The nutritive value of porcine blood plasma concentrates prepared by ultrafiltration and spray Drying

Concentrated solutions of porcine blood plasma proteins, prepared by centrifugation and ultrafiltration⁴ were spray dried directly at air inlet temperatures of 154, 170.3, 225 and 243.2 °C. Spray dried concentrates contained ca 86–90% protein, ca 2–7% moisture and ca 5% minerals. The overall amino acid composition of the plasma proteins compared favourably with that of FAO whole egg protein.¹² Although the values of essential amino acids generally fell below the egg values, the only serious limitations were in the content of isoleucine (less than half of the egg value). The chemical score (CS) and essential amino acid index (EAAI) were 49.1 and 70.1 respectively. Rats fed on a diet containing plasma concentrate as the sole protein source showed a net weight increase. NPU carcass for plasma protein was 65.8 ± 1.9 compared with a value of 72.1 ± 0.4 for a casein control. An inverse correlation between denaturation status of plasma proteins and spray drying temperature was found. The percent denaturation as measured on pH 4.0 filtrates increased from 8.4% at an air inlet temperature of 154 °C to 48.6% at a temperature of 243.2 °C. A similar inverse relationship was found between the available lysine content of plasma proteins and spray drying temperature. A maximum decrease in percent lysine availability of 16% was found at an air inlet drying temperature of 243.4 °C.     

Improvement of the nutritive value of cereals by leaf protein supplementation

The gross composition and amino acid content of the proteins of barley, corn, rye and wheat grains were determined. Leaf protein concentrates (LPC) were produced from the green matter of clover, lucerne, barley and ryegrass using standard methods and analysed as for the cereal grains. Each cereal was mixed with each concentrate at a protein ratio of 2:1, respectively. The chemical score (CS) and essential amino acid index (EAAI) of the cereals, the protein concentrates and their mixtures were calculated. The biological value (BV) and true digestibility (TD) of all proteins were determined on rats using the Thomas-Mitchell balance method. LPC proteins contained more lysine (4.6–6.0%) but less cystine than cereal proteins (2.8–3.8 and 2.3–2.7 g per 16 g N, respectively). The CS and BV of LPC proteins were low (30–40 and 44–58, respectively) because of the low cystine content. Mixing cereals with LPC improved the CS, EAAI and BV of their proteins. The BV of the protein mixtures was in almost every case higher than that of either protein alone, but the digestibility of the cereal proteins was reduced as a result of admixture with LPC, especially with clover LPC.     

Influence of thermoplastic extrusion on the nutritive value of bovine rumen protein

This study investigated the impact of thermoplastic extrusion on the nutritive quality of bovine rumen protein. Proximal composition, amino acid profile and in vivo true protein digestibility among rats were determined in raw (RBR) and extruded (EBR) rumen. Raw and extruded bovine rumen presented high percentages of protein (more than 95% on dry basis). Neither raw nor extruded proteins had any limiting amino acid, and the RBR and EBR amino acid scores were, respectively, 1.28 (leucine) and 1.25 (methionine plus cystine). Extrusion reduced significantly true protein digestibility from 97.7% to 93.1% (p < 0.001), but protein digestibility-corrected amino acid scores for both proteins (RBR and EBR) were 100%. Animal growth presented comparable profiles using raw and extruded rumen. In conclusion, thermoplastic extrusion did not affect the protein quality of bovine rumen, and this does not hinder the use of this material as a food ingredient.     

Effect of thermal processing on the nutritive value of wheat germ protein

Wheat germs are used as industrial products for nourishment so that it was necessary to determine the nutritive value of proteins in raw and in roasted wheat germs (temperature: 130–150 °C for 20 min). Protein quality evaluation has been determined by a biological method - feeding young growing rats. The rats were fed 10% level protein diets, based on raw and roasted wheat germs. The results show that protein of roasted wheat germs has higher digestibility (D) and protein efficiency ratio (PER) than the raw wheat germs which proves that roasting destroyed digestion enzymes inhibitors. Furthermore, the net protein utilization (NPU) has also been improved by roasting. Biological value (BV) of raw germs approximates to the value of roasted germs. The results lead us to the conclusion that roasting saves and improves protein parameters in wheat germs.     

Evaluation of protein concentrates prepared from rapeseed meal

Protein concentrates have been prepared from rapeseed meals by extraction with sodium chloride solution, followed by removal of the seed coat by screen filtration. This method yielded up to 75% of the original meal N in the form of products containing 61–64% protein (Nx 6·25). The products showed a considerably greater content of ash, and lower content of crude fibre and glucosinolate than did the starting meals, but amino acid patterns were similar and P levels were unchanged. Protein quality of the products prepared from heat-treated (myrosinase-inactivated) meals, was measured by determination of protein efficiency ratio and net protein utilisation, and was found to be similar to that of casein.     

