Composition of sweet and bitter lupin seed hulls with observations on the apparent digestibility of sweet lupin seed hulls by young rats

Seed hulls from both sweet and bitter varieties of lupins (Lupinus angustifolius) have been analysed for constituent polysaccharides. The hulls contained 15 to 32% oxalate-soluble pectic polysaccharide, excluding pentose, 12 to 14% hemi-cellulose, 44 to 51% cellulose, 0.3 to 0.4% lignin, 2.7 to 3.8% protein and 2% ash. “Crude fibre” was 54.9%. In agreement with the low lignin values all of the hemicellulose was extractable with alkali without prior delignification and 70 to 80% of the polysaccharide in depectinated hulls was hydrolysed by cellulase plus hemicellulase, likewise without delignification. Sweet lupin seed hulls, added to a complete basal diet up to 40%, did not depress growth of young rats significantly; compensatory increase in food consumption occurred. With 60% hulls in the diet growth and food efficiency were reduced. Ground hulls did depress food and protein digestibility in direct proportion to their amount in the diet, possibly because of physical entrapment in the excessive bulk in the gut. The digestibility of the “crude fibre” of the hulls was 33% when the diet contained 20% hulls; this decreased to 22% when the content of hulls in the diet was increased to 60%.     

Nutritional potential and functional properties of sweet and bitter lupin seed protein isolates

Protein isolates were prepared from both sweet and bitter lupin seed flours by two different methods, i.e. by alkaline water extraction/isoelectric precipitation (P1) and by micellisation (MI), and studied with regard to nutritional quality and functional properties. Protein solubility of both lupin seed flours was increased as sodium chloride concentration increased up to 1.0 M, then decreased. The minimum protein solubility of bitter lupin seed flour was quite sharp at pH 4.5, while it exhibited a broad pH range of 4.3–4.9 for sweet lupin seed flour. No significant (P<0.05) differences were found between any isolates in their dry matter, fiber, lipids and moisture contents. Isolates-PI from both sources had significantly (P<0.05) higher crude protein and ash contents than their isolates-MI. Bitter and sweet isolates-PI had lower values of total essential amino acids and higher values of tyrosine, phenylalanine, threonine, tryptophan and valine than isolates-MI. There was no significant (P>0.05) difference between bitter isolates in their alkaloid contents, while both sweet lupin isolates were free of total alkaloids. Bitter lupin isolate-PI had significantly (P<0.05) lower tannins, but sweet lupin isolate-MI had a significantly (P<0.05) higher phytic acid content than other isolates. Isolates-MI from both sources had higher chemical scores than their isolates-PI. The first and second limiting amino acids were total sulfur amino acids and valine, respectively, for all types of isolates. Sweet lupin isolate-MI had a higher essential amino acid index and protein efficiency ratio than other isolates. The protein solubility index, fat absorption and emulsification capacities of both isolates-MI were significantly (P<0.05) higher than their isolates-PI. Both sweet lupin isolates had significantly (P<0.05) higher water absorption capacity than bitter lupin isolates. Sweet lupin isolate-MI had significantly (P<0.05) higher foam capacity and foam stability than other lupin isolates.     

