Fatty acids,mineral composition ond functional (bread and chapati) properties of high protein and high lysine barley lines

Six barley lines derived from corsses involving Hiproly (SV 73608×Mona⁵) and Riso 1508 with higher yield recipients V 43-42 and V 5681, along with the four parents, were analyzed for faty acids and mineral composition. Dough properties, bread and chapaties were charcterized by blending barley line (B82503) at 2.5-25% with bread wheat flour (pak 81). Fatty acid contents were myristic acid, 0.60-1.16%; palmitic acid, 16.68-20.84%; stearic acid, 1.30-3.33% and degree of unsaturation 1.40-1.50%. The derived lines contained similar amounts of essential fatty acids. Significant variation for magnesium, copper, zinc, phosphorus and potassium was observed but overlapped among the lines and parents. The calciu, iron, and manganese showed non-significant differences among lines and parents. Blending up to 10% barley flour with bread wheat flour gave farinograph characteristics comparable to those of pure wheat flour, but increasing the proportion of barley beyond this decreased the mix time and dough stability. Breadbaking tests verfied that up to 10% barley could be mixed with wheat without adversely affecting loaf volume and other quality attributes. For chapati making up to 20% barley could be blended into the wheat, yet yield acceptable quality.     

AMYLASE ACTIVITY AND ENDOSPERM HARDNESS OF HIGH LYSINE BARLEYS

Several of the high lysine barleys selected by the Udy dye binding method have altered proportions of the main protein fractions. These varieties also vary considerably in endosperm hardness measured as the amount of electrical energy required for milling. A few have endosperms requiring a higher milling energy than that of the parental variety, but five high lysine varieties have soft endosperms typical of barleys that malt readily. In addition the high lysine selections differ markedly in β-amylase and diastatic activity. Mutant R 1508 with the highest grain lysine has very low diastatic activity, whereas R 56 and Hiproly have diastatic activities equivalent to that of a known high diastase barley. α-Amylase activity of high lysine barleys also ranges widely and tends to be inversely related to diastatic activity.     

The effect of varying nitrogen supply on the protein composition of a high lysine mutant of barley.

Amino acid analyses of the grain of barley cultivars Risø 1508, Hiproly and Maris Mink carried out using grain of comparable protein levels have shown that the amino acid composition of Risø mutant 1508 is fundamentally different from that of the other varieties. A high proportional content of lysine and other nutritionally essential amino acids in Risø 1508 is achieved mainly at the expense of large decreases in glutamic acid and proline. Furthermore, a high lysine content in Risø mutant 1508 was maintained when the level of grain protein was raised by increasing the supply of nitrogen fertiliser.     

The effect of irrigation and nitrogen supply on the yield and quality of protein in high-lysine barleys

The high-lysine barley mutant 1508, a selection derived from it and its parent variety Bomi, were grown in a trial with two other varieties of normal-lysine content, Maris Mink and a dwarf selection, HG 31 DD. Irrigation was applied as a main treatment and nitrogen as nitrochalk was applied either as a top dressing alone or with the subsequent addition of urea as a foliar spray at anthesis. Both high-lysine barleys and Bomi showed a greater yield response to irrigation than the other varieties but did not differ in their response to nitrogen. On average, the high-lysine barleys yielded as well as the normal varieties Bomi and Maris Mink but had a higher content of protein in the grain and of lysine in the protein, resulting in substantially higher yields of protein and lysine per hectare.     

Nutritional evaluation of high protein genotypes of barley

High protein strain B_I and high lysine mutant Notch-2 of barley were evaluated for their nutritional quality and compared with standard varieties. B_I with bold and plump grains was found to possess higher inherent protein synthesising capacity without affecting starch synthesis. Higher protein percentage in Notch-2 was due to reduced grain weight. It is suggested that protein per grain and protein yield per unit area should be taken as indices in breeding for improvement in protein quality. Chemical as well as biological tests showed that B_I and Notch-2 are the genotypes with better protein quality as compared to NP 113 and Jyoti. Higher lysine content in Notch-2 was mainly due to the higher proportion of albumin and decrease in prolamin fraction. Digestible energy, however, was low in Notch-2.     

