Dye-binding stoichiometry of AO 12, AB 10B and OG with etalon proteins,feed and feedingstuffs and its application for reactive lysine determination

Our recently developed method for the determination of the reactive lysine content of soya bean proteins with the dye, Orange G, has been extended. The interactions of several etalon proteins and high protein-containing food and feedstuffs with Orange G, Acid Orange 12 and Amido Black 10B have been studied. The stoichiometric investigations showed that the reactive lysine content can be quantitatively determined by dyebinding although total nitrogen content measurements are no more advantageous than by Kjeldahl. A probable mechanism for the interaction has been given.     

Endogenous lysine flow at the distal ileum of the protein-fed rat: Investigation of the effect of protein source using radioactively labelled acetylated lysine or lysine transformed to homoarginine

The study aimed to determine if the source of purified dietary protein influenced endogenous lysine flow at the terminal ileum of the growing rat. Partially guanidinated gelatin and isolated soya bean protein based diets, containing chromic oxide as an indigestible marker, were given to 225-g liveweight rats. The endogenous flow of lysine at the terminal ileum was then determined indirectly, based on the absorption of homoarginine, after sampling of ileal contents at slaughter. Endogenous lysine flow was also determined by reference to chromium levels in sampled ileal digesta, after feeding rats either gelatin or isolated soya bean protein or casein based diets in which some of the lysine had been acetylated with [¹⁴C]-acetic anhydride. The [¹⁴C] acetylated lysine was used to distinguish between lysine of dietary and endogenous origin. Mean endogenous ileal lysine flows were 426 and 442 μ g^?1 dietary freeze dry matter intake for the guanidinated gelatin (n=6) and soya bean (n = 6) treatments, respectively, and there was no significant (P>0.05) effect of protein source on endogenous flow. Nor did there appear to be any effect of dietary protein source on endogenous ileal lysine flow when measurement was based on the radio-actively labelled acetylated lysine. The data, considered together, indicate no effect of the source of dietary protein per se on endogenous ileal lysine flow in the rat when purified proteins were given over a short (8-h) time period. The mean true ileal digestibility coefficients for dietary lysine (0.897, 0.904, 0.926, 0.971, 0.916; acetylated gelatin, guanidinated gelatin, guanidinated soya bean, acetylated soya bean, acetylated casein, respectively) indicated a high degree of absorption of lysine before the end of the ileum in the growing rat.     

The availabilities of lysine,methionine and tryptophan in Pruteen by chick growth assay

The concentrations of available lysine, methionine and tryptophan in the single-cell protein, Pruteen^a (ICI), have been determined by growth assay with young chicks. Symmetrical, six-point, parallel-line assays were used with weight gain and gain: food ratio as responses. All diets were balanced as far as possible, especially with respect to essential amino acid composition. Concurrently with the determination of each amino acid in Pruteen, its contents in typical fish and soya bean meals were determined. The assays were acceptable by the statistical criteria used. They yielded estimates of potencies that were realistic in relation to the total contents of lysine, methionine and tryptophan in Pruteen, fish and soya bean meals. The variances of potency estimates were typical of such assays. The values obtained for Pruteen considering both weight gain and gain:food ratio as responses, were about 40 g lysine, 18 g methionine and 8.7 g tryptophan kg^?1 air-dry matter. For lysine and methionine these represent high availabilities of total amino acids. The availability of tryptophan is less clear because of uncertainty about the total content of tryptophan in Pruteen.     

豆渣蛋白质的提取

本文在测定豆渣化学组成及豆渣蛋白等电点的基础上，采用简单工艺提取豆渣蛋白，粗蛋白得主继９０％以上，蛋白中必需氨基酸齐全，可以替代部分动物蛋白，具有营养高，成本低，价格廉等优点。     

Investigations on the Guanidination of Lysine in Proteins

The present study was conducted to compare the efficacy of five different reaction conditions on the guanidination of lysine in casein and to establish optimum lysine: O -methylisourea (OMIU) for maximum guanidination of lysine in casein and soya bean meal. The results indicate that the presence of glycine–NaOH buffer is not required for guanidination of proteins at pH 10·5. A OMIU concentration of 0·4 M was found to be as effective as 0·6 M for guanidination. Both OMIU–hydrogen sulphate and free OMIU were equally effective reagents in terms of conversion of lysine to homoarginine. The use of OMIU–hydrogen sulphate for guanidination and the use of ethanol to recover guanidinated protein, however, resulted in the formation of crystalline sodium sulphate, a known purgative agent, in the guanidinated material, and therefore are not recommended if the guanidinated protein is to be used in animal trials. The molar ratio of lysine: OMIU required for efficient lysine conversion to homoarginine varied for different protein sources. Ratios required for maximum conversion for casein and soya bean meal were determined to be 1:10 and 1:16, respectively. A simple procedure developed for the large-scale guanidination (5–10 kg batches) of proteins is also described. The results showed that guanidination of proteins can be easily scaled up from 20 g to 5–10 kg and that large-scale guanidination is feasible and efficient.     