The nutritional toxicity of sweet lupin (Lupinus angustifolius) seed proteins

The effects of raw sweet lupin (Lupinus angustifolius) meal on the growth and N utilisation of rats were determined in two ad libitum and two restricted‐feeding net protein utilisation (NPU) and five N balance experiments. Sweet lupin seed grown in Western Australia, obtained as meal, either unsupplemented (LMU) or fully supplemented with required amino acids (360 g kg⁻¹) (LMFS), was tested. Rats fed lactalbumin (130 g kg⁻¹) (LACT) were used as positive controls, while rats fed a non‐protein diet (NPC) were used as negative controls. In addition, seed protein, extracted at pH 7.0 with water and insoluble after dialysis at pH 7.0 (LPADI; 124 g kg⁻¹), was also used. The diets contained the same amounts of energy and protein and were supplemented with essential amino acids, vitamins and minerals to target requirements for rats. Inclusion of LPADI in the diet of growing rats caused urinary losses of N, almost all as urea, hypoproteinaemia and increase in body water that resulted in the lowest NPU values, N balance and growth rate as compared with other diets used. These rats developed atrophy of the spleen (low dry weight) and had a comparatively smaller thymus gland than those given raw meals. Furthermore, the LPADI fraction was shown by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS‐PAGE) to contain three polypeptides with molecular weights between 30 and 36 kDa which are similar to lectins obtained from Phaseolus vulgaris, Abrus precatorius and Ricinus communis. It is possible that the toxic protein component in the sweet lupin, which has negligible in vitro haemagglutination properties and is extremely toxic in vivo, exerts toxicity by interfering with protein synthesis in the liver, while the immune responses are secondary to azotaemia (high level of urea in the blood) or cytotoxicity action on lymphocytes. The unusual depletion of fat from the body, however, was due to the failure of absorbed amino acids to assimilate as proteins, creating dietary protein restriction and leading to lipolysis. It is therefore tentatively suggested that sweet lupin seed contains a lectin‐like protein that is concentrated in this fraction. Further purification and biological evaluation to establish the exact nature of this protein may be important. © 2000 Society of Chemical Industry     

Effects of casein,sweet white lupin and sweet yellow lupin diet on cholesterol metabolism in rats

The effect of lupin seed protein on rat cholesterol metabolism has been studied with diets high in fat (20% by weight) and containing cholesterol (1%). The proteins used were characterised by their lysine/arginine ratios (sweet white lupin (SWL) 0·5; sweet yellow lupin (SYL) 0·4; and casein 1·8), because the lysine/arginine ratio is one of the parameters suspected to decrease or increase plasma cholesterol depending on the ratio; the diets were also characterised by their total fibre content (casein diet 5%; SWL 22%; SYL 17%) because chronic fibre intake could improve glucose tolerance and modify glucoregulatory hormone levels. Methionine content of diets was balanced. Differences among the total serum cholesterol levels of rat groups fed these diets for 28 days were not significant. But, compared to the casein diet, both lupin diets increased plasma glucagon levels and faeces. Compared to casein and SYL diets, the SWL diet significantly decreased plasma triglyceride levels and the insulin/glucagon ratio, as well as unesterified liver cholesterol and plasma LDL triglycerides levels. The SYL diet significantly increased plasma glucose and insulin, as well as liver total cholesterol compared to the casein and SWL diets. The total fibre content of the diets could indirectly modulate the effect related to the insulin/glucagon ratio on cholesterol metabolism and explain the differences observed between the SWL and SYL diets. © 1998 SCI.     

Effect of lupin seed proteins on quality characteristics of fermented sausages

Lupin seed flours (LSF) and lupin seed protein isolates (LSPI) from a sweet (S) variety of Lupinus albus and a bitter (B) variety of Lupinus albus ssp. Graecus were used in the manufacture of fermented sausages at 2% level, based on the weight of meat and pork back fat, and hydrated to a protein/water ratio 1/4, to replace beef and pork meat on a protein to protein basis. LSF and LSPI had no effect (p>0.05) on the microbial counts, the pH, the moisture content and weight losses, the instrumentally measured colour numbers (L*, a*, b*), the firmness, the appearance and the sensory evaluated colour of fermented sausages. Fermented sausages produced with LSPI from the bitter variety had similar (p>0.05) sensory attributes to the control and lower (p<0.05) TBA values after the 28th day of storage. Fermented sausages produced with LSPI from the sweet variety had acceptable sensory attributes but TBA values higher than 1 mg of malonaldehyde/kg. LSF from both varieties had a high pro-oxidant effect and affected negatively the odour and taste of fermented sausages.     

Aqueous processing of lupin seed

Processing of two species of lupin seed by an aqueous extraction process has been explored and the resulting products have been examined. It has been shown that aqueous processing is an effective method for the separation of oil, protein and alkaloids of lupin seeds.     

