Amount Of Available Lysine Research Articles

Effect of the Addition of Milk Protein Preparations on Selected Quality Parameters and Nutritional Characteristics of Kefir

The aim of this study was to evaluate the effect of the addition of various milk protein powder preparations (MPC-80, WPC-70, sweet whey, non-demineralized or demineralized whey, whey permeate, rennet casein, buttermilk) to selected quality parameters and digestibility of milk proteins in kefir. Kefir samples analyzed in the study were prepared under laboratory conditions with three industrial bacterial starter cultures. They were examined microbiologically (lactobacilli, lactococci, yeast) and for pH, total protein content, hardness, adhesiveness, water-holding capacity (WHC), and protein digestibility (using two in vitro methods along with the determination of the content of available lysine and glycine). The counts of lactococci and lactobacilli were estimated at levels above 7 and 6 log(CFU/mL), respectively. Yeast was not found in the kefir samples. The pH value of the samples was 4.4–5.2. The pH, hardness, adhesiveness, and WHC were dependent on the type of kefir starter culture and the type of milk protein powder added. Each protein preparation added increased the amount of available lysine and glycine. However, when converted for 1 g of kefir protein, the changes in the content of available lysine and glycine were variable and depended on both the milk protein powder and starter culture used.

Quality and nutritional properties of corn snacks enriched with nanofiltered whey powder

Corn snacks containing 0, 3, 5, and 10% of nanofiltered whey powder, obtained from the raw material of 12 and 14% moisture contents were analysed. Colour, texture, sensory properties, protein, available lysine, and acrylamide contents were determined in extrudates. When the whey powder content increased above 5%, the extrudate breaking force decreased and the colour became darker. The addition of 10% of whey powder resulted in lower scores for porosity, colour, taste, and overall desirability. Such a level of the addition caused a significant increase in protein and available lysine contents in extrudates, but unfortunately, the product had also significantly higher acrylamide content. In extrudates obtained from the raw material of 12% moisture the amount of acrylamide was higher and the amount of available lysine was lower than that in extrudates obtained from the raw material with 14% moisture content. From the nutritional point of view it is better to extrude the raw material of higher feed moisture with the addition of nanofiltered whey powder.

直火焼きにおける牛挽肉の性状と有効性リジン量の変化

直火焼きにおける牛挽肉の性状と有効性リジン量の変化

A comparative study on amino acid availability of moist heated canola meal for poultry vs. ruminants

The objectives of this work were to measure the effect of moist heat treatment of canola meal (CM) on AA availabilities in poultry relative to ruminants, and to determine whether CM heated to increase rumen escape of protein could be used for poultry. Four groups of nine cockerels were randomly assigned to one of four treatments: untreated CM (control), CM moist heated (127°C) for 15 min, 45 min, and 90 min. Bioavailabilities of AA in CM for poultry were determined using the force-fed rooster technique. The resulting true available AA (TAAA) values were then compared with small intestinal AA disappearance values which were determined in steers. In poultry, 15 min heat treatment had no negative effects ( P > 0.05) on the TAAA values of all essential AA except methionine, lysine, and threonine which were reduced ( P < 0.05). Prolonged heat treatment (90 min) reduced ( P < 0.05) the TAAA values of all essential AA. In terms of amounts of available AA (g kg −1 DM CM), 15 min heat treatment did not influence ( P > 0.05) available methionine, threonine, phenylalanine, tryptophan and arginine, and increased ( P < 0.05) amounts of available leucine, isoleucine, histidine, and valine. Amount of available lysine was reduced (P < 0.05) by 11.8 g kg −1 initial lysine. Nylon bag results with steers indicated that 15 min heat treatment maximized the ( P < 0.05) small intestinal disappearance of all the individual essential AA and, also, increased amounts of available AA. Supplementation of the 15 min moist heated CM with lysine would be required for CM intended for poultry.