Amino acid composition and biological value of pastries with protein-rich additives

The authors studied amino acid composition of confectionery (bisquits) enriched with dry fat-free milk, dried buttermilk, dry whey and soya bean flour. The biological value of the products was estimated by the sum of essential amino acids, by the ratio of essential amino acids and total nitrogen, by the chemical score and the variation coefficient of the amino acid score. It has been established that confectionery enriched with dry fat-free milk and dried buttermilk contain more lysine than those enriched with soya bean flour. The balance of amino acids is improved in the products enriched with dry fat-free milk and dried buttermilk. To improve the amino acid balance and increase protein content in food products it iz recommended that by-products of milk manufacturing be mildly used.     

Effect of Germination on Chemical Composition,Biochemical Constituents and Antinutritional Factors of Soya Bean (Glycine max) Seeds

The published scientific data concerning the effects of germination on chemical composition, biochemical constituents and anti-nutritional factors of soya bean are reviewed. The amino acid profile did not change to a great extent; only a noticeable increase in aspartic acid was observed whereas there was a gradual decrease in the available lysine level and lipid content as germination progressed. Both the total protein content and the nonprotein nitrogen increased after 5 days of germination. Dietary fibres are partially degraded in germinated seeds. Germinated soya bean is an excellent source of ascorbic acid and riboflavin. Niacin contents increased distinctly after germination. Germination induced a reduction in lipase inhibitor activity. The galactosyl oligosaccharides drastically decreased in germinated seeds. After 4 days of germination, the activity of certain lectins decreased to 4% of that of ungerminated soya beans. The phytic acid in the seeds was degraded by the phytase activated during germination, thus increasing the availability of the minerals present in the germinated seeds. Germination can degrade both Kunitz soya bean trypsin inhibitor and the major Bowman–Birk soya bean trypsin inhibitor; the degradation is enhanced, if germination process lasts more than 4 days. © 1997 SCI.     

A comparison of the interfacial behaviour of three food proteins adsorbed at air—water and oil—water interfaces

The adsorption behaviour of three food proteins—a soya protein isolate, a sodium caseinate and a whey protein concentrate—at a soya bean oil-water interface has been studied by the drop volume method. The interfacial behaviour has been compared with that at an air—water interface. The kinetics of surface tension decay were evaluated in terms of different rate-determining steps at different ionic strengths and concentrations of the proteins. The ranking order with respect to the surface activity of the proteins adsorbed at an air—water interface was the same as that at a soya bean oil—water interface. In the high concentration range the surface activity of the proteins was higher at an air-water interface than at a soya bean oil-water interface, whereas thereverse was found in the low concentration range. In general, the adsorption of the proteins was more diffusion controlled at an air-water interface than at a soya bean oil-water interface; this suggested that proteins were less folded at the soya bean oil-water interface. A comparison of the rates of the diffusion controlled steps for the proteins at air-water and soya bean oil-water interfaces indicated that the solvation energy gained when caseinates adsorb at the soya bean oil interface was enhanced compared with the other two proteins. This indicated an enhanced loop formation of the caseinate molecules in the oil phase when adsorbing at this interface, as compared with the air-water interface.     

Saponin content of soya beans and some commercial soya bean products

Quantitative thin layer chromatography has been used to estimate the saponin content of whole soya beans (Glycine max L. Merrill, cv. Williams) and a number of commercial soya bean products such as protein isolates and lecithin. Saponins were present in all these materials at concentrations ranging from 56 g kg-¹ (on a dry weight basis) for whole soya beans to 3 g kg-¹ for the protein isolate ?Promine-D’?. Previous estimates indicate a saponin content of whole soya beans of only about 5 g kg-¹. It is suggested that this is an underestimate resulting from loss of material during the extraction procedures used in earlier methods of analysis.     

Effects of heat treatment on lysine in soya protein

Total lysine and available lysine were used For predicting the damage to lysine in soya protein heated with glucose and in alkali. The amounts of both types of lysine decreased during the treatments. The content of total lysine was much higher than that of available lysine. In soya protein heated with glucose, the available lysine content decreased by 78-85 % and that of total lysine by 17-40 %. In soya protein heated in alkali, available lysine decreased by 7-24% and total lysine by 7-13%. Since available lysine was more sensitive, changes in total lysine underestimated the nutritional damage.     

