Showing papers in "Journal of Food Science in 1976"
Journal Article•
TL;DR: In this paper, the functional properties of protein concentrates from alfalfa leaves (ALP) prepared by several methods were determined, including extraction of the lipids from ALP with acetone decreased solubility slightly, increased the bulk density, and reduced water and fat absorption capacities.
Abstract: Functional properties of protein concentrates from alfalfa leaves (ALP) prepared by several methods were determined. Minimum solubilities occurred around pH 3.5–4; sodium chloride 0.05–0.2M had little effect on minimum solubility. Extraction of the lipids from ALP with acetone decreased solubility slightly; increased the bulk density (2-3-fold); and reduced water and fat absorption capacities by 50% compared to the controls. Both emulsifying activities and emulsion stabilities of ALP samples were generally better than those of soy protein concentrate but poorer than those of soy sodium proteinate i.e., average of 57, 48 and 87 and 60, 50 and 90%, respectively. Emulsifying capacity of ALP samples were reduced following acetone extraction.
403 citations
TL;DR: Functional properties of protein concentrates from alfalfa leaves (ALP) prepared by several methods were determined and both emulsifying activities and emulsion stabilities of ALP samples were generally better than those of soy protein concentrate but poorer thanThose of soy sodium proteinate.
Abstract: Functional properties of protein concentrates from alfalfa leaves (ALP) prepared by several methods were determined. Minimum solubilities occurred around pH 3.5–4; sodium chloride 0.05–0.2M had little effect on minimum solubility. Extraction of the lipids from ALP with acetone decreased solubility slightly; increased the bulk density (2-3-fold); and reduced water and fat absorption capacities by 50% compared to the controls. Both emulsifying activities and emulsion stabilities of ALP samples were generally better than those of soy protein concentrate but poorer than those of soy sodium proteinate i.e., average of 57, 48 and 87 and 60, 50 and 90%, respectively. Emulsifying capacity of ALP samples were reduced following acetone extraction.
402 citations
TL;DR: In this article, myofibril fragmentation index (MFI) and Warner-Bratzler (W-B) values were determined quantitatively by measuring the absorbance of a myoftibril suspension, and it was observed that MFI increased during postmortem storage for L and ST, but increased only slightly for PM.
Abstract: Samples were removed from bovine longissimus (L), semitendinosus (ST) and psoas major (PM) muscles at 1, 2, 3, 6, 7, 10 or 13 days postmortem stored at 2°C or 25°C. Myofibril fragmentation index (MFI) and Warner-Bratzler (W-B) shear-force values were determined on steaks from each muscle. Myofibril fragmentation index (MFI) was determined quantitatively by measuring the absorbance of a myofibril suspension. It was observed that MFI increased during postmortem storage for L and ST, but increased only slightly for PM. These results paralleled those changes in myofibrils observed with phase and polarized light microscopy. Both MFI and W-B shear-force values changed greatly from 1 to 3 days postmortem with a lesser change occurring after 3 days in L and ST muscles. In PM muscle, however, only a slight change in MFI and W-B shear-force occurred during postmortem storage. Elevated storage temperature (25°C) caused an accelerated change in both MFI and W-B shear-force in L and ST muscles; however, storage temperature had little effect on PM muscle. L and ST muscles responded similarly to postmortem storage, but PM muscle was characteristically different from the L and ST muscles. These findings demonstrate the differences and similarities of muscles to postmortem storage and further elucidate the role of myofibrillar proteins in meat tenderness.
314 citations
TL;DR: The functional properties of rapeseed meal, flours, protein concentrates and isolate were evaluated in comparison with those of soybean as discussed by the authors, showing that rapeseed flours were comparable to soybean flour in water absorption but showed much higher nitrogen solubility, fat absorption, oil emulsification, whippability and foam stability.
Abstract: The functional properties of rapeseed meal, flours, protein concentrates and isolate were evaluated in comparison with those of soybean. Generally, rapeseed products were lower in protein but higher in crude fiber and ash contents than the corresponding soybean flour, concentrate or isolate, Rapeseed flours were comparable to soybean flour in water absorption but showed much higher nitrogen solubility, fat absorption, oil emulsification, whippability and foam stability. The viscoamylograph curves for rapeseed flours were characterized by intermediate peak and high cold viscosities, but their gelation properties were poor. Unfortunately, flour from the low glucosinolate cultivar, Tower, contained 1.2 mg/g of glucosinolates, primarily oxazolidinethione, and only the detoxified concentrates and isolate would be safe for human consumption. Rapeseed concentrates and isolate showed excellent water-and fat-holding capacity and the isolate was high in oil emulsification and whipping characteristics. While superior to soybean products in most functional tests, the utilization of rapeseed products may be limited by green or brown colors in the aqueous slurries.
