Amino acid profiles and protein quality of cooked cassava leaves or ‘saka‐saka’

Cassava (Manihot esculenta Crantz) leaves form the main source of protein in a diet consisting of processed cassava roots as sole staple food in konzo‐affected areas of the Democratic Republic of Congo. Pounded cassava leaves were hydrolysed and analysed by HPLC before and after cooking to assess amino acid profiles and protein quality. An average of about 58% loss of total protein content was observed in five different cooked samples. The protein content in cassava leaves was high, an average of 285.9 g kg^?1 dry weight in the raw and 119.2 g kg^?1 dry weight in the cooked samples, but of poor quality, with sulphur amino acids as the most limiting amino acids. Lysine and leucine were also limiting amino acids in some of the raw samples. Lysine, histidine, leucine and isoleucine were limiting amino acids in the cooked samples besides the sulphur amino acids. The consumption of cassava leaves does not compensate the dietary deficiency of sulphur amino acids in the roots that are the staple food in konzo‐affected areas. Sulphur amino acids are essential for detoxification of the residual cyanogens remaining in insufficiently processed cassava roots. Cereals and legumes, as sources of sulphur amino acids and lysine respectively, should be promoted as part of the diet in those areas to prevent the paralytic neuro‐toxico‐nutritional disease konzo among the poor population. Copyright © 2003 Society of Chemical Industry     

Effect of grass hay substrate on nutritional value of Pleurotus ostreatus var. columbinus

Fruitbodies of P. ostreatus var. columbinus harvested from grass hay and wheat straw substrates were analyzed and compared in order to assess changes of their nutritional status depending upon cultivation substrate. The results showed that grass hay substrate increased significantly the protein content expressed as crude protein, digestible protein, protein precipitated with copper hydroxide or trichloroacetic acid and protein calculated from amino acid nitrogen. Protein content increase was likely, resulting from a significant increase of aspartic acid, arginine, glutamic acid, leucine, lysine and valine contents. Chitin content unfortunately increased significantly in Pleurotus mushroom grown on grass hay substrate. No significant difference was recorded in the case of acid detergent fibre, lipids, minerals and vitamins. In contrast, neutral detergent fibre, acid detergent lignin and sugar contents decreased in Pleurotus grown on grass hay.     

Determination of γ‐aminobutyric acid in Chinese rice wines and its evolution during fermentation

γ‐Aminobutyric acid (GABA) is a functional amino acid that is widely present in Chinese rice wine. In this study, high‐performance liquid chromatography coupled with ultraviolet detection (HPLC‐UV) was established for the determination of γ‐aminobutyric acid in 22 Chinese rice wines collected from the Shaoxing region of China. Furthermore, the evolution of GABA was studied in Chinese rice wine during primary and post‐fermentation process. Results showed that the HPLC method was reliable with good linearity, accuracy, precision and stability. Additionally, the GABA content varied significantly in the 22 Chinese rice wines, and the content was much higher in wine samples with long aging periods. Regarding the evolution of GABA in Chinese rice wine during the brewing process, the level slowly increased during primary fermentation. A decrease in GABA was observed in the wine at the early stage of the post‐fermentation process. However, a marked increase on the GABA content occurred in wine at the late stage of post‐fermentation. The findings from this study are that HPLC can be successfully applied to determine GABA in Shaoxing brewed rice wines, and further provide useful information on quality control of such wines. Copyright © 2017 The Institute of Brewing & Distilling     

