in marketing channels.     

Effect of processing and cooking on the content of minerals and protein in pasta containing buckwheat bran flour

Research was conducted to determine the effect of processing and cooking on the ash content and mineral composition and on protein content and amino acid composition of spaghetti that was fortified with 250 g kg^?1 buckwheat bran flour (BBF). Extrusion and drying temperature had little or no effect on ash and mineral content of spaghetti containing BBF. Drying temperature did not affect protein content; however, a 31% reduction in lysine content was observed in spaghetti containing BBF dried at 90 °C. Cooking spaghetti fortified with BBF reduced ash content by 28%. Reduction in ash content was reflected by an average decrease in potassium of 62%, in copper of 45%, and in zinc of 11%. Cooking had little or no effect on content of calcium, iron, magnesium, or manganese. As a result of material leaching from spaghetti during cooking, the protein content and content of each amino acid (db) were greater in cooked than uncooked spaghetti. Copyright © 2007 Society of Chemical Industry     

Electrophoretic characterization of protein interactions suggesting limited feasibility of accelerated shelf-life testing of ultra-high temperature milk

Accelerated shelf-life testing is applied to a variety of products to estimate keeping quality over a short period of time. The industry has not been successful in applying this approach to ultra-high temperature (UHT) milk because of chemical and physical changes in the milk proteins that take place during processing and storage. We investigated these protein changes, applying accelerated shelf-life principles to UHT milk samples with different fat levels and using native- and sodium dodecyl sulfate-PAGE. Samples of UHT skim and whole milk were stored at 20, 30, 40, and 50°C for 28 d. Irrespective of fat content, UHT treatment had a similar effect on the electrophoretic patterns of milk proteins. At the start of testing, proteins were bonded mainly through disulfide and noncovalent interactions. However, storage at and above 30°C enhanced protein aggregation via covalent interactions. The extent of aggregation appeared to be influenced by fat content; whole milk contained more fat than skim milk, implying aggregation via melted or oxidized fat, or both. Based on reduction in loss in absolute quantity of individual proteins, covalent crosslinking in whole milk was facilitated mainly by products of lipid oxidation and increased access to caseins for crosslinking reactions. Maillard and dehydroalanine products were the main contributors involved in protein changes in skim milk. Protein crosslinking appeared to follow a different pathway at higher temperatures (≥40°C) than at lower temperatures, making it very difficult to extrapolate these changes to protein interactions at lower temperatures.     

Some Physico-chemical Properties of Dioscorea Starch from Ethiopia

The chemical composition, amylose content and physio-chemical properties of dioscorea starch (Dioscorea abyssinica, Fam. Dioscoreaceae) from Ethiopia have been investigated. The proximate composition of the starch on dry weight basis was found to be 0.1% ash, 0.5% protein, 1.0% fat and 98.4% starch. The amylose content was 29.7%. Scanning electron microscopy (SEM) showed rounded granules. Particle size analysis revealed granule size distribution with a mean particle size of 29.2 μm. X-ray diffraction study showed a pattern that is typical of B-type with a distinctive maximum peak at around 17° 2 T. The moisture sorption pattern, the swelling power and the solubility values were determined and found to be lower than potato starch. Brabender viscosity curves of 6% starch paste showed a peak viscosity of 781 BU. The breakdown and retrogradation of dioscorea starch were 25 and 501 BU, respectively. DSC parameters of starch-water mixture (1:2) exhibited an onset temperature (T_o) of 64.2°C, a peak temperature (T_p) of 68.2°C and an endset temperature (T_e) of 74.8°C. The enthalpy of gelatinization (ΔH) was 19.2 mJmg⁻¹.     

TASTE PANEL TESTING OF UHT FLUID DAIRY PRODUCTS1

Fluid dairy products processed by ultra-high-temperature steam injection were evaluated by two independent panels to determine the effect of % fat and process and storage conditions of flavor. Fat content from 0.5 to 10.5%, process time from 3.4 to 20.3 s, process temperature from 138 to 149°C, storage time from zero to 48 weeks, and storage temperature from 4 to 40°C were studied. The two panels consisted of an untrained consumer panel and a trained panel of dairy judges. Scores from both panels correlated well. Scores on all samples stored at 4°C generally increased through time while those at 40°C had declining scores. Samples with 3.25% fat generally scored higher than those with 0.5 or 10.5% fat. An empirical relationship and nomograph were formulated between diary judge score, % fat, storage temperature and storage time. Milk produced and stored at or near room temperature may be predicted to receive moderate scores through one year.     

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.     

Effect of Cross-Section Differences and Drying Temperature on the Physicochemical, Functional and Antioxidant Properties of Giant Taro Flour

Giant swamp taro, Cyrtosperma merkusii, consumed and regarded as indigenous food in many regions of Cameroon, is a potential bio-source of antioxidants as well as flours for use in different food formulations but which has not been widely studied. The present study was carried out to determine the effect of drying conditions on the chemical composition as well as the physical and functional properties and antioxidant activity of flours of this tuber. Slices of the yellow and mixed sections of the tubers were processed into flours by sun-drying (temperature ≈35 °C) and hot air electric drying at varying temperatures (50 °C, 60 °C, and 70 °C) before milling. Drying temperature and technique showed marginal effect on the protein, fat, fiber, ash, and carbohydrate content of taro flours. Color attributes, physical and functional properties, 1,1-diphenyl-2-picryl-hydrazyl radical antioxidant activity, as well as reducing power of flours were found to vary significantly (P?<?0.05) due to either the drying temperature or method. Hot air electric drying at lower temperatures (<70 °C) produced flour with higher water absorption capacity (WAC), water solubility index (WSI), porosity, bulk density, and preserved antioxidant activity of flour, whereas sun-drying was associated with flours of higher WSI but lower WAC, and lower antioxidant capacity. It was noticed that carotenoids and ascorbic acid contributed to the antioxidant activity in taro flours, and taro flours made of different taro portions showed different antioxidant mechanisms. This study highlights the low temperature hot air-drying method as a very good lead for preparation of effective natural functional flours for culinary system.     

Extraction of Cholesterol and Other Lipids from Dried Egg Yolk Using Supercritical Carbon Dioxide

Supercritical carbon dioxide extraction was investigated for removal of cholesterol and lipid components from dried egg yolk. Four different combinations of pressure and temperature were used including 163 atm/40°C, 238 atm/45°C, 306 atm/45°C and 374 atm/55°C. As temperature and pressure were increased, more lipids and cholesterol were removed. Extraction at 306 atm/45°C or 374 atm/55°C removed approximately two-thirds of the cholesterol. Phospholipids and protein were concentrated under the supercritical extraction conditions used. Sponge cake volume was significantly (P < 0.05) improved at extraction conditions of 163 atm/40°C, 238 atm/45°C and 306 atm/45°C, which may have been due to higher phospholipid and protein concentrations. Only extraction at 374 atm/55°C significantly (P < 0.05) impaired emulsion stability of egg yolk.