Showing papers in "Journal of Food Science in 1986"
TL;DR: In this paper, a HPLC method was developed for separation and quantitative determination of inositol tri-, tetra-, penta-, and hexaphosphates, and compared to phytate determinations by two iron precipitation methods.
Abstract: A HPLC method was developed for separation and quantitative determination of inositol tri-, tetra-, penta-, and hexaphosphates. The method included extraction of inositol phosphates with HCI, separation of the inositol phosphates from the crude extract by ion-exchange chromatography, and ion-pair C18 reverse phase HPLC analysis using formic acid/methanol and tetrabutylammonium hydroxide in the mobile phase. The inositol 3–6 phosphates of raw and extruded bran, soy flour, and intestinal contents were determined by HPLC and compared to phytate determinations by two iron precipitation methods. Inositol 3–5 phosphates were found in extruded products and intestinal contents. The HPLC method was rapid and gave reproducible values, which differed from those obtained by the precipitation methods in some samples.
321 citations
TL;DR: In this paper, the color development during potato frying was studied, and both amino acids and reducing sugars participated in the colour development of potato during frying, with the amount of reducing sugars being the limiting factor.
Abstract: Color development during potato frying was studied. Increments of reducing sugars led to increase in color of fried potatoes. For L (luminosity) between 60–51, corresponding to a reducing sugar content of 120–140 mg %, an acceptable color was obtained. Both amino acids and reducing sugars participated in the color development of potato during frying, with the amount of reducing sugars being the limiting factor. Fructose yielded the highest browning followed by glucose. Sucrose addition caused practically no change in the final color of the fried potato. At low content of reducing sugars the reaction followed first-order kinetics, the activation energy, Ea, being equal to 31 Kcal mol-1.
203 citations
TL;DR: The water adsorption isotherms of Sultana raisins were determined using the static method of saturated salt solutions at 20°, 25°, 30°, and 35°C as mentioned in this paper.
Abstract: The water adsorption isotherms of Sultana raisins were determined using the static method of saturated salt solutions at 20°, 25°, 30°, and 35°C. The equilibrium moisture content at water activities up to 0.70 decreased as the temperature was increased from 20° to 35°C. At higher water activities the moisture content increased sharply as the temperature was increased, resulting in crossing of the isotherm curves. This behavior is attributed to the increased solubility of fruit sugars at higher temperatures. The experimental data were fitted well with the 3-parameter GAB and Halsey equations, and best with the 5-parameter D'Arcy-Watt equation. The thermodynamic implications are discussed.
194 citations
TL;DR: Significant varietal differences were observed in the contents of phytic acid, saponin and trypsin inhibitor activity of four varieties of Moth bean (Vigna aconitifolia Jacq.). Tannins and lectins were absent as discussed by the authors.
Abstract: Significant varietal differences were observed in the contents of phytic acid, saponin and trypsin inhibitor activity of four varieties of Moth bean (Vigna aconitifolia Jacq.). Tannins and lectins were absent. The dry seeds were given different treatments including soaking, sprouting and cooking and the changes in the level of the antinutritional factors were estimated. Soaking the seeds in plain water and mineral salt solution for 12 hr decreased phytic acid to the maximum (46–50%) whereas sprouting for 60 hr had the most pronounced saponin lowering effect (4466%). The other methods of processing were less effective in reducing the levels of these antinutritional factors. The processing methods involving heat treatment almost eliminated trypsin inhibitor activity while soaking and germination partly removed the activity.
175 citations
TL;DR: In this paper, the effects of four widely employed "antioxidants" on iron-mediated hydroxyl radical formation and lipid peroxidation were studied in aqueous model systems.
Abstract: The effects of four widely employed “antioxidants” on iron-mediated hydroxyl radical formation and lipid peroxidation were studied in aqueous model systems. Iron and copper served as catalysts for the reactions which oxidized ascorbic acid and alpha-tocopherol and reduced oxygen. Ferrous ion spontaneously reduced oxygen to O−2 (su-peroxide anion radical) which led to OH (hydroxyl radical) and H2O2 generation and lipid peroxidation. Precipitation or sequestration of iron greatly depressed these oxidative events. Complexation by EDTA and citric acid, however, formed catalytically active iron chelates. The concomitant increase in iron solubility explained the substantial enhancement of iron-driven redox reactions by EDTA and citric acid.