Total hordatine content in different types of beers

Hordatines are phenolic secondary metabolites typical of barley. Hordatines withstand at least moderate processing, and thus they are also found in barley malts and beer. So far, no published data on the hordatine content has been available in beers or different styles of beer. The aim of this study was to produce information on the total hordatine content in beers and statistically compare the hordatine content of different beer types. In the current study, hordatines were analysed in 208 beers by high‐performance liquid chromatography equipped with a diode array detector (HPLC‐DAD). The average total hordatine content of all beer samples was 5.6 ± 3.1 mg L^?1 as p‐coumaric acid equivalents (PCAE), with a minimum values 0 to a maximum value 18.7 mg L^?1 PCAE. The total hordatine content correlated positively to the alcohol content in lagers, ales, stouts and porters, but not in wheat beers. There was no statistically significant difference in hordatine content in different types of beer, excluding the non‐alcoholic group of beers. It is noteworthy that non‐alcoholic beers also contained hordatines. More research would be needed to understand how parameters, such as mashing, should be chosen in order to achieve maximum recovery of hordatines in wort and beer.     

Antioxidant and chelating activity of Jatropha curcas L. protein hydrolysates

BACKGROUND: Antioxidant and chelating activities were determined in protein hydrolysates that were produced by treating a protein isolate of a non‐toxic genotype of Jatropha curcas with the protease preparation alcalase. RESULTS: 50 min protein hydrolysate with a degree of hydrolysis of 31.7% showed highest antioxidant and chelating activity. These activities were also determined in six peptidic fractions that were separated by gel filtration chromatography of the 50 min hydrolysate. The lower‐molecular‐weight peptidic fractions had the highest antioxidant and chelating activities, which correlated with a higher content in antioxidant and chelating amino acids such as tyrosine and histidine. CONCLUSION: Results show that J. curcas represents a good source of bioactive peptides. This may be important for the revalorization of defatted J. curcas flour, a by‐product resulting form oil extraction for biodiesel production. This is especially important in Third World and developing countries such as Mexico. Copyright © 2011 Society of Chemical Industry     

Gas chromatography of monosaccharides as O-isopropylidene derivatives. Analysis of hay,grass silage,and alkali-treated barley straw after mild and strong acid hydrolysis

Samples of hay, silage, untreated and ammonia-or alkali-treated barley straw were subjected to mild and strong acid hydrolysis, and the liberated monosaccharides were analysed by gas-liquid chromatography as their O-isopropylidene derivatives. From the mild acid hydrolysis, the total fructose content of the material and the amount of easily hydrolysed glucose were determined, allowing the content of non-structural carbohydrates to be estimated. In the same operation, the content of mannitol and arabinotol in the feed samples can be determined. From the strong acid hydrolysis, the total amounts of each aldose in the forage materials were determined.     

Determination of purine alkaloids and catechins in different parts of Camellia assamica var. kucha by HPLC‐DAD/ESI‐MS/MS

BACKGROUND: Kucha (Camellia assamica var. kucha) is a novel wild tea resource grown in China and a tea plant containing a sizable amount of theacrine (1,3,7,9‐tetramethyluric acid). High‐performance liquid chromatography (HPLC) analysis of purine alkaloids and catechins in young leaves of Kucha has been reported previously. However, the compositions of purine alkaloids and catechins in other parts of the plant remain unknown, and more information about the chemical constituents of Kucha is also necessary for further research and development of this new tea resource. RESULTS: Using HPLC with diode array detection coupled with electrospray ionisation tandem mass spectrometry (HPLC‐DAD/ESI‐MS/MS), three purine alkaloids, seven catechins and four non‐catechin phenolic compounds were identified or tentatively identified in Kucha. Purine alkaloids and catechins in leaves at different developmental stages, flowers, stems, pericarps and seeds of the plant were also quantified for the first time by the HPLC method, which was fully validated. Recoveries of the quantified compounds ranged from 96.67 to 104.33%. CONCLUSION: The results showed that the total contents of purine alkaloids and catechins were highest in young leaves of Kucha. Theacrine was detected in all parts of the plant and found to be most abundant in pericarps. Copyright © 2009 Society of Chemical Industry     

Evaluation of the fixed nitrogen-to-protein (N:P) conversion factor (6.25) versus ingredient specific N:P conversion factors in feedstuffs