Mineral composition of the protein concentrates made from nontraditional raw plant materials

Protein concentrates obtained from unconventional plant raw material, namely from the oil cake of tomato seeds, corn germs, flax and safflower hold promise as sources of biologically important components including mineral substances. The protein concentrates are marked by a high content of calcium, magnesium, phosphorus, copper, manganese and zinc. They are also rich in iron that occurs in the form of a protein complex of bivalent iron. The content of heavy metals and nitrates does not exceed quota permissible for foods.     

Optimalization of the protein content of canned baby-foods based on their nutritive value

When planning canned foods the protein value Net Dietary-protein Energy percent = 8% of a 5-month old infant's requirement was considered as constant. The nutritive value required for this purpose was calculated on the basis of amino acid composition, making use of the MORUP-OLESEN index. Canned foods were made of two protein-containing components, of sunflower-oil and (occasionally) of starch, by computer, keeping the energy value constant, i. e. 1250 kJ, which covers half of the infant's daily requirement. The optimalization based on the protein value is illustrated by the examples of egg-potato, beef peas and flour-beans pairs, considering the practical requirements as well.     

Effect of mild autoclaving and deamidisation on the nutritive value of protein fractions

The nutritive value of zein, rapeseed 12S and α-casein was assessed by apparent digestibility coefficient (ADC) and net protein ratio (NPR). Protein fractions were suspended (100 g litre^?1) in 0.1M HCl or in water and autoclaved for 1 h. The degree of deamidisation following acid autoclaving was 14.0% for zein, 7.3% for rapeseed 12S and 8.9% for α-casein. Results indicate that autoclaving in water or in HCl improved the ADC of zein and rapeseed 12S. However, acid autoclaving increased (P<0.05) the NPR of rapeseed 12S (from 3.07 to 3.44) whereas it decreased (P<0.05) that of α-casein (from 4.21 to 3.57).     

Higher protein content from nitrogen fertiliser application and nutritive value of milled-rice protein.

An increase in milled-rice protein content (N x 6.25) from 8.14 to 9.90% (at 12% moisture) in IR8 and from 9.90 to 13.0% in IR480–5–9 due to N fertiliser application had no significant effect on the lysine content of the protein and had little effect on the true digestibility, the biological value, and the net protein utilisation of the protein in growing rats.     

The nutritive value of mixtures of white leaf protein and food proteins

White leaf protein products were obtained from Medicago sativa by precipitation with isopropanol and from Chenopodium quinoa by heat fractionation and ultrafiltration/diafiltration. The isopropanol precipitated protein concentrate from Medicago contained less protein and more ash than the heat fractionated preparation from Chenopodium. The biological value of the protein fraction obtained from Medicago, estimated on rats using the Thomas-Mitchell balance method, was 59. The biological value of the protein preparation from Chenopodium was low (36). The preparations obtained were mixed with soya bean meal, wheat gluten, bone-meat meal, fish meal, skim milk and whey in a protein ratio 1:1. In every case, except fish meal, the biological value of the mixtures was higher than that of each component separately. This improvement of the nutritive value can not be explained from the amino acid composition; possibly the lysine availability was low. White leaf protein can, with advantage, supplement other food proteins.     

Effect of contamination of foods by Aspergillus flavus on the nutritive value of protein

The effect of aflatoxin was measured on the protein quality of peanut meal (PNM) and fish meal (FM) Total protein efficiency, protein efficiency ratio, net protein utilisation, examination of the histopathology of the liver, ileal digesion of amino acids and plasma amino acid concentration were used as bioassays together with chemical score (CS), dye binding capacity (DBC), essential amino acid index (EAAI), and discriminant computered PER (DC-PER) as chemical methods. In trial 1, aflatoxin-free PNM was compared with infected PNM at graded levels of toxin when fed to chickens and ducklings. In trial 2, various mixtures of PNM and FM at a constant aflatoxin level (280 μg kg^?1) were fed to compare the effects of aflatoxin on proteins of differing quality. Ducks were more sensitive to the toxin than chickens, as indicated by deterioration of protein quality, and the effects on growth and the histological appearance of the liver were magnified on diets of low quality (PNM), but not of high quality (FM). Contamination of PNM resulted in progressive increase in DBC and, to a lesser extent, in DC-PER, while EAAI and CS were not affected. The importance of these findings lies in the problems of mould contamination of animal feedstuffs in humid, tropical conditions, which may affect the more sensitive animals, and may not be detected by chemical methods of measuring protein quality, nor by bioassay on chickens, if the levels of contamination are low.     