Conditions affecting production of a protein isolate from lupin seed kernels

Conditions were investigated to determine the optimum processing parameters for preparation of a protein isolate from the ground, dehulled lupin seeds of Lupinus angustifolius. The extraction variables were: particle size (16–100 mesh); pH (2–11); extraction medium; solvent to lupin ratio (10:1 to 40:1); temperature (20–60^oC) and time (15–60 min). The isoelectric point of the lupin protein was found to be pH 4.5 with a protein solubility of greater than 90% above pH 8.0. Using 60–100 mesh ground lupin and extracting at pH 8.5 for 30 min, a protein isolate was obtained on acidification to pH 4.8 which was 89.4% protein compared to 34.0% protein for the original dehulled lupin. This protein isolate represented 19.8% of the starting material and 52% of the starting nitrogen. Similar results were also obtained when hexane defatted lupin was used. In this case the protein isolate had a protein content of 92.5%. The yield of protein isolate could be increased to 25.7% of the starting material if the extraction was repeated. The protein efficiency ratio for the protein isolate was 2.90 when supplemented with methionine.     

A simple procedure of lupin seed protein fractionation for selective food applications

A simple procedure aimed at fractionating the main proteins of lupin seeds is proposed. The protocol consisted of alkali extraction of all proteins and isoelectric precipitation of two classical storage globulins, namely conglutins and , and one albumin, conglutin . The supernatant of this separation contained conglutin , the other main lupin protein. Conglutin could easily be purified further by selective Zn²⁺ precipitation, leading to a more than eightfold enrichment with respect to the amount in the flour. Resuspension of the isoelectric precipitate in saline water/ethanol solution allowed us to isolate conglutin , a 2S sulphur-rich lupin protein, at a very high purity level. Conglutins and could not be separated further by simple procedures. Sodium dodecyl sulphate–polyacrylamide gel electrophoresis analysis confirmed the identities of the isolated protein fractions. The distribution of each separated protein type is close to that of the corresponding proteins in the seed. The results are discussed in view of the applicability of the method and the potential use of each protein type as a food ingredient.     

Germination alters the chemical composition and protein quality of lupin seeds

The chemical composition and protein quality of the kernels from Lupinus angustifolius seeds were compared with that for sprouts after 6 days germination. Germination resulted in an apparent increase in protein content from 395 g kg^?1 to 435 g kg^?1 DM. Fat and carbohydrate contents decreased. The oligosaccharide content of the sprouted lupin fell to a negligible level, while the phytate and alkaloid concentrations fell from 4.7 g kg^?1 to 1.6 g kg^?1 and from 0.72 g kg^?1 to 0.16 g kg^?1, respectively. The quality of lupin kernel protein was poor with a protein efficiency ratio (PER) of 1.45±0.15. Supplementation of kernel with DL-methionine (2.0 g kg^?1) increased the protein quality (PER = 2.87±0.17) to that of casein (PER = 2.86±0.18). Germination reduced protein quality (PER = 0.44±0.16), and did not improve apparent protein digestibility (APD kernel = 80.4%; APD sprout = 77.5%). Supplementation of sprout protein with DL-methionine (2.0 g kg^?1) increased the protein quality (PER = 2.57±0.20). The total sulphur-containing amino acid concentration of lupin kernel protein, 1.9 g per 16 g N was low, and decreased further to 1.3 g per 16 g N in the sprout, a drop of 32%. The results showed that germination of lupin seeds reduced the concentration of the anti-nutritive factors; however, it also reduced protein quality.     

籽瓜种子蛋白质组成及其提取工艺优化的研究

籽瓜种子蛋白质含量为36％～ 40％,其部分必需氨基酸达到或超过FAO的推荐标准.该资源目前主要是用于鲜食或炒制食用,研究系统评价籽瓜种子蛋白质的组成,并对其蛋白质的提取工艺进行优化,为籽瓜种子的开发提供理论依据.研究在单因素基础上,采用响应面方法,建立蛋白质提取因素与其提取率之间的回归关系.结果表明,籽瓜种子是一种优良的蛋白质资源,其最佳的提取工艺为提取液pH 11.5、温度61.5 ℃加热77 min,此时蛋白质提取率66.8％,该预测值与实测值相对误差仅为3.44％,试验结果真实可靠.     