216 citations
TL;DR: A beverage consisting of water, whole soybeans (including hulls), sugar and flavor has been developed in this article, which includes 0.5% sodium bicarbonate, grinding with water in a hammermih, heating the slurry to 200° F, homogenizing, neutralizing, dilution, addition of sugar and flavour, pasteurizing and rohomogenizing.
Abstract: A beverage consisting of water, whole soybeans (including hulls), sugar and flavor has been developed. Preparation includes soaking and then blanching the whole soybeans in 0.5% sodium bicarbonate, grinding with water in a hammermih, heating the slurry to 200° F, homogenizing, neutralizing, dilution, addition of sugar and flavor, pasteurizing and rohomogenizing. Enzyme inactivation by blanching prior to grinding of soaked beans was found to completely prevent formation of painty (oxidized) flavor and result in a bland flavored product. Trypsin inhibitors were also inactivated by blanching. A sufficient degree of tender-ization of soybean tissue during the soak and blanch treatments was necessary to obtain good mouth feel and colloidal stability. Homogenizing conditions such as temperature and pressure were also important; when the soybeans had been blanched to a LEE-Kramer Tenderometer reading of 300 lb or below and homogenization was done at 200°F and 3500 psi, the resulting beverage showed zero separation after 2 months refrigerated storage. Dilution to below 1% protein had no effect on colloidal stability. Coulter Counter measurements of the beverage indicated that 81% of the particles fell between 3.4-7.3 microns which is larger than the defined colloidal particle range. Recoveries of protein and total solids based on the raw soybean were 99% and 90%, respeo tively.
205 citations
TL;DR: In this paper, the frequency spectra and amplitude-time characteristics of sounds produced by biting crisp foods were studied. And a model system involving a generalized cellular structure was proposed to explain the generation of a crisp sound, which is the result of the rupture of a single cell or cell wall.
Abstract: The theory is proposed that crispness is primarily an acoustical sensation. The frequency spectra and the amplitude-time characteristics of sounds produced by biting crisp foods were studied. The frequencies present in crisp sounds cover a broad range. Amplitude-time plots show irregular variations in loudness with time. A model system involving a generalized cellular structure is proposed to explain the generation of a crisp sound. As a crisp cellular material is crushed, a series of sounds is produced. Each sound is the result of the rupture of a single cell or cell wall.
198 citations
TL;DR: In this article, a set of rigorous, broadly applicable equations for effective heat capacity during the freezing and thawing of foods and biological materials were derived based on a modified form of the freezing point depression equation.
Abstract: Based on a modified form of the freezing point depression equation we have derived a set of rigorous, broadly applicable equations for effective heat capacity during the freezing and thawing of foods and biological materials. The equations have been integrated with respect to temperature, thereby providing a set of useful equations for enthalpy during freezing and thawing. The validity and utility of the equations are demonstrated using data from the literature. Methods for adjusting the equations to account for changes in water content and fat content are presented. The enthalpy equations are useful for calculating heat-transfer loads during freezing and thawing, and the heat capacity equations can be advantageously used in differential equations for calculating freezing and thawing heat-transfer rates.
175 citations
TL;DR: The phytohemagglutinins also play an important role contributing to the poor nutritive value of some legumes, particularly those belonging to the genus Phaseolus, and are believed to exert a nonselective adverse effect on the absorption of nutrients from the intestinal tract rather than a direct effect onThe digestive process.
Abstract: Proteins capable of inhibiting the proteolytic activity of digestive enzymes are common constituents of legumes. These protease inhibitors are generally believed to be largely responsible for the poor digestibility of the protein of legumes which have been inadequately cooked. This reduction in digestibility is invariably accompanied by an enlargement of the pancreas. Recent studies in the author's laboratory, however, have revealed that only about 40% of the growth-depressing activity and a similar fraction of the pancreatic hypertrophic effect of unheated soybeans can be attributed to the action of the trypsin inhibors. The poor digestibility and pancreatic hypertrophy that cannot be accounted for by the trypsin inhibitors are most likely the consequence of the refractory nature of the undenatured protein to attack by trypsin. The phytohemagglutinins also play an important role contributing to the poor nutritive value of some legumes, particularly those belonging to the genus Phaseolus. In this case the phytohemagglutinins are believed to exert a nonselective adverse effect on the absorption of nutrients from the intestinal tract rather than a direct effect on the digestive process.