A collaborative study on the determination of available lysine in feeding stuffs

The methods of Carpenter¹ and Roach, Sanderson and Williams² for the determination of available lysine have been compared in two collaborative studies involving eight laboratories. The feeding stuffs used were: fish meal and groundnut meal in Trial 1 and soya bean meal, sunflower meal, a commercial mixed feed and wheat meal in Trial 2. There was no statistically significant difference between the two methods in terms of their overall means for any of the materials studied, though for mixed feed the values by Carpenter's method tended to be smaller. Inter-laboratory standard deviations for available lysine were generally greater by Carpenter's method, but significance was established only in the case of wheat. - Some of the problems encountered in both methods are discussed.     

不同功率超声波对提高大豆浆蛋白质含量的影响

针对传统大豆磨浆出浆率低的问题 ,应用超声波特有的物理性质来提高大豆蛋白质和固形物回收率。使用频率 2 8kHz ,输出功率为 2 0 0、40 0或 60 0W的超声波在大豆磨浆前后对样品进行一定时间的处理 ,通过跟踪豆浆中蛋白质和固形物的变化来检测超声波的作用效果。结果表明 ,在大豆磨浆前后利用超声波处理 2次 ,其豆浆中蛋白质含量比空白的提高了 68 98% ,可溶性固形物的含量也比空白的提高了 67 94%。超声波处理可以显著提高大豆浆的蛋白质和可溶性固形物的含量     

The nutritional quality of two types of fish silage for broiler chickens

Fish waste was ensiled either by acidification with formic acid or by fermentation with a bacterial starter culture and molasses. The resulting liquids were mixed with wheat bran (85:15 w/w liquid: bran) and dried (70°C) to produce acid silage meal (ASM) and fermented silage meal (FSM). ASM and FSM were incorporated into wheat-based diets at 25, 50 and 100 g kg^?1 at the expense of soya bean meal. There were two control diets, one which contained soya bean meal as the predominant protein supplement and a second in which fish meal (50 g kg^?1) was added at the expense of some of the soya bean meal. Starter diets (13.25 MJ ME kg^?1, 12 g kg^?1 lysine) were fed from 1-day-old to 21-days-old and finisher diets (13.25 MJ ME kg^?1, 9.5 g kg^?1 lysine) were fed from 22 to 42-days-old to six replicates each of five birds. Birds were reared in raised-wire cages, and feed intake, liveweight and mortality were recorded. There were no significant effects of dietary inclusion of either ASM and FSM on the performance of broiler chickens relative to those fed on control diets. FSM contained less crude protein and amino acids than ASM. The recovery of amino acids relative to the total crude protein content from FSM was only 78.7%, presumably as a result of formation of Maillard reaction products during drying.     

Nutritional assessment of defatted oil meals of melon (Colocynthis citrullus L.) and fluted pumpkin (Telfaria occidentalis hook) by chick assay

Analytical data on fatty acid, amino acid and mineral content of defatted melon seed and fluted pumpkin seed are presented and discussed. Also discussed are experimental data on availability of amino acids and minerals in these meals. Defatted melon seed and fluted pumpkin seed have protein contents of 66.20% and 66.54%, respectively, with an excellent pattern of amino acids, containing higher levels of most essential amino acids (except lysine) than soya bean meal. Amino acid availability is high (melon seed 95.30%, pumpkin seed 93.12%) and similar to the level in soya bean meal (94.31%). Mineral availability is significantly lower in melon seed (53.63%) and soya bean meal (54.94%) than in pumpkin seed (58.84%). The potential for increased dietary utilisation of melon and fluted pumpkin meals and flours to meet the dietary needs of monogastric animals as well as human subjects is discussed.     

Effects of alkali treatment on the in-vitro digestibility of proteins and the release of amino acids

Three protein sources, casein, soya bean and rapeseed concentrates, were subjected to alkali treatment (0.2 M, 60° C) for 2 or 6 h. The impact of these treatments on protein digestibility and on release of amino acids, especially lysinoalanine, was evaluated by an in-vitro enzymic digestion method with simultaneous dialysis of digestion products. The impairment of digestibility was higher for casein and soya bean concentrate than for rapeseed concentrate. Whatever the amount of lysinoalanine produced in each protein, it was poorly released by proteolytic enzymes. The rate of release of other amino acids was reduced by the treatments, but to different levels for each protein. Arginine and lysine were particularly affected. As can be inferred from the release of the target amino acids, the hydrolytic capacity of chymotrypsin was not specifically impaired, in contrast to that of trypsin for casein and of elastase for all protein sources. This technique was useful to evaluate quickly the effects of processing on the digestibility of proteins.     

