Chemical and in vivo evaluation of a brown midrib mutant of Zea mays. II. Nuclear magnetic resonance spectra of digested and undigested alkali lignins and undigested dimethyformamide lignins

Nuclear magnetic resonance (n.m.r.) spectra were obtained on the alkali lignins extracted from Tr and bm₁ cornstalks, before and after digestion by sheep, and on the dimethylformamide lignins (DMFL) from undigested cornstalks. Differences due to solvent extraction, plant genotype and digestion were apparent. The bm¹ corn lignin has a higher degree of cross linking of the propane side chain of the lignin molecule than Tr corn lignin, a factor which may be significant in determining the effect of lignin on digestibility. The main effect of digestion was to increase the degree of cross-linking of the propane side chain, especially with the Tr lignin. Alkali lignin n.m.r. spectra were considerably different from DMFL n.m.r. spectra. For example over 40% of the total bm DMFL protons were highly shielded protons but these were virtually absent in the alkali lignins. These highly shielded protons cannot be explained by the presence of ferulic and p-coumaric acids in DMFL.     

Phenolic components and degradability of the cell walls of the brown midrib mutant,bm3, of Zea mays

Cell walls separated from the leaf blade, leaf sheath and stem of the brown midrib mutant, bm₃, of Zea mays were more degradable by a commercial cellulase than the corresponding part of the isogenic normal inbred cultivar (Tr). The walls of each part of the mutant when compared with the corresponding part of the normal cultivar contained less lignin and bound phenolic components released by treatment with NaOH. The major phenolic components detected were trans-p-coumaric and trans-ferulic acids together with small amounts of their cis isomers and diferulic acid. Cell walls of stem of the mutant contained a total of 17.3 mg g^?1 of these bound acids compared with 9.8 mg g^?1 for leaf sheath and 3.5 mg g^?1 for leaf blade: there was more than twice as much p-coumaric acid in cell walls of stem as in those of leaf sheath and more than seven times as much as in those of leaf blade. When cell walls of the stem from the mutant or the normal cultivar were treated with NaOH their degradability by cellulase was highly correlated with the amounts of phenolic components released by the alkali.     

Chemical composition,in vitro starch digestibility and amino acid analysis of a underexplored kidney bean (Phaseolus vulgaris. L.) grown in Chongqing,China

Chemical composition, mineral analysis, in vitro starch digestibility, and amino acid analysis of a kidney bean (Phaseolus vulgaris. L.), grown in Chongqing, China, were carried out in 2011. The results showed that the bean flour contained low reducing sugar (0.79%) and fat (2.72%), but high protein (24.8%) and starch (44.84%). Mineral analysis indicated high Mg and Ca contents with low Na/K ratio (0.04). The proportions of rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) were 39.64%, 41.46% and 18.90% respectively. And the variation in their proportions, along with prolonged heating time, showed increase in RDS, and decrease in SDS and RS, but the SDS + RS amount can still account for major parts (51.63%) of the total starch after a 90‐min pre‐cooking. Comparing the amino acid contents of the bean sample with recommended profile FAO/WHO/UNU (1985), the results fulfil the standard except threonine and lysine, whose contents are slightly lower than the requirements (0.93 and 0.85).     

Structure and digestibility of tissues in normal and brown midrib pearl millet (Pennisetum glaucum)

The tissues in leaf blades, midribs, sheaths and stems of normal (N), 5848, and two brown midrib (bmr) mutants, 5753 and 5778, of pearl millet (Pennisetum glaucum (L) R Br) were examined for structural characteristics related to digestibility. The anatomies of the various plant parts were not substantially different between N and bmr plants. The more rigid, lignified tissues such as vascular bundles in all plant parts and the rind of stems were not digested after incubation for 7 days in N or bmr plants, indicating that modifications in these tissues were not sufficient to affect biodegradation. Modifications in the digestible tissues resulted in faster and more extensive degradation in bmr plants, and these changes appear to be the most significant in relation to biodegradation. The parenchyma of midveins and stems, which occupies c 70 and 60% of the cross-sectional area of these respective parts, were the sites where modification in phenolics resulted in the greatest improvement in digestibility.     