168 citations
TL;DR: In this article, the shrinkage in dehydration of root vegetables such as carrots, potatoes, sweet potatoes and radishes was investigated, and three drying models were postulated for the formulation of the relation between the changes of the surface area and the moisture contents.
Abstract: The shrinkage in dehydration of root vegetables such as carrots, potatoes, sweet potatoes and radishes was investigated. The samples were dried in flowing hot air. The surface areas were measured by photographing the samples. Three drying models were postulated for the formulation of the relation between the changes of the surface area and the moisture contents. The uniform drying model, which in the case of drying is that the shrinkage in volume equals the volume of water lost by the evaporation, agreed with the measured values during the early stages of the drying. The core drying model by assuming the formation of the dried layer at outer side of material was better in agreement with the experimental results. The semicore drying model, which is the intermediate model between the uniform and the core drying model, and the empirical equations of the shrinkage were also considered.
142 citations
TL;DR: In this paper, the necessary pasteurization temperature, F and z values for pectinesterase inactivation were developed for three varieties of orange juices and one grapefruit juice.
Abstract: The necessary pasteurization temperature, F and z values for pectinesterase inactivation were developed for three varieties of orange juices and one grapefruit juice. Since common commercial practice involves blending various orange varieties, the recommended conditions are those for the most heat resistant variety. For an FT=1.0 min, the recommended processes are T = 194°F with z = 12.2 for orange juice and T = 186°F with z = 9.3 for grapefruit juice.
131 citations
TL;DR: In this paper, the principles of the flavor profile method were used to establish the relationship between the flavor of potatoes and their total glycoalkaloid and total phenolic contents.
Abstract: The principles of the flavor profile method were used to establish the relationship between the flavor of potatoes and their total glycoalkaloid and total phenolic contents. Tuber tissues from the seven potato clones that had glycoalkaloid contents in excess of 14 mg/100g were rated as bitter by the taste panel. The correlation between glycoalkaloid contents and bitterness ratings for the 13 clones included in the study was highly significant (r = 0.93). Tissues that had glycoaikaloid contents in excess of 22 mg/100g also produced a mild to severe burning sensation in the mouth and throat. The intensity of the burning sensation was highly correlated (r = 0.97) with glycoalkaloid contents. The correlations between phenolic contents and either bitterness or burning ratings were not significant.
TL;DR: In this paper, the use of or-galactosidase from Mortierella vinacea to remove raffinose and stachyose in soybean milk was studied.
Abstract: The use of or-galactosidase from Mortierella vinacea to remove raffinose and stachyose in soybean milk was studied. Disrupted M. vinacea mycelium was further entrapped within 7.5% polyacrylamide gel and its general properties were determined. It was observed that there were only slight changes in optimal pH and temperature after the α-galactosidase was immobilized, while the recovery of α-galactosidase activity was approximately 65%. Three different forms (undisrupted, disrupted, and entrapped) of M, vinacea mycelium were used to hydrolyze the oligosaccharides in soybean milk Disrupted mycelium gave the highest hydrolysis ratio in these three different forms; however, it was found that after long-term usage at 50°C, the thermal stability of the disrupted mycelium was relatively poor. A fluidized reactor was chosen to be used in this study.
TL;DR: In this paper, the authors investigated the mechanism of cooking rice and concluded that the cooking process comprises two mechanisms; at temperatures below 110°C the cooking rate is limited by the reaction rate of rice components with water; and at temperatures above 120°C it is limited due to the rate of diffusion of water through the cooked layer toward the interface of uncooked core where the reaction occurs.
Abstract: The mechanism of cooking rice was investigated in this study. The rheological method using the parallel plate plastometer was adopted for measurement of the degree of cooking. The range of temperatures measured ran from 75–150°C. Experimental results showed that cooking rate followed the equation of a first order chemical reaction. We designated the proportional constant as the cooking rate constant, but the slope of Arrhenius plots of the cooking rate constants changed around 110°C. The activation energy of cooking at temperatures below 110°C and above 110°C was about 19,000 and 8,800 cal/mol respectively. The influences of water soaking time before cooking were also studied. We concluded that the cooking process comprises two mechanisms; at temperatures below 110°C the cooking rate is limited by the reaction rate of rice components with water; and at temperatures above 110°C it is limited by the rate of diffusion of water through the cooked layer toward the interface of uncooked core where the reaction occurs. The reaction rate constant and the diffusion coefficient of water were calculated by assuming the core model or shell-type model.