158 citations
TL;DR: In this article, the nutritional and oil characteristics of pumpkin and melon seeds were investigated on a dry basis, and the data obtained for the two seeds, respectively, were: crude oil 45.4 and 37.8%; crude protein, 32.3 and 25.2%; crude fiber, 12.1 and 15.4%; and ash, 4.65 and 3.85%. Food energy values were 2.83 and 2.59 MJ/100g, respectively.
Abstract: Nutritional and oil characteristics of pumpkin and melon seeds were investigated. On a dry basis, the data obtained for the two seeds, respectively, were: crude oil 45.4 and 37.8%; crude protein, 32.3 and 25.2%; crude fiber, 12.1 and 15.4%; and ash, 4.65 and 3.85%. Food energy values were 2.83 and 2.59 MJ/100g, respectively. The seeds were found to have considerable amounts of essential minerals (K, Ca, Mg, Fe, Cu, Zn, and P). The defatted flour of the pumpkin and melon seeds contained, respectively: crude protein, 55.4 and 39.4%; crude fiber, 28.1 and 24.7%; and ash, 7.23 and 6.18%. The major fatty acid of the oils was linoleic (18:2) at concentrations of 43.1 and 64.6%, followed by oleic (18:1), 37.8 and 20.1%, respectively.
157 citations
TL;DR: In this article, the effect of different initial dissolved oxygen concentrations (0.41, 1.44, and 3.74 mg/L) on rate of deteriorative quality changes [ascorbic acid degradation, browning, hydroxymethylfurfural (HMF) and furfural production] in lemon juice stored at 36°C was investigated.
Abstract: The effect of different initial dissolved oxygen concentrations (0.41, 1.44, and 3.74 mg/L) on rate of deteriorative quality changes [ascorbic acid degradation, browning, hydroxymethylfurfural (HMF) and furfural production) in lemon juice stored at 36°C was investigated. No significant effects on rate of ascorbic acid degradation and furfural formation could be attributed to the different oxygen levels. Degradation of ascorbic acid appeared to be predominantly anaerobic. Lag period before browning increased depended on oxygen level. Zero-, first- and second-order kinetic models were fitted to various degradative reactions occurring in lemon juice during storage. Highly significant correlations were obtained between browning index, HMF, and furfural formation, suggesting that all three would be suitable as chemical indices of storage temperature abuse in lemon juices.
155 citations
TL;DR: Carrots, beet greens, spinach, swiss chard and sweet potatoes had the most vitamin A activity and beta-Carotene was the most prevalent carotenoid.
Abstract: A study was conducted to determine alpha- and beta-carotene and beta-cryptoxanthin in twenty-two fruits and vegetables. Foods were obtained from wholesale distributors from five locations throughout the United States (Los Angeles, Dallas, Chicago, Miami, and Boston) three times during a year (November, March, and July). Mean vitamin A activity in retinol equivalents (RE) of each food along with average values for the individual carotenoids (μg/100g) are given. beta-Carotene was the most prevalent carotenoid. Carrots, beet greens, spinach, swiss chard and sweet potatoes had the most vitamin A activity. Analysis of variance indicated that there were no significant differences among either locations or time of analysis. A comparison was made between the new values and the ones listed in USDA Handbook No. 8 and revised Handbook No. 8–9. There were differences between the old and new values in 14 of the 22 fruits and vegetables analyzed.
151 citations
TL;DR: In this paper, the effect of low-calcium-requiring calcium-activated factor (μM CAF) on the myofibrils under varying pH at 5°C and 25°C was examined spectrophotometrically, electrophoretically, and microscopically (phase microscopy and transmission electron microscopy).
Abstract: The effect of low-calcium-requiring calcium-activated factor (μM CAF) on the myofibrils under varying pH at 5°C and 25°C was examined spectrophotometrically (absorbance at 278 nm), electrophoretically (sodium dodecyl sulfate polyacrylamide gel electrophoresis), and microscopically (phase microscopy and transmission electron microscopy). Results indicated that at conditions similar to those of postmortem storage (i.e., pH 5.5–5.8 and 5°C), μM CAF retained 24–28% of its maximum activity (pH 7.5 at 25°C). This 24–28% of maximum activity was sufficient to reproduce most of the known changes associated with the tenderization process during postmortem aging. It was concluded that because of the activity of μM CAF under postmortem conditions, it seems reasonable to suggest that μM CAF may be responsible, in part, for some of the postmortem changes observed.