Chemical composition and nutritive value of leaf protein concentrate from leucaena leucocephala

Leaf protein concentrate (LPC) was prepared from Leucaena leucocephala leaf meal (LLM). The recovery of LPC was 7.6 % and analysis showed that the LPC contained 65.91 % crude protein compared with 29.15 % of the LLM, ash content was 17.56% while levels of essential amino acids-lysine, histidine, arginine, isoleucine and leucine—were 5.57, 2.34, 5.88, 5.42 and 10.8% on a dry matter basis, respectively. The LPC had higher in-vivo digestibility than the LLM with values being 63.20 and 48.82%, respectively. The LPC diet supported growth in rats but gave lower nutritive indices than the control diet of soya bean and Guinea corn.     

The nutritive value of protein isolates and fibres from meat industry by-products

Protein isolates extracted from rumen, lung and plasma by alkaline solubilisation were spun into protein fibres and were evaluated for protein quality by rat feeding trials and by amino acid analyses. The net protein utilisation (NPU) of the fibres ranged from 53·0 to 76·9 for plasma and rumen fibres respectively, methionine plus cystine and valine being limiting amino acids. Lysine was not found to be a limiting amino acid in any sample and lysine availability was high in isolates and fell only slightly on spinning. There was a marked discrepancy between chemical score and NPU for rumen isolate and it is postulated that an anti-nutritional factor, possibly a trypsin inhibitor, normally present in bovine organs, could be active in the isolate by lowering methionine availability to the animal and decreasing NPU. Spinning the proteins, however, either destroys the inhibitor or decreases its concentration since NPU and chemical score become equal.     

Study of nutritive value of modified casein

It has been shown that modified casein purified from carbohydrate components contains several times less phosphorus and calcium as compared to initial casein. Figures close to experimental and potential biological value were obtained in experiments on growing rats with modified and initial casein as a protein component-milk substitute.     

Effect of fermentation on the nutritive value of maize

The effects of fermentation on protein, in vitro protein digestibility (IVPD), amino acid, total phenolics, phytic acid and colour values of four maize cultivars (two bi‐colour waxy corn and two super sweet corn), namely Jing Tian Zi Hua Nuo NO. 2, Jing Tian NO. 3, Bright Jean and Su Ke Hua Nuo 2008, were determined and compared with those of their unfermented counterparts. Results showed that fermentation caused significant increase in protein (43.5% largest increase), most kind of amino acid (131.5% largest increase in lysine content) and total phenolic content (23.4% largest increase), but significant reduction in phytic acid content (24.3% largest reduction) of four maize cultivars. The IVPD of four maize cultivars, except Suke2008, did not change significantly. Colour values of two waxy corn were resulted in the increase in a‐values and reduction in L‐values.     

Some studies of the nutritive value of high-lysine barleys

In five separate experiments, three high-lysine (HL) barley lines were compared with the HL mutant Risø 1508 and the normal variety Maris Mink (MM), for their lysine content, protein quality and metabolisable energy (ME). The HL barley lines were selected from crosses between Risø 1508 and Julia or Lofa Abed. Lysine content (g/16 g N) as measured by four different procedures was found to be from 11 to 28% higher in the HL barleys compared to MM. True nitrogen and lysine digestibility were only slightly reduced (6 and 4%, respectively) in the HL barleys when they were fed as the sole N source in purified diets for rats in an N-balance trial. A subsequent 17% improvement in protein retention efficiency (PRE) was noted in the rat trials when the HL barleys provided the N source rather than MM. Further supplementation with lysine did not improve PRE values for the HL barleys though a significant response was noted with MM samples. Although the gross energy content of all the barleys was similar, the ME values of the HL barleys were some 8-15% lower than the corresponding values for MM. The reasons for this and the potential economic value of these HL barleys are discussed.     

The nutritive value of some pakistani diets

The nutritive values of Pakistani diets and meals commonly consumed by rural peasants and middle-class city dwellers was determined chemically (including fatty acid and amino acid analyses) and biologically in N-balance experiments with growing rats. The average national diet supplies 13% of the total calories from protein, 61% from carbohydrate and 11 % from fat. Essential fatty acids, iron and calcium content are adequate to meet the dietary requirements. Lysine and threonine were found to be the limiting amino acids in the average national diet, the northern area diet and most of the meals. The national diet has a slightly higher net protein utilisation (NPU) value (66%) than that of the northern area (61 %). Net dietary protein calories percentage (NDp cal %) was highest (8.5) for the national diet. The NDp cal % of the wheat bread and rice based meals lie between 5.9-8.3 and 5.4-6.4 respectively. The results suggest that protein is not a limiting factor in Pakistani diets when compared with FAO recommendations.     

浅析黄酒的历史及营养价值

从黄酒的悠久历史及营养价值两个方面论述了我国黄酒的发展，并着重分析了黄酒的成分及营养功效之所在，为黄酒的发展和消费提供了可靠的依据。