BACKGROUND: The crude protein (CP) of feedstuffs is important as an indicator of essential and non‐essential amino acids for livestock. The protein (P) level needs to be known accurately, to minimize the feeding of excess nitrogen (N) and to reduce N pollution. Laboratory methods for determining N content report N from amino acids, but also N from ammonia and from non‐amino acid sources. The determined CP based on 6.25 × N level typically overestimates the true protein of feedstuffs. RESULTS: Determined ingredient‐specific N:P conversion factors k_A, k_P and k were not equal to the standard 6.25 factor. The k_A had the highest value in all ingredients, which leads to the estimation of specific crude protein (SCP), which is closer to true protein (the summation of the total amino acid residues from amino acid analyses). The SCP(k_A) was lower than CP and true protein in all ingredients, demonstrating that CP might overestimate the actual protein in feedstuffs. CONCLUSION: Based on data from 677 feedstuff samples from 2009, it is concluded that the mean k_A should be 5.68 for corn, 5.64 for soybean meal, 5.74 for corn DDGS, 5.45 for poultry by‐product meal and 5.37 for meat and bone meal. Copyright © 2011 Society of Chemical Industry     

Correlation between the amino acid content in rice wine and protein content in glutinous rice

Chinese rice wine is a fermentation product of glutinous rice that contains high levels of protein and amino acids. The turnover and catabolism of amino acids by fermentative microorganisms plays an important role in wine quality. The fermentation of Chinese rice wine, using 34 different varieties of glutinous rice, and the analysis of the protein and amino acid content of the resultant rice wine using precolumn derivatization via high‐performance liquid chromatography, are reported. A model of correlation and regression analysis of the protein content in the glutinous rice and the amino acids in rice wine was established. Results showed that the correlation coefficient between the total protein in glutinous rice and the total free amino acids in rice wine was 0.557, indicating a significant relevance. The population correlation coefficient between the total protein in the glutinous rice and the amino acids in the rice wine was high, i.e. R= 0.928. The correlation between the soluble protein content in the glutinous rice and the total free amino acids in the rice wine (or individual amino acids) was negligible. The total protein content in the rice variety was positively related to the sensory performance and free amino acid content of the resultant Chinese rice wine. Copyright © 2016 The Institute of Brewing & Distilling     

Influence of polyethylene glycol on the excretion and digestibility of amino acids in casein and tannic acid‐fed broilers

Using the precision feeding technique, an experiment was conducted to evaluate the influence of tannic acid (TA) and polyethylene glycol (PEG) on the excretion of amino acids and the apparent and true digestibilities of casein protein in broilers. Seventy‐two 9‐week‐old broiler cockerels grouped in nine treatments of eight replicates were fed warm water (50 mL, control birds), casein alone (12 or 18 g) or casein (12 or 18 g) with TA solution (4.5 g per 10 mL) or/and PEG solution (2 g per 10 mL). Total excreta were collected for 48 h and freeze‐dried. The amino acid content of casein and excreta was determined by reverse phase high‐performance liquid chromatography. In the absence of TA the digestibility of casein was almost complete. TA increased the excretion of amino acids to a varying extent (P < 0.01). Although the digestibility of all essential and non‐essential amino acids was adversely affected by the presence of TA, raising the amount of casein from 12 to 18 g improved significantly (P < 0.05) the apparent and true digestibilities of all amino acids. PEG reduced significantly (P < 0.01) the excretion of amino acids and improved significantly (P < 0.01) the amino acid digestibility of casein in TA‐dosed birds. However, the improvement was greater when the lower level of casein (12 g) was fed. Thus PEG might play an important role in inactivating dietary tannins in the gastrointestinal tract of birds and improving protein digestibility and utilisation, particularly when the diet is low or intermediate in protein. Copyright © 2007 Society of Chemical Industry     

Evaluation of bioactive properties of peptide isolated from Exocoetus volitans backbone