148 citations
TL;DR: In this article, the effects of ozone on the quality of poultry chiller water and broiler carcasses were evaluated in a pilot plant size water recirculating chicken chiller and the microbial counts of ozone treated carcasses stored at 4.4°C were consistently lower than carcasses chilled under nonozonated conditions.
Abstract: The effects of ozone on the quality of poultry chiller water and broiler carcasses were evaluated in a pilot plant size water recirculating poultry chiller. The microbial counts of ozone treated carcasses stored at 4.4°C were consistently lower than carcasses chilled under nonozonated conditions. Greater than 99% of all microorganisms washed from the carcasses were destroyed by the residual ozone in addition to significant reductions of one third in the chemical oxygen demand (COD) and a significant increase in light transmission (500 nm) of the treated process water. No significant carcass skin color losses, lipid oxidation, or off flavors resulted from ozone contact.
146 citations
TL;DR: In this article, the effect of storage on apple juice concentrate was determined by following changes in composition during a period of 111 days at 37°C. Results showed that storage caused an 87% loss in the total free amino acids, which was mostly due to decreases in glutamic acid, asparagine and aspartic acid.
Abstract: The effect of storage on apple juice concentrate was determined by following changes in composition during a period of 111 days at 37°C. Results showed that storage caused an 87% loss in the total free amino acids, which was mostly due to decreases in glutamic acid, asparagine and aspartic acid. The forml titration method was inadequate for determining the amino compounds involved in Maillard-type reactions. Sucrose was hydrolyzed under these conditions at a rate corresponding to a fist order process. The reducing sugars increased at a rate determined by the inversion of sucrose; no consumption attributable to browning reaction was detected. Reduction of organic acids was 9% while apparent phenolic compounds increased from 0.149 to 0.215 g/100g. A maximum accumulation of HMF was observed after 100 days of storage.
TL;DR: This paper showed that high pH muscles exhibited an extensive degradation of Z-lines, whereas low pH muscles showed a preferential degradation of M-lines and myosin heavy chains and intermediate pH muscles did not show much degradation of muscle proteins.
Abstract: Bovine longissimus muscles with postmortem pH in the range 5.5 - 7.0 were subjected to different postmortem temperatures of 1°, 4°, 25° and 37°C. Intact beef sides with different postmortem pH were also subjected to two different environmental temperatures of 1° and 25°C. High pH muscles exhibited an extensive degradation of Z-lines, whereas low pH muscles showed a preferential degradation of M-lines and myosin heavy chains. Intermediate pH muscles did not show much degradation of muscle proteins, resulting in tougher meat than either low or high pH muscles. High postmortem temperatures enhanced the degradation of muscle proteins in excised and incubated muscle strips, but the delayed chilling of intact beef sides at 25°C for 8-hr did not affect either the structural changes or meat tenderness.
TL;DR: In this paper, the effects of adding Iota-carrageenan, kappa-carrageenan and guar gum to low-fat, high moisture meat batters were investigated.
Abstract: The effects of adding Iota-carrageenan, kappa-carrageenan, guar gum, locust bean gum, xanthan gum, methylcellulose, and a locust bean gum/kappa carrageenan mixture to low-fat, high moisture meat batters were investigated. The methylcellulose treatment showed an increase in weight losses between 60° and 70°C, while other treatments remained similar throughout heating. Xanthan gum and guar gum at 0.2% altered textural parameters as determined by texture profile analysis. Increasing the concentration of xanthan gum decreased batter hardness without affecting batter stability. Sensory evaluation indicated that low-fat frankfurters (11–12% fat) were as acceptable as control frankfurters (27% fat).
TL;DR: In this article, the fat and moisture values for beef longissimus steaks (trimmed completely of all subcutaneous fat, epimysium, and peripheral muscles) from 518 steer and heifer carcasses of A and B maturity over a wide range in marbling were analyzed.
Abstract: Percentage fat and moisture values for beef longissimus steaks (trimmed completely of all subcutaneous fat, epimysium, and peripheral muscles) from 518 steer and heifer carcasses of A and B maturity over a wide range in marbling were as follows: Moderately Abundant = 10.42 and 68.14, Slightly Abundant = 8.56 and 69.56, Moderate = 7.34 and 70.35, Modest = 5.97 and 71.35, Small = 4.99 and 72.36, Slight = 3.43 and 73.61, Traces = 2.48 and 74.29, and Practically Devoid = 1.77 and 75.37.
TL;DR: In this paper, the isosteric heat and entropy of water sorption of food products were calculated from sorption isotherms previously reported by other researchers, and a two-parameter sorption equation was derived, which took into account the effect of temperature on water sarsotherms.