Feeding Heat-Treated Full Fat Soybeans to Cows in Early Lactation

Forty-six multiparous Holstein cows were fed one of three total mixed diets from 15 to 119 d postpartum with alfalfa silage as the only forage. Each diet contained 50% forage and 50% concentrate on a DM basis. Diets were formulated to be isonitrogenous by replacing corn and solvent soybean meal with raw soybeans or heat-treated soybeans. The proportion of protein supplement in the diet on a DM basis was 10% soybean meal, 13% raw soybeans, or 13% heat-treated soybeans. The soybeans were heat-treated to maximize the amount of available lysine passing to the small intestine. The soybean meal diet was fed to all cows during wk 1 and 2 postpartum for covariate adjustment of DMI and milk production. Intake of DM was similar across treatments. Feeding heat-treated soybeans supported more milk (4.5 kg/d), 3.5% FCM (4.0 kg/d), and milk protein (.09 kg/d) than soybean meal or raw soybeans. Milk fat percentage was not altered by treatments. However, milk protein percentage was depressed in cows fed heat-treated soybeans compared with soybean meal (2.85 vs. 2.99%, respectively). Milk production response cows fed proply heat-trated soybeans of compared with soybean meal with alfalfa silage as the sole forage is thought to be related primarily to improved supply of undegraded intake protein.

Thermal inactivation of lectins and trypsin inhibitor activity during steam processing of dry beans (Phaseolus vulgaris) and effects on protein quality

AbstractThe effect of steam treatment on the protein quality and antinutritional factors in beans (Phaseolus vulgaris L) have been evaluated. The thermal inactivation of total and functional lectins and trypsin inhibitor activity as well as total and available lysine during steam treatment at 102, 119 and 136°C can be described by first order reaction kinetics. Inactivation of trypsin inhibitor factors occurred in two stages with different reaction rates, the initial stage having a higher rate of inactivation. The effect of steaming temperature on the rate constants can be predicted by an Arrhenius‐type relation.Part of the total lysine was lost on heating but the amount of available lysine was reduced to a greater extent. The results of the present investigation indicate that steam treatment at 119°C for 5 or 10 min seems to be a good compromise in terms of antinutritional factor inactivation and protein damage as measured by total and available lysine.

Elimination of Lactose Interference in the Determination of Available Lysine Using Fluorine-19 Nuclear Magnetic Resonance Spectroscopy

When the 19F nuclear magnetic resonance method for determining free ∈-amino groups of lysine residues in intact proteins is used on mixtures containing lactose, the amount of available lysine determined decreases with increasing lactose concentration. The reaction of lactose with lysine residues appears to be much more strongly promoted in dimethyl-sulfoxide than in aqueous environments as shown by comparable experiments in water. If the method is modified to remove lactose by dialysis prior to the reaction with S-ethyl trifluorothioacetate, the number of available ∈-amino groups determined equals that of the pure proteins. The modified method as tested with nonfat dry milk gives excellent agreement with results obtained from a Kakade-Liener method.

Digestibility of Modified Milk Proteins: Nutritional Implications

Chemical changes in the structure of several milk proteins were quantitated and the effects on digestibility evaluated using a number of in vitro techniques developed in our laboratory. An assay for digestibility was developed and standardized incorporating immobilized gastric, pancreatic, and intestinal mucosal proteinases and peptidases and thereby simulating in vivo digestion. The method displayed a direct relationship to digestibilities determined in human feeding studies. Various degrees of racemization were induced in a number of proteins and quantitated with the aid of a bioreactor containing coimmobilized D-amino acid oxidase and catalase. Digestibility values were directly related to the degree of racemization and to the amount of lysinoalanine. In a separate study of these proteins, various degrees of Maillard reaction were induced, and the available lysine was quantitated using the fluoro-metric o-phthalaldehyde method. Digestibility values determined for these modified proteins were also directly related to the amount of available lysine. A bioreactor containing various immobilized proteinases and peptidases catalyzed complete hydrolysis of a number of proteins including β-lactoglobulin. Because this method does not degrade residues such as tryptophan and methionine nor hydrolyze aldosyl lysine to give unmodified lysine, analysis of these hydrolysates yields more nutritionally meaningful chemical scores. In summary, these techniques appear to be useful for quantitating and monitoring changes in the structures of proteins resulting from processing and storage, which affect their nutritional quality.