The aim of this study was to evaluate antioxidant, antiproliferative and antimicrobial properties of flying fish (Exocoetus volitans) backbone hydrolysed by three different enzymes namely papain, pepsin and trypsin. The in vitro antioxidant potencies of hydrolysates and purified peptides against 1, 1‐diphenyl‐2‐picrylhydrazyl, superoxide and hydroxyl radicals were evaluated by electron spin resonance spectroscopy. The peptic protein hydrolysate showed maximum free radical scavenging potential and lipid peroxidation inhibition and was further purified by DEAE XK 26/20 anion exchange chromatography followed by G‐25 gel permeation chromatography. The amino acid composition of potent purified fraction was determined by HPLC, contains essential and nonessential amino acids with glutamic acid (24.10%), lysine (23.62%), glycine (12.05%) and threonine (10.41%) as the dominant amino acids. The potent purified fraction was tested for cell cytotoxicity on Vero and Hep G₂ cell lines. It was found that fraction IIIb did not show any cytotoxic effect for Vero cell lines and exerted a significant antiproliferative effect on Hep G₂ cell lines.     

PURIFICATION AND PARTIAL CHARACTERIZATION OF A LECTIN FROM THE SEEDS OF DIOCLEA GUIANENSIS1

A lectin was purified from seeds of Dioclea guianensis by Sephadex G-50 affinity chromatography. Apparent homogeneity of the lectin was demonstrated by native polyacrylamide gel electrophoresis, chromatography on DEAE- and CM-Sepharose, and immunochemistry. The lectin showed a carbohydrate specificity for D-mannose (D-glucose)-binding, had a requirement for Ca^?2 and Mn^?2, contained no covalently bound carbohydrate and had an amino acid composition characterized by high content of aspartic acid, serine and threonine, and low levels of sulfur-containing amino acids. At pH 7.5 it exists as two species of molecular weight about 100 and 47 kD and in dissociating solvents three subunits of approximate size of 30, 18 and 12 kD were obtained. The lectin agglutinated erythocytes from rabbit and chicken but not from human, cow, sheep, goat or pig and was toxic to brine shrimp (Artemia salina) larvae. It was relatively heat-stable, retaining half of its original activity even after 90 min at 70°C.     

Comparative study of proximate composition and amino acid in farmed and wild Pseudobagrus ussuriensis muscles

The proximate composition and amino acid compositions of the muscle of wild and farmed Pseudobagrus ussuriensis were compared. The lipid content of the farmed fish was significantly higher, while moisture content was significantly lower, than those of the wild fish. Pseudobagrus ussuriensis protein has a well‐balanced amino acid composition. The percentages of total amino acids, essential amino acids, nonessential amino acids and delicious amino acids were significantly higher in the wild than those in farmed fish. The ratios of W_EAA to W_TAA (42.78%–43.02%) and W_EAA to W_NEAA (85.52%–87.74%) were comparable to the reference values of 40% and above 60% recommended by FAO/WHO. According to the amino acid scores, methionine would have been described as the first limiting amino acid, and Lys had the highest score for the protein in both wild and farmed Pseudobagrus ussuriensis. This study shows that Pseudobagrus ussuriensis under investigation have high nutritional qualities and are good protein resources.     

Proximate composition and biological activity of Chilean Prosopis species

The proximate and amino acid compositions of the leaves and pods of Prosopis chilensis and P tamarugo and the leaves of P alba have been assessed. The biological activity of the leaves and pods of the first two species as well as the leaves and exudate of P alba has been determined for free radical scavenging activity, xanthine oxidase inhibition and DNA binding. The best protein source among the forage trees was the leaves of P chilensis; P alba and P tamarugo leaves showed higher crude protein, fat and nitrogen‐free extract values than reported in previous studies. According to their amino acid profiles, all species surveyed are deficient in essential amino acids. The alkaloids β‐phenethylamine and tryptamine were isolated from P chilensis, and phenethylamine was detected in P tamarugo. At 0.50 mg ml⁻¹, both compounds showed DNA binding activity, with values of 18.5 and 11% respectively. The exudate of P alba showed a strong free radical scavenging effect. The activity was related with the total phenolics content, consisting mainly of catechin. © 2000 Society of Chemical Industry     