A new candidate protein for high lysine content in wheat grain

Lysine is the most limiting essential amino acid in cereal grains, so that grain lysine content is important for human nutrition and livestock growth. Translation elongation factor 1α (EF‐1α) from cereal embryo was recently reported to be rich in lysine, and the possibility of using this protein as a marker for feed quality was explored in maize. In this study we used immunochemical methods to investigate the relationship between the content of EF‐1α and other proteins from wheat germ and lysine content in both hexaploid (bread) wheats and diploid wheat progenitors to the wheat A‐genome. The levels of grain lysine, as well as their variation between lines or cultivars, were greater for the diploid wheats. While there was a significant correlation between the levels of EF‐1α and grain lysine content, the binding of antibodies to a protein of M_r 37 000 showed a higher correlation. This protein was characterised by amino acid sequencing as fructose 1,6‐bisphosphate aldolase. The possibility of using fructose 1,6‐bisphosphate aldolase as a marker for feed quality and development of a simple ELISA for quantification of lysine in wheat is demonstrated. © 2000 Society of Chemical Industry     

Nutritional evaluation of high protein genotypes of pearl millet (Pennisetum americanum (L.) leeke)

Three high protein (HP) inbred lines (700112, WC-190 and B-816) of pearl millet were studied for their nutritional quality and the results compared with those of normal protein varieties. The protein content of HP lines showed an average increase of 60% but the starch and soluble sugars together and the fat content decreased by 40 and 20%, respectively. Total dietary fibre of the HP lines was about 10% higher. A decrease (about 20%) in the albumin fraction was associated with an increase in prolamin in HP lines. The amino acid composition of the HP lines remained normal except for an approximately 16% decrease in lysine. However, the total amount of lysine in the sample increased by an average of 37%, as a result of a substantial increase in protein content. True protein digestibility was very high for each line but, expectedly, the biological value was markedly lower. The values for utilisable protein were highest for high protein genotypes. Digestible energy was high in all the genotypes, although slightly lower values were obtained for the HP lines; this was attributed to the fibre fractions.     

Fractionation and amino acid analysis of the salt-soluble protein fractions of normal and high-lysine barleys

High-lysine barleys derive their high lysine content, in part, from an increase in the salt-soluble proteins. These proteins were extracted in 0.5m sodium chloride from milled grain of the genotypes Hiproly, Risø 1508, Risø 7, Bomi, Vada and Ark Royal. The extracts were subsequently separated into albumins and globulins by dialysis against distilled water, and were examined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and amino acid analysis. SDS-PAGE revealed that the polypeptides of both fractions were highly heterogeneous with respect to molecular weight. There were marked differences in the polypeptide composition of the albumin fraction of the high-lysine genotypes compared to the normals, but relatively smaller differences in the globulins which were generally higher in lysine and lower in glutamic acid than the albumins. The albumin fraction of Hiproly had a very high level of lysine compared to the other genotypes and surprisingly the globulin fraction of Risø 1508 had a low lysine content. The consequences of these findings are discussed in relation to strategies for breeding high-lysine barleys.     

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.     

The effect of nitrogen nutrition on the lysine content and protein composition of barley seeds

Increases in the total grain nitrogen of barley (cv. Julia and Bomi), resulting from increased N fertilisation, are accompanied by decreases in the relative lysine content of the grain proteins. Extraction of the grain proteins shows that the high-N grain have increased relative and total amounts of the lysine-poor storage protein (hordein) fraction. There are only small increases in the total amounts of the other more lysine-rich protein fractions (salt-soluble proteins and glutelin+residue proteins). There is also little or no effect on the amino acid compositions of the fractions. Consequently, it is concluded that the decreased relative lysine content of the whole grain is due to the increased synthesis of hordein. Further evidence for this hypothesis comes from similar studies with the high-lysine mutant, Risø 1508, in which the high-lysine character results from a decrease in the relative and total amount of hordein. The hordein fraction does not increase disproportionately with increasing grain N, nor does the relative lysine content of the grain decrease. There is no effect of grain N on the polypeptide compositions of the salt-soluble proteins of either line. However, in Bomi and Julia increased grain N does result in an increase in the relative amount of sulphur-poor ‘C’ hordein polypeptides in the hordein fraction. It is speculated that this results from limitation of S relative to N.     