Cholesterol-lowering effect of whole lupin (Lupinus albus) seed and its protein isolate

This study describes the hypocholesterolaemic effect of whole lupin and its protein in hamsters. The diets were: casein (control group HC), lupin protein isolate (group HPI) and whole lupin seed (group HWS). Diets from HPI and HWS promoted a significant reduction of total cholesterol and non-HDL cholesterol in the hamsters’ plasma as compared with HC. The true digestibility of HPI and HC groups were similar and differed significantly from the HWS one, which in turn showed a significant difference in total sterol excretion as compared to the former groups. Histological analysis of the liver revealed that animals fed on HPI and HWS diets presented a low level of steatosis (level 1) as compared to the ones fed on HC diet (level 4). Our findings demonstrate that protein isolate from Lupinus albus from Brazil has a metabolic effect on endogenous cholesterol metabolism and a protector effect on development of hepatic steatosis.     

Comparison of sweet white lupin seeds with soybean meal as a protein supplement for lactating dairy cows

Data were from 45 Holstein cows (23 multiparous, 22 primiparous) assigned by calving date and parity within groups to one of two isonitrogenous (16% crude protein) diets. The diets were 50% forages (corn silage, alfalfa silage) and 50% concentrate, dry basis. In diet A, soybean meal supplied 34.2% of total crude protein; in diet B, ground sweet white lupin seeds provided 37.9% of total crude protein. Cows were fed once daily during the experimental period (d 4 to 116 postpartum). Cows fed lupins consumed significantly less dry matter, produced 1.8 kg/d less milk (but not significantly different), and had lower milk protein percent. Milk fat and total solids percents were similar. Reasons for reduced intake of cows fed lupins were not evident. Traces of alkaloids (.005% dry basis) were present in diet B. Combined results of in vitro continuous culture fermentation and in situ degradation measurements indicated that crude protein from lupins was more degradable than that of soybean meal. Poor performances of cows fed lupins could be partly due to a reduced true protein supply to the small intestine.     

Semolina supplementation with processed lupin and pigeon pea flours improve protein quality of pasta

The objective of this work was to study the effect of processing (alcoholic extraction, fermentation and germination) on protein quality of lupin (Lupinus angustifolius L. var. Troll and Emir) and pigeon pea (Cajanus cajan L. var. Aroito) flours. Second, the effect of semolina supplementation with the processed legume flours on protein quality of pasta was also evaluated. For protein quality evaluation amino acid composition and chemical score (CS) were determined in raw and processed legume flours as well as cooked semolina pasta supplemented and non-supplemented with processed legumes. Alcoholic extraction did not cause important changes in the amino acid profile of lupin seeds. Certainly, sulphur amino acid content of ethanol extracted lupin flours was reduced but levels remained similar to those usually found in other legumes. However, fermentation and germination of pigeon pea seeds improved some essential amino acids and slight changes in CS indexes were observed. Moreover, semolina supplementation with processed lupin and pigeon pea flours improved protein quality of pasta as a result of higher CS and EAA levels compared to the control cooked semolina pasta. Therefore, ethanol extracted lupin, as well as fermented and germinated pigeon pea seeds are suitable protein sources for formulating new pasta products.     

Model salad dressing emulsion stability as affected by the type of the lupin seed protein isolate

Model salad dressing emulsions of an oil volume fraction of 0.50 were prepared using two types of lupin seed protein isolate (LSPI) differing in the method applied for their isolation and their protein composition. The dressing stability against creaming and droplet coalescence were studied and correlated with data on oil droplet size, rheological characteristics and the amount of protein adsorption at the droplet surfaces. Model salad dressing emulsions containing the isolate, mainly composed of lupin globulins, exhibited higher stability and more pronounced rheological characteristics compared to those prepared with the isolate enriched in albumins or with the mixture of the two isolates. The lupin albumins appeared to displace the globulins from the droplet surfaces, following competitive adsorption from mixtures of the two types of the lupin isolates. The results are discussed in terms of droplet interaction and rearrangement as they are influenced by the presence of the adsorbed protein molecules and aggregates which appear to determine long‐term stability of the emulsion systems. Copyright © 2006 Society of Chemical Industry     