Chemical composition,protein fractionation,essential amino acid potential and antimetabolic constituents of an unconventional legume,Gila bean (Entada phaseoloides Merrill) seed kernel

Physical characteristics of pods and seeds, proximate composition, different protein fractionation, SDS‐PAGE analysis of proteins, amino acid composition, starch content, fatty acid profiles and various antimetabolic substances of Gila bean (Entada phaseoloides Merrill) were studied. The pod length and the number of seeds per pod ranged from 55 to 90 cm and from 5 to 11 respectively. The kernel comprised 66.1% of the seed weight (18.41 ± 1.14 g). The seed kernels contained 256.7 g kg^?1 crude protein, 108.1 g kg^?1 lipid, 27.3 g kg^?1 ash and a high content of carbohydrate (585.7 g kg^?1). The levels of potassium, phosphorus, zinc and iron were similar to those in conventional pulses. Among the different protein fractions of seed kernels, albumins constituted the major storage proteins (69.7%). The kernel proteins were rich in essential amino acids, particularly sulphur‐containing amino acids, and their values appeared to be higher than the FAO/WHO (1990) reference protein for a 2–5‐year‐old growing child and soybean, and comparable to hen egg. Seed kernel lipids contained high levels of unsaturated fatty acids, oleic and linoleic acids, which accounted for 83% of the total fatty acid recovered. The kernel exhibited high trypsin and chymotrypsin inhibitor activities (96.65 mg TI g^?1 and 30.02 CIU mg^?1 sample respectively) in addition to containing phenolics, phytic acid, lectins and oligosaccharides. Another major toxic constituent was identified as a group of triterpenoid saponins (3.21%), which had high haemolytic activity (HeU) against cattle erythrocytes and caused high mortality in fish. The in vitro digestibility of the kernel protein was low (67%). © 2001 Society of Chemical Industry     

Determination of proximate composition,fatty acid content and amino acid profile of five lesser‐common sea organisms from the Mediterranean Sea

Proximate composition, fatty acid and amino acid analysis of an echinoderm (Paracentrotus lividus), a crustacean (Penaeus kerathurus), a tunicate (Microcosmus sulcatus), and two gastropod molluscs (Littorina littorea and Patella coerulea) were determined. All organisms except M. sulcatus, were found to be good protein sources. P. lividus contained on average 15.1 g/100 g, P. kerathurus 15.6 g/100 g, L. littorea 8.3 g/100 g and P. coerulea 9.2 g/100 g protein. The crustacean contained high percentages of n‐3 fatty acids (28.3 g/100 g fatty acids), the tunicate high percentages of saturated fatty acids (62.2 g/100 g fatty acids) while the gastropod molluscs and the echinoderm had a balanced content of all fatty acid families. The most abundant amino acid in P. kerathurus, M. sulcatus, L. littorea and P. coerulea was glutamic acid (11.13 ± 0.9, 1.05 ± 0.3, 5.39 ± 0.3, 5.55 ± 0.8 g/100 g freeze‐dried sample respectively), while glycine was the most abundant amino acid in P. lividus (10.34 ± 1.0 g/100g freeze‐dried sample).     