Blocked Lysine in Dairy Products: Formation,Occurrence, Analysis,and Nutritional Implications

Lysine residues in milk proteins become “blocked” when they react with reducing sugars, particularly lactose, in the Maillard reaction. The blocked or glycated lysines reduce the biological availability of the lysine to metabolic processes and also hinder hydrolysis of the parent protein by digestive enzymes. Heating and storage of milk and milk products are the major promotants of the Maillard reaction and resulting chemical damage to the proteins. Several methods have been proposed to estimate the extent of this protein damage. Two major compounds, furosine, a product of acid hydrolysis of lactulosyl‐lysine, the 1st stable product of the Maillard reaction, and carboxymethyl‐lysine are used for assessing the early and advanced stages of the Maillard reaction, respectively. In addition, several methods are used for assessing the bioavailability of lysine in a protein; these include chemical, enzymic, and animal‐based methods. This review discusses the Maillard reaction and its significance in milk and dairy products, methods of assessing the extent of the reaction and of the bioavailability of lysine, and the nutritional significance of blocked lysines and associated Maillard reaction products in milk proteins.     

Nutritional assessment of transgenic lysine‐rich maize compared with conventional quality protein maize

BACKGROUND: The gene sb401 encoding a lysine‐rich protein has been successfully integrated into the genome of maize (Zea mays), its expression showing as increased levels of lysine and total protein in maize seeds. As part of a nutritional assessment of transgenic maize, nutritional composition, especially unintended changes in key nutrients such as proximates, amino acids, minerals and vitamins as well as in antinutrient (phytate phosphorus), and protein nutritional quality were compared between transgenic maize (inbred line 642 and hybrid line Y642) and conventional quality protein maize (QPM) Nongda 108. RESULTS: The contents of total protein, lysine, some other amino acids, several minerals and vitamin B₂ in transgenic inbred line 642 and hybrid line Y642 were significantly higher than those in conventional QPM. Water‐soluble protein and G2‐glutelin were significantly promoted in transgenic maize Y642. CONCLUSION: Insertion of the lysine‐rich sb401 gene increased the total protein and lysine content of transgenic maize varieties, leading to an improved amino acid score and therefore an improvement in the nutritive value of maize. © 2013 Society of Chemical Industry     

Interactions between the kernel N sink, grain yield and protein nutritional quality of maize

The isogenic opaque-2 (o2) and its normal counterpart of maize (Zea mays L.) hybrid ‘B14 × B37’ were used as a model system and grown under different levels of nitrogen fertility to test the importance of the kernel N sink (zein accumulation) relative to kernel osmotic potential, dry matter accumulation, grain yield and protein nutritional quality. Self-pollination and reciprocal crosses were made with seven o2 hybrids and their normal counterparts in order to determine the effect of the kernel N sink and/or vegetative characteristics on kernel dry weight accumulation. The results indicate that with a small supply of nitrogen, both normal and o2 kernels produced only small amounts of zein, and kernel weights and grain yields were comparable. As the level of nitrogen increased, zein accumulated preferentially in normal, but not in o2, and differences in kernel weight and grain yield between these two genotypes became greater. The reduction of dry matter accumulation in o2 kernels relative to normal kernels when grown under high N levels may result from the accumulation of free amino acids and their catabolic products in the kernel as a consequence of a small N sink. These osmotica contributed to a more negative osmotic potential which may favour water movement, but reduce solute movement into the kernel. Increased zein accumulation in normal kernels enhanced kernel weight and grain yield but reduced protein nutritional quality. The concentration of lysine and tryptophan as a percentage of protein decreased as the level of N fertiliser and kernel protein in the normal kernel increased. On the other hand, the o2 mutant failed to deposit additional N as zein; therefore, the concentration of these two essential amino acids remained constant regardless of N levels. However, when lysine and tryptophan were expressed on an area (kg ha^?1) basis, the amino acid yields of these two genotypes were comparable.     

Variation in in vitro digestibility of barley protein.

In vitro digestibility of protein was measured with pepsin/pancreatin in 321 spring barley lines grown in the field. The variation in digestibility was far less than the variation in the protein content. A small environmental influence on the digestibility was found. Two entries had slightly impaired digestibilities; these findings were partially verified in a repeated field trial, but were not confirmed in vivo. In vitro digestibilities of barleys grown in pots at various N-levels were positively correlated with protein or hordein content. In vitro digestibility was negatively correlated with the fibre content in decortification fractions of Bomi and the high-lysine mutant Risø 1508. The digestibility was positively correlated with the hordein concentration for the Bomi fractions, but not for the 1508 fractions.     

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.     