In VitroEnzymatic Determination of the Protein Nutritional Value and the Amount of Available Lysine in Extruded Cereal-based Products

An in vitro method, using proteolytic enzymes for protein hydrolysis, was used to evaluate the effect of extrusion cooking on protein quality. The products studied were protein-enriched biscuits processed in a twin-screw extruder under different conditions. In the product processed at low temperature (170°C), the digestibility was comparable with that of the raw material. With increasing temperature (170 to 210°C), the in vitro availability of amino acids decreased. This decrease was most pronounced in the case of lysine, but the recovery of methionine, arginine, glycine, aspartic acid and aspargine was also affected. A loss of lysine, methionine and arginine could also be detected after acid hydrolysis. The total amount of lysine present in the raw material was not completely available, as judged from the in vitro assay as well as from balance experiments in rats. With increasing severity of heat treatment, the loss of biologically available lysine was more pronounced than the loss of total lysine. Howev...

In vitro enzymatic determination of the protein nutritional value and the amount of available lysine in extruded cereal-based products.

An in vitro method, using proteolytic enzymes for protein hydrolysis, was used to evaluate the effect of extrusion cooking on protein quality. The products studied were protein-enriched biscuits processed in a twin-screw extruder under different conditions. In the product processed at low temperature (170°C), the digestibility was comparable with that of the raw material. With increasing temperature (170 to 210°C), the in vitro availability of amino acids decreased. This decrease was most pronounced in the case of lysine, but the recovery of methionine, arginine, glycine, aspartic acid and aspargine was also affected. A loss of lysine, methionine and arginine could also be detected after acid hydrolysis. The total amount of lysine present in the raw material was not completely available, as judged from the in vitro assay as well as from balance experiments in rats. With increasing severity of heat treatment, the loss of biologically available lysine was more pronounced than the loss of total lysine. However, the loss of enzymatically available lysine was in good agreement with the results obtained in animal experiments. An increase in moisture content of the feed during processing, from 13 to 18%, improved the availability of lysine in particular.

Plasma amino acid response to single test meals in humans. VI. Determination of available lysine.

The plasma amino acid response to single test meals in young adults was used to determine the amount of physiologically available lysine in heat-treated milk samples. The plasma amino acid responses were evaluated as PAA ratios according to a modified calculation procedure based on the method proposed by Longenecker and Hause. The amount of available lysine was determined by two separate series of single-meal tests. In the first, a relationship was established between the plasma amino acid response (PAA ratio) and the dietary level of lysine (given as synthetic amino acid mixtures). This relationship could be described by linear regression (r = 0.90). This regression line was then used to quantitatively evaluate the lysine PAA ratios obtained from single test meals with heat-treated milk samples. The heat-treatment of the milk samples caused a marked reduction of the amount of physiologically available lysine. The quantitative estimates obtained by the present plasma amino acid technique were in good agreement with determinations of available lysine in the same milk samples based on rat bioassay and chemical analysis.

Factors Affecting the Determination of Available Lysine in Whey with 2,4,6-Trinitrobenzene Sulfonic Acid

Lactose in cheese whey interferes with the determination of biologically available lysine in whey proteins when the reagent 2,4,6-trinitrobenzene sulfonic acid is employed. Loss of the epsilon-TNP-derivative of lysine is dependent upon the amount of lactose hi the test material. The sample weight chosen for analysis also influences results with this reagent. The larger the sample of either pure protein or carbohydrate containing material, the smaller the amount of available lysine found. By careful selection of experimental conditions and by application of a correction formula for lactose interference, the available lysine in whey protein can be rapidly approximated with the 2,4,6-trinitrobenzene sulfonic acid method. Results compare favorably with those obtained by an established method.

Availability of essential amino acids from proteins. I. Beef serum albumin.

AbstractAvailable essential amino acids from beef serum albumin were determined microbiologically, after total enzymic hydrolysis of the protein by papain, leucine aminopeptidase and prolidase. Samples of pure beef serum albumin of different moisture content were heat‐treated with glucose at 90° or without it at 121°. In the enzymic digest of the protein, available essential amino acids were determined using Streptococcus faecalis, S. zymogenes and Lactobacillus arabinosus. The content of essential available amino acids was correlated with the degree of in vitro digestibility of heat‐treated albumin.The amount of lysine determined by Carpenter's method with fluordinitrobenzene did not correspond to the values found for lysine by microbiological analysis with S. faecalis. Lysine reactive with fluordinitrobenzene was found in the non‐digestible residue of the protein, so that the values obtained by the chemical method are probably higher than the actual amount of available lysine. The results for the trypsin digest of the albumin were similar by both methods. The availability of lysine as well as that of amino acids in general depended on the enzymic digestibility.