Abstract: The isosteric heat and entropy of water sorption of food products were calculated from sorption isotherms previously reported by other researchers. The plot of the isosteric heat against entropy satisifed the enthalpy-entropy compensation. This relationship was used to derive a two-parameter sorption equation which took into account the effect of temperature on water sorption isotherms of food products.
TL;DR: In this paper, 12 treatment combinations including three fat levels, two internal endpoint temperatures, and two storage periods for ground beef patties were studied, and the results showed that no differences in cholesterol content could be attributed to fat content of raw product; therefore, choosing low fat ground beef to lower cholesterol may not be justified.
Abstract: Twelve treatment combinations including three fat levels, two internal endpoint temperatures, and two storage periods for ground beef patties were studied. Quality and sensory attributes as well as cholesterol content were evaluated. As fat level increased in raw patties, cholesterol content, drip and total cook loss, fat and cholesterol content of cook drip increased whereas red color intensity and evaporative losses decreased. Cholesterol content, evaporative and total losses, and beef-flavor intensity increased with higher internal endpoint temperature. Red color intensity of raw patties and cholesterol content of raw and cooked patties decreased with storage. No differences in cholesterol content could be attributed to fat content of raw product; therefore, choosing low fat ground beef to lower cholesterol may not be justified.
TL;DR: Myosin, fibrinogen and albumin gels were formed by heating in pH 6.0 phosphate buffer at three heating rates andTurbidity (A660nm) and solubility decreased as temperatures preceding the development of gel strength.
Abstract: Myosin, fibrinogen and albumin gels were formed by heating in pH 6.0 phosphate buffer at three heating rates. Turbidity (A660nm) and solubility were monitored along with gel strength, as measured with an annular pump. Myosin and fibrinogen suspensions became turbid and solubility decreased as temperatures preceding the development of gel strength. Linearly increasing heating rates of 12°C/hr and 50°C/hr produced the strongest myosin and fibrinogen gels at 70°C, whereas albumin gels formed at 95°C by heating at 12°C/hr or constant heating for 20 min did not differ in strength.
TL;DR: Ascospores of three strains each of Talaromyces flavus, Neosartorya fischeri and Byssochlamys fulva/nivea were analyzed for resistance to thermal inactivation in five fruit-based products and the type of fruit product did not appear to substantially influence rates of thermal in activation.
Abstract: Ascospores of three strains each of Talaromyces flavus, Neosartorya fischeri and Byssochlamys fulva/nivea were analyzed for resistance to thermal inactivation in five fruit-based (blueberry, cherry, peach, raspberry and strawberry) products. D91°C values for two strains of T. flavus ranged from 2.9–5.4 min; D88°C values ranged from 7.1–22.3 min. Ascospores of N. fischeri were somewhat less heat resistant; D91°C values were < 2.0 min and D88°C were 4.2–16.2 min. Ascospores of Byssochlamys spp. were considerably less heat resistant. The type of fruit product did not appear to substantially influence rates of thermal inactivation. No heat-resistant ascospores of T. flavus or N. fischeri, i.e., ascospores capable of surviving 15 min at 75°C, were formed on fruit products stored at 10°C for 137 days. However, T. flavus and N. fischeri formed ascospores on cherry substrate stored at 25°C within 65 and 137 days, respectively, that survived 15 min at 88°C.
TL;DR: Formation of extra protein bands of sulfite inhibited purified pear PPO fractions on gel electrophoresis was demonstrated, and other evidence suggested that the major mode of direct irreversible inhibition of PPO was modification of the protein structure, with retention of its molecular unity.
Abstract: When polyphenoloxidase (PPO) was exposed to sulfite prior to susbstrate addition, inhibition was irreversible. Trials to regenerate PPO activity, using extensive dialysis, column chromatography, and addition of copper salts were not successful. Increased concentrations of sulfite and pH levels less than 5 enhanced the inhibition of PPO by sulfite. At pH 4, concentrations greater than 0.04 mg/mL completely inhibited 1,000 units of PPO activity almost instantaneously. This suggested that the HSO3- molecule was the main component in the sulfite system inhibiting PPO. Column chromatography, extensive dialysis, and gel electrophoresis did not demonstrate 35SO2 bound to purified pear PPO protein. Formation of extra protein bands of sulfite inhibited purified pear PPO fractions on gel electrophoresis was demonstrated. This and other evidence suggested that the major mode of direct irreversible inhibition of PPO was modification of the protein structure, with retention of its molecular unity.