TL;DR: In this article, the authors measured the spin-lattice and spin-spin relaxation times of water adsorbed on sodium alginate, pectin, corn starch, casein and cellulose.
Abstract: Pulsed NMR was applied to measure the spin-lattice (T1) and the spin-spin (T1) relaxation times of the water adsorbed on sodium alginate, pectin, corn starch, casein and cellulose. T1 was determined by means of repeated 90°-90° pulse sequences and T2 by the spin-echo method. T1 relaxation time curves for all the samples studied showed simple exponential, i.e., single phase, behavior. Plots of T1 as a function of moisture content showed minima at 0.15–0.258 water/g dry matter; plots of T1 vs water activity (Aw) yielded minima at Aw of 0.65. T2 relaxation time curves for corn starch containing more than 0.56g water/g DM exhibited two-phase behavior, indicating the existence of two water fractions of different mobility. The amount of water in the bound fraction showed a remarkable consistency (0.194 ± 0.011g water/g DM) among six samples of high moisture content. T2 was found to increase with moisture content for all the macromolecules. Cellulose showed exceptionally long T2 values compared to the other materials at the same moisture content, whereas pectin and sodium alginate showed short T2 values. These results indicated that T2 value is a measure of strength of water binding. Break points were observed in the T2-moisture curve. The moisture contents at these points corresponded to the bound water content determined by freezing and to the equilibrium moisture content at Aw of 0.9. T2 increased exponentially with Aw.
TL;DR: In this article, an intermediate moisture model food system containing casein, glucose, glycerol, oil, microcrystalline cellulose and water, was used to study nonenzymatic browning.
Abstract: An intermediate moisture model food system containing casein, glucose, glycerol, oil, microcrystalline cellulose and water, was used to study nonenzymatic browning. The initial molar ratio of glucose to available lysine was varied from one-half to five. The model food system samples were prepared to 0.52 water activity and were stored in sealed cans at 45°C and analyzed periodically. The browning was followed by determining pigment accumulation, glucose utilization, and loss in FDNB-available lysine. The rate of pigment formation followed zero order kinetics after an initial short induction period. This rate increased linearly as the initial molar ratio of glucose to available lysine increased from one-half to three. Above this ratio the rate did not change. The initial rate of glucose utilization and available lysine loss obeyed first order kinetics, and increased as the initial molar ratio of glucose to available lysine increased from one-half to five. This work shows that in the presence of glycerol, the initial condensation reaction is not the rate controlling step for pigment production.
TL;DR: Isolation of this organism was more frequent after 28 days of storage under vacuum conditions than under nonvacuum conditions (leaker packages), and a higher incidence of isolates was obtained from cuts packaged under high vacuum conditions.
Abstract: Characteristics are presented for Yersiniu enterocoliticu-like organisms isolated from vacuum-packaged beef and lamb stored for 21-35 days at l-3°C. Isolation of this organism was more frequent after 28 days of storage under vacuum conditions than under nonvacuum conditions (leaker packages). A higher incidence of isolates was obtained from cuts packaged under high vacuum conditions.
TL;DR: The results indicate that some of the differences in tenderness produced by HT treatments are possibly associated with the increased level of free lysosomal enzymes during the first 12 hr postmortem, indicating that differences caused by high temperature conditioning take place very early postmortem and that differences in enzyme activities are not detectable at later postmortem times.
Abstract: The control (C) side of 23 animals was placed in a 2°C chill room at 1 hr postmortem, while the other side was high temperature cdnditioned (HT) at approximately 22°C for 4 hr postmortem, at 12°C for an additional 8 hr and was then placed in the 2°C chill room. The activity of cathepsin C and β-glucuronidase was measured on the nuclear, micro somal, and unsedimentable fractions at 12, 18 and 24 hr postmortem in order to determine the amount of sedimentable and free enzyme activity at these postmortem times. High temperature conditioning enhances the disruption of the lysosomal membrane as evidenced by a significant increase in percent of free enzyme activity at 12 hr postmortem for both cathepsin C and β-glucuronidase. There was also a significant decrease in total activity for both enzymes of the HT group at 12 hr postmortem due to autolysis of the free enzyme. These differences were not present at 18 and 24 hr postmortem (except for decreased total activity of cathepsin C at 18 hr), indicating that differences caused by high temperature conditioning take place very early postmortem and that the differences in enzyme activities are not detectable at later postmortem times. These results indicate that some of the differences in tenderness produced by HT treatments are possibly associated with the increased level of free lysosomal enzymes during the first 12 hr postmortem.