Protein quality of some Nigerian feedstuffs. I. Chemical assay of nutrients and amino acid composition

The nutrient and amino acid composition of a range of Nigerian feedstuffs were studied by chemical analysis and column chromatography for amino acids. Nearly all feedstuffs studied showed low crude fibre value except the palm kernel meal and the African locust bean seeds which gave high values, range 8.1 to 12.3% and 8.76 to 12.64%, respectively. All the animal protein concentrates studied, namely, skim milk powder, blood meal and fish meal showed desirable feedstuff characteristics such as a low crude fibre content, high crude protein content and fairly high gross energy values, lysine, methionine and tryptophan were the amino acids in shortest supply in most of the feedstuffs.     

Amino-acid composition and mycology of Sekete, a fermented product from Zea mays L

The local procedure for preparing Sekete is described. The isolated microfungi, Aspergillus flavus Link., Cladosporium cladosporioides (Fres.) de Vries, and Alternaria tenuissima (Kunze) Wiltshire, were examined for various aspects of their physiology and biochemistry. Sekete is rich in important amino acids as alanine, leucine, tyrosine, and lysine, though proline and arginine are lacking. All the mycoflora isolated exhibited good secretion of extracellular enzymes. Pullulan, starch, soyabean meal, and corn steep liquor encouraged alpha-amylase production.     

Chemical,amino acid and fatty acid composition of Sterculia urens L. seed

The chemical, amino acid and fatty acid compositions of Sterculia urens seeds are reported. The cotyledons were found to be rich in protein (30.88%) and lipids (39.2%). The major amino acids in defatted Sterculia urens cotyledon flour (DSCF) were determined as glutamic acid, arginine and aspartic acid. Cysteine, methionine, tyrosine and histidine were observed in minor quantities. The ratio of essential to non-essential amino acids was observed to be 0.45. Among the essential amino acids, isoleucine was found to be higher than the reported FAO/WHO requirements. The GC-FID and GC–MS analysis revealed that the major fatty acids of the total lipid were stearic acid (31.72%), linoleic acid (28.83%) and palmitic acid (26.79%). Eicosadienoic acid (4.98%) and eicosatrienoic acid (2.96%) were also found in the total lipid.     

Chemical composition,amino acid content and protein quality of Canavalia spp. seeds

Canavalia ensiformis is a grain legume that offers good possibilities for its use, but reports on its chemical composition and nutritive quality are not readily available. This study presents chemical and nutritional data on C. ensiformis, C. gladiata and C. maritima grains. The three species varied in protein content mainly because of differences in crude fibre content. Protein varied from 26.9 to 22.4%, and crude fibre varied from 8.5 to 17.3%. This was due to differences in seed-coat percentage. The amino acid content in C. ensiformis and C. gladiata was essentially the same, and both were deficient in sulphur-containing amino acids but rich in lysine. Pressure cooking and roasting reduced lysine levels. Mineral content in the three species was essentially the same, with high potassium levels as is the case with most food legumes. Feeding trials indicated low nutritional quality for the raw grain, which was significantly improved by pressure cooking and roasting. Protein digestibility was 47.9%, and cooked and roasted samples had 76.4 and 78.7%, respectively. Both C. ensiformis and C. gladiata had the same protein quality (PER = 1.24), and it was significantly improved with methionine supplementation.     

Ruminal bacteria and protozoa composition,digestibility, and amino acid profile determined by multiple hydrolysis times

Microbial samples from 4 independent experiments in lactating dairy cattle were obtained and analyzed for nutrient composition, AA digestibility, and AA profile after multiple hydrolysis times ranging from 2 to 168 h. Similar bacterial and protozoal isolation techniques were used for all isolations. Omasal bacteria and protozoa samples were analyzed for AA digestibility using a new in vitro technique. Multiple time point hydrolysis and least squares nonlinear regression were used to determine the AA content of omasal bacteria and protozoa, and equivalency comparisons were made against single time point hydrolysis. Formalin was used in 1 experiment, which negatively affected AA digestibility and likely limited the complete release of AA during acid hydrolysis. The mean AA digestibility was 87.8 and 81.6% for non-formalin-treated bacteria and protozoa, respectively. Preservation of microbe samples in formalin likely decreased recovery of several individual AA. Results from the multiple time point hydrolysis indicated that Ile, Val, and Met hydrolyzed at a slower rate compared with other essential AA. Singe time point hydrolysis was found to be nonequivalent to multiple time point hydrolysis when considering biologically important changes in estimated microbial AA profiles. Several AA, including Met, Ile, and Val, were underpredicted using AA determination after a single 24-h hydrolysis. Models for predicting postruminal supply of AA might need to consider potential bias present in postruminal AA flow literature when AA determinations are performed after single time point hydrolysis and when using formalin as a preservative for microbial samples.     