TL;DR: In this article, a combined model was derived to describe the variation of viscosity with shear rate, concentration and temperature for aqueous dispersions of xanthan gum.
Abstract: Apparent viscosities of xanthan gum dispersions over shear rates of 0.5-3000~s’ were studied at concentrations of 0.05-I .OO% (w/w) and temperatures of 5-45”C. All dispersions were shear rate thinning nonNewtonian fluids described accurately by the power-law model. The logarithm of viscosity varied with the logarithm of concentration and the reciprocal of absolute temperature. A combined model was derived to describe the variation of viscosity with shear rate, concentration and temperature for aqueous dispersions of xanthan gum. D
TL;DR: The redness and hue in raw and baked salmon flesh and the redness in smoked salmon were correlated to the pigment concentration in raw salmon.
Abstract: Color of wild, astaxanthin pigmented, and farmed, canthaxanthin pigmented, Atlantic salmon (Salmon salar) was evaluated by spectroscopy and visual sensory analyses. A more yellow hue in farmed salmon color compared with wild salmon was found in acetone extracts of raw salmon flesh and by visual sensory analyses of raw, baked and smoked salmon flesh. With instrumental color analysis directly on raw flesh, no significant differences in color between wild and farmed salmon were found. The redness and hue in raw and baked salmon flesh and the redness in smoked salmon were correlated to the pigment concentration in raw salmon. The redness and hue in processed salmon were predictable from the redness and hue of raw flesh.
TL;DR: In this paper, a quantitative methodology was developed for evaluating thermal process schedules for low acid foods containing particulates of any shape, using finite element analysis to determine temperature distributions within particulate foods subjected to timevarying boundary conditions.
Abstract: A quantitative methodology was developed for evaluating thermal process schedules for low-acid foods containing particulates of any shape. The methodology uses finite element analysis to determine temperature distributions within particulate foods subjected to timevarying boundary conditions. Simulations were conducted to study the effects of particle size, residence time distributions within heat exchanger and holding tube, and convective heat transfer coefficients. Results indicate that all these factors have significant effects on the thermal process schedule required to achieve commercial sterility. For large particles, simulations indicate that little credit can be given for lethality within the heating section.
TL;DR: In this paper, the effects of cyclic freezing and thawing upon the quality of frozen surimi of two species were studied with respect to sol viscosity, sol rigidity changes during thermal processing and structural failure properties of the cooked gel.
Abstract: The effects of cyclic freezing and thawing upon the quality of frozen surimi of two species were studied with respect to sol viscosity, sol rigidity changes during thermal processing and structural failure properties of the cooked gel. A torsion test, used to determine the strength of gels subjected to different thermal histories, revealed that increasing the number of freeze-thaw cycles reduced the strength and deformability of both sand trout and Alaska pollack surimis. Continuous monitoring of sol rigidity during thermal processing showed little changes in thermal transition temperatures caused by freeze-thaw abuse for either surimi but shifts occurred in overall rigidity levels. Particularly dramatic changes were induced in the Alaska pollack rigidity thermogram. The rigidity thermograms of sand trout and Alaska pollack were significantly different, as were their responses to freeze-thaw abuse and low temperature (4°C and 40°C) pretreatments.
TL;DR: In this article, the chemical and functional properties of three precooked flours pre-pared from citric acid- and sodium bicarbonate-treated chickpeas were compared with those of raw chickpea and soybean flours.
Abstract: The chemical and functional properties of three precooked flours pre-pared from citric acid- and sodium bicarbonate-treated chickpeas were compared with those of raw chickpea and soybean flours. The nitrogen solubility and foaming capacity of the precooked flours were markedly reduced by processing. The acid-treated flours showed higher values of oil absorption and viscosity than the sodium bicarbonate-treated flour, but the latter had a higher bulk density. Even at 10% concentration, the acid-treated flour slurries manifested very low viscosities (about 11 centipoises). No significant difference was detected in the water absorption and gelation capacity of the precooked flours.
TL;DR: In this paper, the binding ability increased linearly with increasing ionic strength and pH until a maximum value was reached and then plateaued; approximately 80% of the increase in binding ability was due to an increase in ionic strengths and pH.