TL;DR: The factors affecting postharvest color losses in Concord grapes were investigated in this paper, with emphasis on the extraction, partial purification and characterization of naturally occurring enzymes that may be involved.
Abstract: The factors affecting postharvest color losses in Concord grapes were investigated, with emphasis on the extraction, partial purification and characterization of naturally occurring enzymes that may be involved. Color losses were accelerated in Concord juice by the crude enzyme extracted from the grapes. Catechol was oxidized more rapidly than other o-dihydroxyphenols, although pyrogallol, caffeic acid and dl-DOPA were good substrates for the crude polyphenoloxidase (PPO). The optimum activity was in the pH range 5.9–6.3 and at temperatures 25–30°C. Kinetic data for the crude enzyme showed a Michaelis constant of 67 mM of catechol at pH 6.0. Effective inhibitors were Na2S2 O5, dithiothreitol, phenylhydrazine, cysteine and others. Peroxidase (PRO) activity of the crude extract was very low in ripe Concord grapes. Anthocyanin pigment degradation by the crude enzyme extract was dependent on maturity of the grapes. The most rapid degradation of pigment occurred when crude enzyme from ripe grapes was added.
TL;DR: In this paper, the authors studied the kinetics of pigment production, glucose utilization and loss of DNP-available lysine in an intermediate moisture food (IMF) system.
Abstract: Maillard browning is one of the main chemical reactions causing deterioration and shortening shelf life of intermediate moisture food (IMF) systems. The purpose of this research was to study Maillard browning in an IMF model system containing casein, glucose and the liquid humectant glycerol. The kinetics of pigment production, glucose utilization and loss of DNP-available lysine were studied as a function of temperature, moisture content and water activity. It was found that the factors which control reactant (glucose and available lysine) utilization also control end-product (brown pigment) accumulation. The rate of the Maillard browning pigment production, after an initial induction period, follows zero order kinetics. The initial loss rate of both glucose and available lysine, however, follows first order kinetics. Exceedingly large nutritional (available lysine) losses occur before brown discoloration is appreciable. Slightly greater than one mole of glucose reacts per mole of lysine made unavailable. Based on this, nutritional losses may be relatively easily estimated by monitoring the loss of specific reducing sugars. The Maillard browning reaction proceeds 33 times faster at 45°C than at 2S°C, with the maximum rate occurring at 0.4–0.5 aw. This is an aw range considerably lower than the 0.65–0.75 aw range usually found for maximum browning in dehydrated foods. The downward shift in the aw maximum for browning is because glycerol being liquid has water-like properties and increases reactant mobility and/or solubility at aw's below which most water soluble reactions occur very slowly.
TL;DR: Succinylated proteins yielded functionality slightly but significantly superior to that of acetylated proteins, and the performance of enzyme-modified acylated fish protein derivatives in food systems is discussed.
Abstract: Enzymemodified acylated protein derivatives were prepared with succinic and acetic anhydrides from washed fish muscle and were evaluted for their functionality. The degree of acylation and of hydrolysis by bromelain was studied to determine how these variables affect functionality of the protein. The degree of acylation was determined by measuring available epsilon amino groups of lysine. Susceptibility to hydrolysis was determined by treating with bromelain at different ratios of bromelain to substrate. The functional properties studied were emulsifying activity, emulsifying capacity, gelation, water absorption, aeration, and foam stability. These functional properties increased until 43–59% of the free amino groups were acylated. Further acylation had no significant effect. Hydrolysis of the acylated protein slightly lowered the emulsifying, gelation, and water absorption properties, but increased the aeration capacity of both the acetylated and succinylated proteins and the foam stability of the latter. The succinylated proteins displayed functional properties similar to those of the acetylated proteins. Succinylated proteins, however, yielded functionality slightly but significantly superior to that of acetylated proteins. The performance of enzyme-modified acylated fish protein derivatives in food systems is also discussed.