Increased efficiency of wool growth and live weight gain in Merino sheep fed transgenic lupin seed containing sunflower albumin

The aim of this experiment was to assess, using sheep, the nutritive value of lupin seed transgenically modified to contain sunflower seed albumin. Eighty Merino wether sheep of mean live weight 32.3 kg were divided into two groups and fed 796 g dry matter (DM) day⁻¹ of a cereal hay‐based diet containing 350 g kg⁻¹ of either the transgenic or parent (unmodified) lupin seed for 6 weeks. Measurements were made of wool growth and live weight gain. After 6 weeks, half the sheep in each group were selected for a urine and faeces balance study in which organic matter (OM), nitrogen (N) and urinary purine metabolites were measured. Blood samples were taken from all sheep at the beginning and end of treatment and analysed for amino acids and plasma metabolites. A comprehensive chemical analysis of the grains showed that there was little difference between them in terms of most nutritional components, but the transgenic lupin seed contained a 2.3‐fold higher methionine concentration and 1.3‐fold higher cysteine than did the parent. There were no significant differences between grains in OM digestibility, rumen microbial protein synthesis or in sacco degradability of dry matter. Sheep fed the transgenic lupin grain had an 8% higher rate of wool growth (P < 0.01) and 7% higher live weight gain (P < 0.05) than sheep fed the parent grain. The sulphur (S) concentration of wool and the cysteine concentration of plasma were also higher in the sheep fed the transgenic lupin by 2.7% and 11.5% respectively (P < 0.05). Plasma methionine was increased by 10%, but the differences were not statistically significant (P > 0.1). Plasma urea N was lower in the sheep fed the transgenic grain than those fed the parent grain (6.5 vs 6.8 mmol l⁻¹, P < 0.05). The results show that genetic modification of a feed grain can improve its nutritive value for ruminants. The size and nature of the responses were consistent with the transgenic lupins providing more methionine to the tissues, a first‐limiting amino acid for sheep. © 2000 Society of Chemical Industry     

Comparison of extraction conditions for phenolic,flavonoid content and determination of rosmarinic acid from Perilla frutescens var. acuta

Perilla frutescens var. acuta has traditionally been used to treat disease including, depression, inflammation and tumors. Especially, the presence of rosmarinic acid can induce beneficial and health promoting effects. According to, this work was conducted to comparison of various extraction conditions (extraction process, solvent and time) of total phenolic, floavonoid and rosmainic acid contents from the leaves of Perilla frutescens var. acuta. Also, rosmarinic acid was determined in leaves of Perilla frutescens var. acuta by high‐performance liquid chromatography (HPLC) and the described method was ideally suited for rapid routine analysis. The highest yield of total phenolic, flavonoid and rosmarinic acid was shown 12.15 mg gallic acid equivalents g^?1 dry weight (DW), 7.23 mg rutin equivalents g^?1 DW and 3.76 mg g^?1 DW, respectively. The best condition for extraction efficiency of total phenolic, flovonoid and rosmarinic were found to be: ethanol concentration of 70%, extraction time of 24 h and extraction process of refluxed extraction.     

Proximate,mineral, amino acid,fatty acid,vitamin E,phytate phosphate and fibre composition of Mimusops zeyheri (Red Milkwood) seed

Mimusops zeyheri, an indigenous tree widely distributed in sub‐Saharan Africa, provides edible fruit. Research on the tree has focused on fruit pulp composition and uses. This study evaluated the nutritional potential of M. zeyheri seed by determining the proximate, fibre and phytate‐phosphate content, the amino acid and fatty acid profiles and vitamin E content of the seed. Dry matter, organic matter, crude protein, ether extract and ash constituted 91.1%, 88.3%, 9.3%, 25.6% and 2.8% of the seed mass respectively. Glutamic acid (1.29 g per 100 g) was the most abundant amino acid. Lysine and phenylalanine were low. Calcium (587.4 mg per 100 g) was the most concentrated macro‐mineral assayed. Gross energy value was 24.34 MJ kg^?1. Lipid yield was 21.3%. Oleic acid was the most abundant fatty acid. Vitamin E concentration was about 2 μg g^?1. Phytate‐phosphate content was 0.03%. Neutral detergent fibre and acid detergent fibre constituted 33.2% and 15.3% respectively. M. zeyheri seed could be exploited as a dietary energy supplement and an oil source rich in oleic acid.