Comparison of brown midrib sorghum-sudangrass with corn silage on lactational performance and nutrient digestibility in Holstein dairy cows

Total mixed rations containing brown midrib sorghum-sudangrass silage (bmrSS) or corn silage (CS) at either 35 or 45% of dietary dry matter were fed to Holstein dairy cows to determine the effect on lactational performance and nutrient digestibility. Twelve cows were assigned to 1 of 4 diets in replicated 4 × 4 Latin squares with 21-d periods. In vitro 30-h neutral detergent fiber digestion, measured before the start of the trial, was 46.0% for CS and 58.3% for bmrSS. Dry matter intake was greatest when cows were fed the 35% CS (23.4 kg/d) and 45% CS (23.2 kg/d) diets, was least when cows were fed the 45% bmrSS diet (17.6 kg/d), and was intermediate when cows were fed the 35% bmrSS diet (20.1 kg/d). The bmrSS diets resulted in greater body weight gain per 21-d period but similar body condition scores compared with the CS diets. Yield of solids-corrected milk (SCM) was similar among the diets. Efficiency (SCM:dry matter intake) was 28% greater for cows fed the bmrSS than those fed the CS diets. In vivo digestibilities of organic matter and crude protein were greater for the CS diets than the bmrSS diets, but total tract digestibilities of neutral detergent fiber and starch were similar among diets. Ruminal pH was greater when cows were fed the 45% bmrSS diet (6.58), was least when cows were fed the 35% CS (6.10) and 45% CS diets (6.13), and was intermediate when cows were fed the 35% bmrSS diet (6.42). The ratio of acetate to propionate was greater for the bmrSS diets (2.77) than for the CS diets (2.41), with no difference among diets in total volatile fatty acid concentrations (122 mM). In conclusion, cows fed bmrSS had greater efficiency of SCM production, higher ruminal pH, and greater acetate to propionate ratios than cows fed CS. With these diets fed in a short-term study, bmrSS appeared to be an effective alternative to the CS hybrid when fed at either 35 or 45% of dietary dry matter.     

Walnuts (Juglans regia L): proximate composition,protein solubility,protein amino acid composition and protein in vitro digestibility

Walnuts contained 16.66% protein and 66.90% lipids on a dry weight basis. Non‐protein nitrogen values ranged from 6.24 to 8.45% of the total nitrogen when the trichloroacetic acid concentration was varied within the range 0.25–1.0 M . Albumin, globulin, prolamin and glutelin respectively accounted for 6.81, 17.57, 5.33 and 70.11% of the total walnut proteins. Walnut proteins were minimally soluble at pH 4.0. The majority of total walnut protein polypeptides had estimated molecular weights in the range 12 000–67 000. The Stokes radius of the major protein in walnuts (glutelin fraction) was 66.44 ± 1.39 Å. Lysine was the first limiting essential amino acid in total walnut proteins as well as in the globulin and glutelin fractions. Leucine and methionine plus cysteine were the second limiting essential amino acids respectively for the prolamin and albumin fractions. Hydrophobic and acidic amino acids dominated the amino acid composition in all protein fractions. Native and heat‐denatured walnut glutelins were easily hydrolysed by trypsin, chymotrypsin and pepsin in vitro. © 2000 Society of Chemical Industry     

Comparative study of phytic acid content,in-vitro protein digestibility and amino acid composition of different types of flat breads

Phytic acid content of eight different types of leavened and unleavened flat breads was determined. It was highest in unleavened and non-fermented whole wheat chapati and lowest in the leavened and fermented white wheat flat bread roghni nan. The effect of baking conditions, bread composition and phytic acid content on in-vitro digestibility of protein was measured using a pepsin multienzyme pH stat technique. The amino acids released were separated by ultrafiltration. The rate of protein digestibility of flat bread and amino acid released depended upon the type of flour used, baking conditions, phytic acid content and other antiproteolytic constituents of breads. Leavening and fermentation of breads resulted in an increase of protein digestibility and availability of amino acids. Addition of soya flour increases the protein digestibility of breads whereas millet flour decreases it.     