TL;DR: In this paper, a comparison between Halsey's equation and Henderson's classical one was made between 220 food isotherms, comprising 69 different materials, were utilized to compare both equations.
Abstract: A multilayer adsorption equation, originally developed for physical adsorption on nonuniform surfaces, is used to describe the water sorption behavior of a great variety of foods and food components. Characteristic parameters of the sorption equation, for each of the products tested, were computed. A comparison was made between Halsey's equation and Henderson's classical one. Literature data for 220 food isotherms, comprising 69 different materials, were utilized to compare both equations. It was found that in most cases Halsey's equation has a better fit than Henderson's.
TL;DR: The effect of 20 combinations of salt and sodium tripolyphosphate (STP) on restructured pork were studied in this paper, where the effect of different levels of STP was evaluated.
Abstract: The effect of 20 combinations of salt and sodium tripolyphosphate (STP) on restructured pork were studied. Added salt increased TBA values, packaging loss, improved cooked color, aroma, flavor and eating texture and decreased cooking loss and raw color. Increase in STP decreased cooking loss and increased TBA values, packaging loss, raw color and juiciness. Synergism between salt and STP was shown for most traits studied. Storage increased TBA values, water-holding capacity and juiciness rating and decreased cooking loss, raw color, cooked color, aroma, flavor and eating texture. Among the 20 combination levels, 0.75% salt and 0.125% STP were the most desirable for producing restructured pork.
TL;DR: In this paper, the presence of α-linked galactose residues and β-linked mannose residues in coconuts and mannan were observed. But the results showed that mannans, almost absent in very immature kernel, increased with maturation and the water soluble galactomannan decreased with maturity.
Abstract: Polysaccharides in the kernel of coconuts were isolated, characterized and quantitated. At all stages of maturation, galactomannans and cellulose were present whereas mannans, almost absent in very immature kernel, increased with maturation. The water soluble galactomannan decreased with maturity. It was 0.1% in mature fresh kernel. The 4% NaOH extractable galactomannans reached a maximum value at an intermediate stage of maturation, whereas the 17% NaOH extractable galactomannans and the cellulose components steadily increased. The galactomannans always predominated and formed 61% of the total polysaccharides in the mature kernel, followed by mannans (26%) and cellulose (13%). The presence of α-linked galactose residues in galactomannan and of β-linked mannose residues in galactomannan and mannan were observed.
TL;DR: In this paper, the dissolution of nitrogen and phosphorus containing substances from defatted rapeseed, and the subsequent precipitation of these substances by acid was studied, and it was found that dissolution of the substances of interest varied in a complicated manner with the pH of extraction.
Abstract: The dissolution of nitrogen and phosphorus containing substances from defatted rapeseed, and the subsequent precipitation of these substances by acid was studied. The dissolution of the substances of interest was found to vary in a complicated manner with the pH of extraction. This was especially true for the dissolution of inositol hexaphosphoric acid (phytic acid) and the other phosphorus containing substances. The presence of phytic acid in the protein extracts strongly affected the nitrogen recovery, the useful pH range for precipitation and the dry matter content of the precipitates. These effects were different with extracts prepared at different pH values. With an extract prepared at pH 11.1, addition of sodium phytate increased the yield from about 35 to 75% of the extracted nitrogen and the dry substance content of the precipitate from 16 to 33%.
TL;DR: In this article, the results from time/temperature exposure studies on thin slices of meat were obtained when applying these data to calculate moisture profiles in roasts from known temperature profiles.
Abstract: Samples of semimembranosus muscles were oven roasted at 175°C, and 225°C from initial temperatures of −20° and +S°C. During heating temperature profiles were determined as a function of heating time. On duplicate samples the corresponding moisture and fat content profiles were determined for a number of heating times. Moisture and temperature profiles were found to be inversely related to each other, with temperature minimum and moisture maximum occurring near the sample center. For fat content no important trend was seen. Heating time was shorter and yield lower at 225°C than at 175°C, and cooking time increased by some 50% when cooking directly from the frozen state. Up to 65-70°C weight loss appears to occur almost entirely by evaporation from a wet surface, the surface temperature being determined by the wet bulb temperature of the oven atmosphere. Also, above 65°C weight loss by liquid drip becomes significant. The results from time/ temperature exposure studies on thin slices of meat showed that temperature is more important than time to drip loss, and surprisingly good agreement with experimental profiles was obtained when applying these data to calculate moisture profiles in roasts from known temperature profiles. For temperature calculations both Hottel diagrams and a simple mathematical model were used with promising results. These findings should help clarify the determining factors in oven roasting of meat, and point to means of controlling and optimizing cooking conditions with regard to yield and cooking time.