羽扇豆蛋白的提取及性质研究

采用碱溶酸沉法对羽扇豆蛋白进行提取,利用响应面法对羽扇豆蛋白的提取工艺进行优化,得到最佳提取工艺是:pH为9.9,液料比15.7,温度为55.5℃,提取时间为30.4min,蛋白最佳得率为13.2%。按照Osborne蛋白分级提取方法对羽扇豆蛋白进行了精细分类,分别得到了羽扇豆清蛋白、球蛋白、醇溶蛋白和谷蛋白,其中球蛋白含量最高。羽扇豆蛋白的功能性质,包括溶解性、持水持油性、乳化性质,也进行了测定。     

Production of safflower protein isolates: Composition,yield and protein quality

The use of laboratory- and commercially-prepared safflower meal for the production of protein isolates is described. The isolates were obtained by micellisation and isoelectric precipitation techniques, the latter being the most efficient procedure. Previous treatments received by the meal, for example heating, influenced the protein recovery. In general, isolates produced by micellisation were more soluble than samples obtained by isoelectric precipitation. The colour of the protein isolates depended on the isolation technique and type of safflower meal utilised. All isolates had a similar amino acid composition and levels of in-vitro protein digestibility.     

Preparation of protein from lupin seeds

Different methods based on the protein extraction from undefatted and defatted lupin flour in alkaline medium and neutral environment using water and NaCl solution were investigated. The highest yield and protein content were obtained using combined extraction with water and NaCl solution. This method also resulted in the highest level of sum of the sulphur amino acids. Digestibility of protein of the lupin preparations was high.     

Bread quality and nutritional value of 'Marraqueta' and 'Hallulla' supplemented with full-fat sweet lupin flour (Lupinus albus cv. Multolupa)

'Marraqueta' and 'Hallulla' breads, widely consumed in Chile, were enriched with 6, 9 and 12% full-fat sweet lupin flour (FFLF) containing a small amount of alkaloids (0.025%) and 42.8% protein. Physical characteristics of the dough and the chemical composition and biological quality of the breads were investigated. Farinograph measurements showed that water absorption increased gradually from 61.3% for wheat flour to 79.8% for a blend with 12% FFLF. Developing time, weakening of dough and valorimeter value were not severely modified. Different levels of FFLF increased loaf weight as compared to all wheat bread. Protein content increased from 13.2% for the control to about 16% for 12% FFLF breads. Protein efficiency ratio (PER) values significantly increased (P < 0.01) for 12% FFLF breads: 'Marraqueta' from 1.10±0.09 to 1.59±0.12 and 'Hallulla' from 1.21±0.09 to 1.63±0.07. Apparent digestibility was about 86% and was not changed by FFLF inclusion up to 12%. Twelve per cent FFLF is a recommendable level to enrich 'Hallulla' and 'Marraqueta' in biological quality without affecting the farinological parameters. The results of acceptability tests will be published in due course.     

Production of guava seed protein isolates: Yield,composition and protein quality

The optimum conditions were determined for the preparation of protein isolates from ground, defatted guava seed flour. The isolates were obtained by micellisation and isoelectric precipitation techniques. The isoelectric point of guava seed protein was found to be pH 4.5 with a protein solubility of more than 85% above pH 9. Using 40–80 mesh particle size and extracting at pH 10 for 30 min, an isoelectric isolate was obtained by acidification to pH 4.5 which was 85.4% of the starting protein compared to 18.3% for micellisation protein obtained by twofold dilution with cold distilled water of 5% NaCl protein extract. The isolates were easily digested by the pepsin-pancreatin enzyme system and were comparable to casein. The amino acid composition showed that guava seed flour and isolates were deficient in sulphur-containing amino acids and in lysine, but contained the other essential amino acids in adequate levels. The micellisation isolate had higher fat absorption and emulsion stability than the isoelectric isolate, while other functional properties were almost similar.