Methane production,ruminal fermentation characteristics,nutrient digestibility,nitrogen excretion,and milk production of dairy cows fed conventional or brown midrib corn silage

The objective of this study was to examine the effect of replacing conventional corn silage (CCS) with brown midrib corn silage (BMCS) in dairy cow diets on enteric CH₄ emission, nutrient intake, digestibility, ruminal fermentation characteristics, milk production, and N excretion. Sixteen rumen-cannulated lactating cows used in a crossover design (35-d periods) were fed (ad libitum) a total mixed ration (forage:concentrate ratio = 65:35, dry matter basis) based (59% dry matter) on either CCS or BMCS. Dry matter intake and milk yield increased when cows were fed BMCS instead of CCS. Of the milk components, only milk fat content slightly decreased when cows were fed the BMCS-based diet compared with when fed the CCS-based diet (3.81 vs. 3.92%). Compared with CCS, feeding BMCS to cows increased yields of milk protein and milk fat. Ruminal pH, protozoa numbers, total VFA concentration, and molar proportions of acetate and propionate were similar between cows fed BMCS and those fed CCS. Daily enteric CH₄ emission (g/d) was unaffected by dietary treatments, but CH₄ production expressed as a proportion of gross energy intake or on milk yield basis was lower for cows fed the BMCS-based diet than for cows fed the CCS-based diet. A decline in manure N excretion and a shift in N excretion from urine to feces were observed when BMCS replaced CCS in the diet, suggesting reduced potential of manure N volatilization. Results from this study show that improving fiber quality of corn silage in dairy cow diets through using brown midrib trait cultivar can reduce enteric CH₄ emissions as well as potential emissions of NH₃ and N₂O from manure. However, CH₄ emissions during manure storage may increase due to excretion of degradable OM when BMCS diet is fed, which merits further investigation.     

Effects of hydrogen peroxide and of sulphite and humidity on the amino acid composition and digestibility of fish protein

Cooked saithe fillets were minced and treated with different concentrations of hydrogen peroxide for varying times. The amino acid composition of the protein was not affected except that methionine was oxidised to methionine sulphoxide. Apparent protein digestibility as determined with rats was slightly decreased at the highest hydrogen peroxide level. This effect was not predicted by a rapid enzyme test. Sodium sulphite added to freeze-dried saithe flesh which was kept at three different humidities, had little effect on the amino acid composition. The rationale for this part of the experiments was that auto-oxidating sulphite may oxidise methionine. In this case the sulphite seemed to protect methionine.     

澳洲坚果粕营养成分测定与氨基酸组成评价

目的:研究分析澳洲坚果粕营养成分的含量与组成。方法:采用氨基酸自动分析仪、凯氏定氮法及蒽酮-硫酸法等方法对澳洲坚果粕中的氨基酸、蛋白质、碳水化合物等营养成分进行了测定。应用氨基酸比值系数法,以WHO/FAO氨基酸参考模式为评价标准,对必需氨基酸的组成进行了评价。结果:澳洲坚果粕含脂肪17.22%、蛋白质24.90%、碳水化合物24.78%、氨基酸17种,总量为17.84%。其必需氨基酸的构成比例基本符合食品法典委员会(FAO/WHO)的标准,氨基酸的比值系数分(SRC)为86.95。结论:澳洲坚果粕营养丰富,人体必需氨基酸种类齐全,配比均衡,是有利于人体氨基酸营养平衡的优质食品原料。     

Characterization,amino acid composition and in vitro digestibility of hemp (Cannabis sativa L.) proteins