アミノ酸自動分析計による有効性リジンの定量

A chemical method for the determination of available lysine in protein based on the reactivity of dinitrofluorobenzen (FDNB) with free ε-amino group of lysine has been reported by CARPENTER. RAO et al. and NIELSEN et al. used the CARPENTER hydrolysis technique followed by ion-exchange chromatography to measure the available lysine directly. In this paper, the amount of available lysine was measured from the determination of total lysine and residual one of FDNB treatment by using an amino acid analyzer. The technique is seen to be convenient, and it gave more satisfactory results as compared with that obtained by the method of CARPENTER. The direct determination of ε-DNP-lysine by using amino acid analyzer was also described.

Lysine and Methionine Availability in Heated Casein-Glucose Mixtures

Abstract Mixtures of casein, glucose, and water (2:2:1) were autoclaved at 15 p.s.i. for 5, 10, 20, and 40 minutes and then freeze dried. The available lysine and methionine in the casein-glucose (C-G) mixtures were determined by chemical and bioassay techniques. There was a considerable decrease in the amount of available lysine (65—68%) and methionine (39—47%) in the samples antoclaved for 20 and 40 minutes. The gross protein values of C-G mixtures combined with basal diets deficient in lysine or methionine gave values for available lysine and methionine which agreed closely with those obtained by chemical and microbiological assays. Plasma lysine levels correlated well with the gross protein values (r = 0.99; n = 4) and dinitrofluorobenzene available lysine; however, the correlation between the plasma methionine levels and gross protein values was not as significant (r=0.75; n = 5). The results presented here show that it is possible to use plasma amino acid levels as an index of the nutritional availability of certain amino acids in foodstuffs.

Available lysine in meat and meat products

AbstractThe amount of available lysine in different sorts of beef and pork was determined and the relation between lysine and content of connective tissue was ascertained. The extent of reduction of the available lysine on heat processing depends on the time of heating and the proportion of meat and meat products water lost. The presence of added sugars in meat is practically without influence. The amount of available lysine in meat can also be decreased by smoking and salting with nitrite. The values obtained for the different kinds of meat products are discussed.

Availability of Lysine in Wholewheat Bread and in Selected Breakfast Cereal

SUMMARYThe protein in wholewheat unbaked bread ingredients, microwave‐baked wholewheat bread, oven‐baked wholewheat bread, and two breakfast cereals was evaluated by gain in body weight of rats, protein efficiency ratio, increase in carcass nitrogen, and apparent availability of lysine as determined by fecal excretion.No significant differences were noted between the bread ingredients and microwave‐baked bread. Oven‐baked bread gave values significantly lower, 24–45%, than those of the ingredients. The apparent availability of lysine in bread ingredients and in microwave‐baked bread was 96% and 95%, respectively, whereas that for oven‐baked bread was 70%.The protein in one breakfast cereal barely maintained the weight of the animals, and gave low values for protein efficiency ratio and increase in carcass nitrogen. Seventy‐five percent of the lysine was available. The other cereal allowed good growth of the animals and gave values similar to those for nonfat milk. In this oat‐and‐wheat‐germ cereal, 88% of the lysine was available.A linear relation was obtained between either gain in body weight or increase in body nitrogen and the amount of available lysine ingested.

A comparison of the efficiencies of free lysine and of roller-dried skim milk, fish protein and soya bean protein for the supplementation of wheat bread.

AbstractFree L‐lysine. HCl, roller‐dried skim milk, fish protein and soya bean protein were added to the dough of wheat bread and their supplementary values for the improvement of the protein value of the bread were compared. The growth rates and nitrogen efficiency ratios of young albino rats were used as indices of the improvements obtained.Within the concentration range studied, the supplementary values of the added substances were directly proportional to the amount of available lysine which they provided. No beneficial effect from the other essential amino acids supplied by the proteins tested as supplements was detected. The data also indicate that roller‐dried skim milk suffered a considerably greater loss of lysine during the baking of wheat bread than did the other supplements.