TL;DR: In this paper, a study was done to characterize the changes that occur during refrigerated storage of six salad vegetables individually and in a mixture, and the results showed that the vegetables were invariably poorer in organoleptic quality.
Abstract: This study was done to characterize the changes that occur during refrigerated storage of six salad vegetables individually and in a mixture. Salad-cut and intact lettuce, carrot, celery, radish, green onion and endive, and a salad mixture were stored at 4.4°C in packages made from a film having low gas permeability. Respiration of individual vegetables during storage showed two patterns: carrot and celery respired throughout the storage time while respirations by the others was halted after a few days. Respiration of cut vegetables exceeded that of intact. Total plate counts (TPC) for intact vegetables in storage increased slower than for cut vegetables; lettuce and endive showed higher TPC than the others. The cut vegetables were invariably poorer in organoleptic quality. Mixed vegetable salads were sealed with either air or an atmosphere containing 10.5% CO2, 2.25% O2. After 2-wk storage, organoleptic evaluation indicated that the chemical treatments were generally of no value and in some cases were even detrimental but the modified initial headspace was beneficial.
TL;DR: In this article, it was found that the application of high pressure to homogenates of meat in saline solution could increase water-holding capacity and promote the solubilization of proteins.
Abstract: In an earlier study it was found that the application of high pressure to homogenates of meat in saline solution could increase water-holding capacity and promote the solubilization of proteins. These studies have now been extended to myofibrils prepared from sheep semimembrano-sus muscle. The amount of protein solubilized by pressurization was found to be dependent on (1) temperature, generally being greater at 0°C than at 30°C; (2) the nature and the concentration of the salt; and (3) the pH. SDS gel electrophoresis indicated that solubilization of all the major constituent proteins of the myofibril could be promoted. It is suggested that the imidazole group is implicated in the pressure solubilization effect.
TL;DR: The changes in enzyme activity occurring during the ripening of strawberry fruit on the plant and the development of senescence after picking have been studied in this article, where Pectinesterase is found to increase from the green to early ripe stages but to decrease during the senescent “overripe” stage.
Abstract: The changes in enzyme activity occurring during the ripening of strawberry fruit on the plant and the development of senescence after picking have been studied. Pectinesterase is found to increase from the green to early ripe stages but to decrease during the senescent “overripe” stage. Polygalacturonase and polymethylgalacturonase activity were not found. A Cx-type cellulolytic activity was observed in ripe fruit and increases in the “over-ripe” fruit. These observations tie used to provide a possible explanation for the loss of firmness after strawberry fruit has been picked and becomes senescent.
TL;DR: A review of the available literature on crispness appears to be general agreement on the layman's use of the word crisp, however, the term has not been adequately defined as discussed by the authors.
Abstract: From a review of the available literature on crispness there appears to be general agreement on the layman's use of the word crisp. However, the term has not been adequately defined. Several instrumental methods for measuring the crispness of a product have been developed. Although these objective methods may serve as indicators in a single commodity, they fail to indicate crispness in a variety of both wet-crisp and dry-crisp foods. These instrumental analyses are likely measuring parameters that change under the same conditions that cause changes in the true characteristic of crispness.
TL;DR: In this article, the effect of heat treatment on a model protein, sperm whale myoglobin, at various water contents has been investigated at neutral pH, ranging from solid preparations of 3% to dilute solutions of 99.6% water content.
Abstract: The effect of heat treatment on a model protein, sperm whale myoglobin, at various water contents has been investigated at neutral pH. Samples ranging from solid preparations of 3% water content to dilute solutions of 99.6% water content have been examined. Differential scanning calorimetry (DSC) has been used for the heat treatments as well as for analyzing the effect of the heat treatments on the protein samples. At water contents below 30% only a certain fraction of the heat-treated protein sample underwent irreversible transitions. This fraction of the protein sample increased linearly with the amount of water present during the heat treatment. Above 30% water content the entire protein sample underwent irreversible transitions. The heating rate was shown to influence the transition temperature as well as the apparent transition heat. Possible applications in food technology and food processing of the DSC technique used are discussed.