The protein constituents and thermal properties of hemp (Cannabis sativa L.) protein isolate (HPI) as well as 11S- and 7S-rich HPIs (HPI-11S and HPI-7S) were characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and different scanning calorimetry (DSC), and their amino acid composition and in vitro digestibility were also evaluated, as compared to soy protein isolate (SPI). SDS-PAGE analysis showed that the edestin (consisting of acidic and basic subunits, AS and BS) was the main protein component for HPI and HPI-11S, while HPI-7S was composed of the BS of edestin and a subunit of about 4.8 kDa. DSC analysis characterized thermal transition of the edestin component and the possible present form of different subunits. Except lysine and sulfur-containing amino acids, the essential amino acids of various HPIs met the suggested requirements of FAO/WHO for 2–5 year old infants. The proportion of essential amino acids to the total amino acids (E/T) for HPI (as well as HPI-11S) was significantly higher than that of SPI. In an in vitro digestion model, various protein constituents of various HPIs were much easily digested by pepsin plus trypsin, to release oligo-peptides with molecular weight less than 10.0 kDa (under reduced condition). Only after pepsin digestion, in vitro digestibility of HPIs was comparable to that of SPI, however after pepsin plus trypsin digestion, the digestibility (88–91%) was significantly higher than that (71%) of SPI (P < 0.05). These results suggest that the protein isolates from hempseed are much more nutritional in amino acid nutrition and easily digestible than SPI, and can be utilized as a good source of protein nutrition for human consumption.     

Chemical composition and amino acid content of chickpea seeds at different stages of development

Chickpea seeds at five stages of seed development were analysed for contents of nitrogen, ether extract, ash, crude fibre, β-carotene, amino acid, and several minerals. Moisture, β-carotene and ash content on a dry weight basis decreased steadily during maturation, but other major components did not change appreciably. All the essential amino acids except lysine, cystine and tryptophan decreased at 28 or 35 days after flowering, then increased at maturity. Lysine was relatively high at 14 days after flowering (immature stage) but dropped sharply thereafter to a nearly constant value. An overall decrease in the mineral content of the seed was observed as the seeds matured.     

Prediction of the amino acid composition in brown rice using different sample status by near-infrared reflectance spectroscopy

In this study, 279 samples of brown rice grains and their flour, selected from a larger original population, were scanned by NIRSystem model 5000 mono-chromator in these two kinds of sample status for near-infrared reflectance spectroscopy (NIRS) analysis. Spectral pretreatment method 2,8,8,1 combined with SNV + D scatter correction was found suitable for developing calibration equations for amino acids. Equations for total amino acid content and for all individual amino acids, excluding cystine, methionine and tyrosine, were developed with this spectral pretreatment method. These equations had low SECV (0.010–0.063%) and SEP (0.011–0.066%); with high 1 − VR (0.878–0.960), R² (0.837–0.947) and SD/SEP (2.421–4.333). The results suggest that equations for the thirteen amino acids from the two sample categories can be directly used to estimate the amino acid composition in brown rice. This indicates once more that NIRS is a powerful technology that could be very useful for the determination of amino acid content in breeding programs that involve brown rice as well as for quality control in the food industry.     

Subunit,amino acid composition and in vitro digestibility of protein isolates from Chinese kabuli and desi chickpea (Cicer arietinum L.) cultivars

The subunit, amino acid composition and in vitro digestibility of the two protein isolates (GCPI and ZCPI) from one kabuli and one desi chickpea cultivars, grown extensively in Xinjiang Autonomous Region of China, were investigated and compared with those of soy protein isolate (SPI). SDS–PAGE showed that GCPI and ZCPI had almost the same band components under the reduced and unreduced conditions, with only minor difference in relative quantity for some bands, but different from that of SPI. The sulphur-containing amino acids were the first limiting amino acids for all three protein isolates of GCPI (2.11 g/100 g), ZCPI (2.20 g/100 g) and SPI (1.99 g/100 g). Amino acid score of the three protein isolates could reach the FAO/WHO requirement (1990) for the essential amino acids for preschool children. The order of in vitro digestibility was GCPI (87.47%) > ZCPI (80.82%) > SPI (71.04%). Our results indicated that, compared with soybean protein isolate, Chinese kabuli and desi chickpea protein isolates had higher digestibility value, and chickpea protein, especially for kabuli protein, could be utilized as a good source of protein for human nutrition.