Accumulation and quality of storage protein in developing cowpea,mung bean and soya bean seeds

This study was carried out to compare the time course of laying down seed storage protein in three legumes viz: cowpea (Vigna unquiculata), mung bean (Phaseolus aureus) and soya bean (Glycine max) planted in two replications. Pods were harvested periodically during seed maturation and studied for changes in fresh and dry weights, total sulphur, total nitrogen and protein content. At early stages of development crude protein formed about one-third of dry weight in the legumes but decreased to about one-quarter at maturity. The total sulphur which formed a substantial amount of the sulphur amino-acids in mature seeds did not change much in mung bean and cowpea but increased by about 24% from 20 to 69 days after flowering (DAF) in soya bean. Storage protein accumulation was very rapid between 10 and 14 DAF (10.4% day^?1) in mung bean, 7 and 14 DAF (12.9% day^?1) in cowpea and between 20 and 30 DAF (9.4 day^?1) in soya bean. Thereafter, protein accumulation declined slightly and gradually approached zero at time of seed maturity. The sulphur-to-nitrogen ratios gradually increased with maximum values in the mature seeds. Although seed protein content and quality (on S/N ratio basis) were highest in soya bean, accumulation of storage protein seemed to be faster in cowpea than mung bean and soya bean during seed maturation.     

Determination of β-sitosterol in meats,soya and other protein products

β-Sitosterol is shown to be present in a range of soya bean products, egg powder, several meats and wheatflour. Sterols were isolated and β-sitosterol in the resultant mixture was determined by GLC. Repeated analyses of individual samples displayed wide variance and the soya bean products themselves exhibited considerable interproduct variation in β-sitosterol content. A level of β-sitosterol similar to that found in soya products was found in wheatflour and somewhat lower levels in beef, pork, lamb and egg powder. The method cannot be used for the quantitative determination of soya in meat products but may be of some diagnostic value.     

Feeding differently processed soya bean. Part 2. An assessment of haematological responses in the chicken.

The use of differently processed soya bean as a major source of dietary protein was evaluated in a haematological study using broiler chickens in which groundnut cake (GNC), raw soya bean (RSB), roasted soya bean (RtSB), cooked soya bean (CSB) and soya bean oil cake (SBC) were fed on equi-protein basis. The results showed that: 1. Red blood cell (RBC) count and haemoglobin content of blood significantly (P less than 0.05) increased in chicks fed RSB relative to the other soya bean diets. Feeding differently processed soya bean significantly (P less than 0.05) influenced mean cell haemoglobin (MCH) and mean corpuscular volume (MCV) while the mean corpuscular haemoglobin concentration (MCHC) was not significantly influenced. 2. Both the total white blood cell (WBC) count and the monocytes were significantly (P less than 0.05) influenced by the dietary treatments. Chicks fed processed soya bean generally had higher number of monocytes. 3. Physical properties determined were specific gravity and erythrocyte sedimentation rate. The latter was significantly (P less than 0.05) lower in all the processed soya bean-fed chicks. 4. Minerals determined in blood were Na, K, Ca, Mg, Fe, Cu and P. Of all these, chicks fed RSB had significantly (P less than 0.01) lower levels of blood Mg and marked decrease in Ca.     

Composition of marama bean protein

The protein composition of marama beans, an indigenous African oilseed legume, was determined in comparison with soya beans. Marama bean protein contained a substantial amount of tyrosine compared with soya bean protein. It was slightly richer in proline than was soya. By SDS–PAGE, marama protein contained fewer protein bands than did soya. The patterns of these bands in marama under non-reducing and reducing conditions were similar, suggesting an absence of disulphide bonds. The vicilin (7S) and acidic 11S subunits seemed to be absent in marama. This is most unusual in legume proteins. Only a major basic legumin (11S) (20 kDa), medium (63 kDa) and high (148 kDa) molecular weight protein bands were separated for marama. Most polypeptides in the marama proteome map are basic compared with soya. Only one polypeptide match, comparable to soya, was tentatively identified. Marama protein composition is very different from that of soya.     

On the Adequacy of Methods for the Quantitative Determination of Reactive Lysine in the Free Form or in Small Peptides

Reactive lysine determination in mixtures containing lysine in the free form or in small peptides by the l-fluoro-2,4-dinitrobenzene (FDNB) procedure is complicated by the fact that both amino groups of lysine can react with FDNB. Quantitative conversion of lysine to its copper salt, followed by reaction with FDNB, has been reported. However, the present study demonstrated that copper complexation was incomplete, even when alanine was added to better protect the free α-amino group of lysine. The FDNB procedure would, therefore, be of questionable value for the determination of reactive lysine in protein hydrolysates.