Proteins of Italian millet: Amino acid composition,solubility fractionation and electrophoresis of protein fractions

Determination of the protein contents of 14 varieties of Italian millet revealed considerable varietal differences. The total protein of the 14 varieties was fractionated into albumin-globulin, prolamin and glutelin fractions. The prolamin fraction constitutes the major storage protein of the grain. There is a positive correlation between protein content and the prolamin levels of the seeds and the increase in protein content is largely due to an increase in the prolamin content. The amino acid composition of each of 14 varieties of the millet and the individual protein fractions from three varieties were determined. The limiting amino acids are lysine followed by tryptophan and the sulphur containing amino acids, methionine and cystine. The lysine content of the grain decreases with increase in protein content. The total protein has a rather high content of leucine. SDS-polyacrylamide gel electrophoresis of the protein fractions indicated similarities in the prolamin fraction and differences in the albumin-globulin and glutelin fractions of the different varieties.     

Relationship Between Quality Parameters and SKCS Hardness Index in Malting Barley

To make an efficient and laborsaving quality selection in a malting barley breeding program, the relationship between malting quality parameters and the hardness index (HI) measured by Single Kernel Characterization System (SKCS) 4100 was studied with barley genetic resources and a group of descendant lines from “Yon Rkei 1363” that possess the high lysine allele lys1 and a very high diastatic power (DP). There was a highly significant correlation between the grain HI and the malt extract both in the genetic resources (r = ?0.48^**) and in the lys1 parent‐derived lines (r = ?0.50^**). Malt HI showed a highly significant correlation with malt extract (r = ?0.70^** in genetic resources, r = ?0.57^** in the lys1 parent‐derived lines) and malt total protein (r = 0.73^**, 0.84^**, respectively). For the selection of very high DP lines from the lys1 parent‐derived group, high grain HI selection was effective as all the very high DP lines had much harder grain characteristics. Therefore SKCS was regarded as a useful tool for quality selection in malting barley breeding.     

Nutritional and antinutritional composition of vegetable and grain amaranth leaves

The foliage of 61 accessionso f amaranthus comparising both the grain and vegetable types referable to 10 species were evaluated for carotenoid, protein, nitrate, odxalate and moisture contents (fresh weight). Carotenoid varied from 90 to 200 mg kg^?1 in vegetable types and from 60 to 200 mg kg^?1 in the leaves of grain types. Variation for leaf protein was found to be 14-30, 15-43 g kg^?1; nitrate 1.8.-8.8, 4.1-9.2 g kg^?1; oxalate 5.1-19.2, 3-16.5 g kg^?1; and moisture 780-860, 750-840 g kg^?1 in vegetable and grain types, respectively. Analysis of the amino acid composition of leaf protein of some high carotenoid lines revealed a well balanced composition with high lysine (40-56 g kg^?1). variation of all the five parameters (carotenoid, protein, nitrate, oxalate and moisture) with respect tot he leaf position in vegetable type (4- and 8-week-old plants) and with respect to age (- to 4-month-old plants) in grain types was also studied.     

Nutritional and functional properties of Vicia faba protein isolates and related fractions

The goal of this research was the characterisation of Vicia faba (broadbean) protein isolates and related fractions in order to determine whether this grain legume could be used for production of high quality protein products and other fractions rich in functional components. Alkaline extraction of the defatted seed flour, followed by precipitation at the isoelectric pH, yielded a 92% protein isolate with a high oil absorption capacity. The contents of the favism-inducing glycosides, vicine and convicine, in the isolate were reduced by more than 99% as compared to the original flour, although the amino acid composition was similar to that of the flour. Some of the by-products of protein isolate production may also be of interest from a nutritional and functional point of view. Thus, the oil resulting from hexane extraction of the flour is rich in unsaturated fatty acids, and polyphenols (resulting from extraction of the defatted flour with acetone) showed a high ABTS radical-scavenging activity. In addition, the solid residue (resulting from protein solubilisation) was high in fibre and showed good water absorption. These results show good nutritional and functional properties in V. faba protein isolates and related fractions, which may favour the revalorisation of this traditional bean crop.     

A comparison of two rapid screening methods for the selection of high-lysine barleys

A ninhydrin colour test based on the higher levels of free amino acids in the grain of a high-lysine barley mutant, Risø 1508, and a turbidity test based on its lower prolamin content, were used for the selection of single grains from F1 plants of crosses, involving it. The prolamin turbidity test was preferred for analysis of single F2 grains because it was more sensitive with grain of lower nitrogen content. In addition, turbidity was not significantly correlated with seed weight or with position in the spike of Risø 1508. Both methods are rapid, simple, inexpensive and sufficiently precise to distinguish genotypes which differ significantly in their lysine contents.