Abstract: Combinations of sodium chloride and five different phosphates were used to study the effect of phosphate type (chain lengths: 1.0–12.8), ionic strength (0.15–0.43), and pH (5.50–6.35) on the binding ability (cook yield and tensile strength) of restructured beef rolls. The results showed that binding ability increased linearly with increasing ionic strength and pH until a maximum value was reached and then plateaued; approximately 80% of the increase in binding ability was due to the increase in ionic strength and pH. Above an ionic strength of 0.15, the polyphosphates (chain length > 1.0) produced synergistic increases in binding ability with increasing ionic strength. The extent of the synergistic effect decreased linearly as the chain length of the phosphate increased.
TL;DR: In this paper, the conditions under which a high volume fraction of oil can be trapped in whey protein gels were studied, and the results showed that homogenization was the major factor to achieve gelation and the firmness of heat-induced gels increased with increasing emulsion fineness and homogeneity.
Abstract: The conditions under which a high volume fraction of oil can be trapped in whey protein gels were studied. Oil-in-water emulsions of whey protein and vegetable oil were subjected to heat treatment. Such emulsions, depending on their protein and oil content, on their pH and on the emulsification technique used, gelled or remained liquid. Homogenization was the major factor to achieve gelation and the firmness of heat-induced gels increased with increasing emulsion fineness and homogeneity. Emulsions with a high gelation capacity were characterized by a single droplet family of relatively narrow size distribution and a mean droplet diameter ranging from roughly 300–700 nanometers. The pH range suitable for gelation extended from 3.5–8.0.
TL;DR: In this paper, a new method for coconut oil extraction based on the enzymatic action of polygalacturonases, α-amylase and proteases on a diluted coconut paste was developed.
Abstract: A new method for coconut oil extraction based on the enzymatic action of polygalacturonases, α-amylase and proteases on a diluted coconut paste was developed. After reaction with enzymes, the solution was centrifuged resulting in three phases: the upper one containing a high quality coconut oil; the middle layer containing water; and the lower phase consisting of coconut meal which has been traditionally used in cattle feed. Eighty percent yields were obtained by this method which was advantageous from the energy point of view compared to the traditional process.
TL;DR: Reflectance and absorbance spectrophotometric studies on commercial and laboratory samples showed that the pigments responsible for a pink color defect sometimes observed in freshly cut surfaces of cooked turkey rolls were reduced hemochromes, possibly nicotinamide-denatured globin hemochemes, rather than nitrosyl pigments as mentioned in this paper.
Abstract: Reflectance and absorbance spectrophotometric studies on commercial and laboratory samples showed that the pigments responsible for a pink color defect sometimes observed in freshly cut surfaces of cooked turkey rolls were reduced hemochromes, possibly nicotinamide-denatured globin hemochromes, rather than nitrosyl pigments. Oxidation-reduction potential measurements of meat systems showed that hemochrome formation was promoted by reducing conditions and prevented by oxidizing conditions. All constituents necessary for the production of pink color defect were present in turkey meat. The variable most affecting its appearance was the redox potential of the meat.
TL;DR: In this paper, the effect of break temperature on changes in organic acids and sugars in canned juices made from VF145-7879 and UC 82B tomatoes was investigated by HPLC.
Abstract: The effect of break temperature on changes in organic acids and sugars in canned juices made from VF145-7879 and UC 82B tomatoes was investigated by HPLC. Oxalic, citric, galacturonic, malic and pyrrol- idonecarboxylic acids were shown to be present in the canned juices. Oxalic and galacturonic acids decreased as the break temperature increased. Fructose was present in slightly higher amounts than glucose. Break temperature did not cause significant changes in sugar content of the canned juices made from UC 82B tomatoes.
TL;DR: A dialysis cell was devised to study in vitro digestion of proteins and Nitrogenous material collected with the sodium phosphate buffer was analyzed without further fractionation for the direct measurement of hydrolysis kinetic or of protein digestibility.
Abstract: A dialysis cell was devised to study in vitro digestion of proteins. The inner reaction vessel (surrounded by a tubular membrane with molecular weight cutoff of 1000) was fixed into a cylindrical outer compartment where buffer circulation was provided. The dimensions of compartments, membranes and buffer flow rate were determined with labelled amino acids in order to ensure the most efficient diffusion pattern. For the digestion assay, casein was first hydrolyzed with pepsin (pH 1.9) for 30 min. The mixture was then made alkaline (pH 7.5) and poured into the dialysis tube with pancreatin. Nitrogenous material collected with the sodium phosphate buffer was analyzed without further fractionation for the direct measurement of hydrolysis kinetic or of protein digestibility.