Sweet lupin protein quality in young men

Biochemical Characterization of the Seed Quality of a Collection of White Lupin Landraces from Southern Italy

Lupin species provide essential nutrients and bioactive compounds. Within pulses, they have one of the highest contents of proteins and fibers and are among the poorest in carbohydrates. The Mediterranean region is an important cradle area of the origin and domestication of cultivated white lupin (Lupinus albus L.). In this work, we present the characterization of 19 white lupin landraces collected from several sites in southern Italy, characterized by different pedoclimatic conditions. The protein contents and electrophoretic patterns, total polyphenols, phytic acid, lipids and phosphorous content, and reducing and anti-tryptic activities have been determined for each landrace. The relationships of the compositional characteristics, the area of origin of landraces and between compositional characteristics and thermo-pluviometric trends that occurred in the genotype comparison field during the two-year period between 2019 and 2020 are compared and discussed. From a nutritional point of view, some of the analyzed landraces differ from the commercial reference. The panel of molecular analyses performed can help in building an identity card for the grain to rapidly identify those varieties with the desired characteristics.

Nutrient bioavailability of white lupine in complete feed for non-human primates

The article is devoted to the current world problem of vegetable protein deficiency, the solution of which can be white lupine. Particular attention is paid to assessing the bioavailability of nutrients from white lupine (Lupinus albus) in the body of non-human primates M. Mulatta. Because primates are phylogenetically closer to humans than other laboratory animals, which is very convenient for modeling and studying the digestibility of nutrients in diets. The purpose of the article is to study the digestibility of nutrients in lupine in the structure of complete feed and its effect on the biochemical parameters of the blood. As a result of the research, it was found that the inclusion of white lupine in the structure of the diet allows to improve the bioavailability of nutrients of complete feed, when included in the structure of the diet of white lupine in an amount of 10%, it made it possible to improve the digestibility of crude protein in relation to the control group by 5.5%, crude fat by 0.99%, crude fiber by 1.84%, BEV by 7.99%, crude ash by 4.67%, calcium (Ca) and phosphorus (P) by 6.99%, and 1.02 %. With the inclusion of 20% white lupine in the structure of the diet, it made it possible to improve the digestibility of crude protein in relation to the control group by 9.28%, crude fat by 6.5%, crude fiber by 5.98%, BEV by 2, 78%, crude ash by 11.28%, and absorption of calcium (Ca) and phosphorus (P) by 9.93% and 8.68%. At the same time, the results of hematological analyzes generally indicate the safety of consuming white lupine for 35 days.

Toxicological studies on plant proteins: a review

Nowadays, toxicological studies are contributing to human health more than ever. Reports on the toxicological studies of plant proteins, which are continuously growing in number in the literature, have been reviewed. Two important aspects are discussed: dietary safety evaluation, including toxicity tests and the maximum daily intake allowance, and the appropriate proportion in our daily diets of proteins from traditional foods and of new proteins from plant sources not traditionally employed as foods. Water hyacinth leaf proteins, sweet lupin proteins and canola proteins have not been shown to be toxic, although they are not traditionally employed as food proteins. These findings are very important for exploiting valuable new protein sources that are suitable for human or animal consumption and applicable to the food industry. Acutely toxic proteins, including lectins, ribosome-inactivating proteins, inhibitors of proteolytic enzymes and glycohydro-lases, have been isolated from plant materials and identified. Their toxicities and molecular characteristics have been described. The toxicity of proteins depends upon their specific native structures. Once they are denatured by appropriate treatment, such as heating, their toxicity can be reduced or even eliminated. These findings indicate that raw materials that contain this kind of toxic protein are not edible. However, after proper processing, they may be suitable for human or animal consumption. Although the toxicities of type 2 ribosome-inactivating proteins reported by different authors vary, the maximum dosages are still trace amounts.

An inhibitor from Lupinus bogotensis seeds effective against aspartic proteases from Hypothenemus hampei

The coffee berry borer, Hypothenemus hampei (Ferrari), is one of the most devastating coffee pests (Coffea arabica L.) worldwide. Digestion in the midgut of H. hampei is facilitated by aspartic proteases. This is the first report of an aspartic protease inhibitor from Lupinus bogotensis. The L. bogotensis aspartic protease inhibitor (LbAPI) exhibited a molecular mass of 12.84kDa, as determined by MALDI-TOF, and consists of a single polypeptide chain with an isoelectric point of 4.5. In thermal activity experiments, stability was retained at pH 2.5 after heating the protein at 70 degrees C for 30 min, but was unstable at 100 degrees C. The protein was also stable over a broad range of pH, from 2 to 11, at 30 degrees C. In in vitro assays, LbAPI was highly effective against aspartic proteases from H. hampei guts with a half maximal inhibitory concentration (IC(50)) of 2.9 microg. LbAPI inhibits pepsin in a stoichiometric ratio of 1:1. LbAPI inhibition of pepsin was competitive, with a K(i) of 3.1 microM, using hemoglobin as substrate. Its amino-terminal sequence had 76% homology with the seed storage proteins vicilin and beta-conglutin. The homology of LbAPI to vicilins from Lupinus albus L. suggests that they may also serve as storage proteins in the seed. LbAPI could be a promising tool to make genetically modified coffee with resistance to H. hampei.

Identification and characterization of a Bowman-Birk inhibitor active towards trypsin but not chymotrypsin in Lupinus albus seeds

The paper describes the purification, structural characterization and inhibitory properties of a trypsin inhibitor from Lupinus albus L., a leguminous plant believed to be devoid of any protease inhibitor. The protein has been isolated by a newly set-up procedure and characterized by direct amino acid sequencing, MALDI-TOF mass spectroscopy and circular dichroism. Inhibitory properties toward bovine trypsin and chymotrypsin, as well as its thermal and pH stabilities, have been also assessed. The inhibitor is 63 amino acid long (Mr 6858; pI 8.22) and it is capable to inhibit two trypsin molecules simultaneously, with a Kd of 4.2+/-0.4 nM, but not chymotrypsin. BLAST search against UniProtKB/TrEMBL database indicates that the inhibitor belongs to the Bowman-Birk inhibitor (BBI) family. The interest in these serine-protease inhibitors arises from the ability to prevent or suppress carcinogen-induced transformation, as shown in various in vitro and in vivo model systems.

Reevaluation of the protein requirement in young men with the indicator amino acid oxidation technique

BACKGROUND

The current estimated protein requirements are based on the nitrogen balance method, which has many limitations. An alternate approach is needed to permit a reevaluation of protein requirements.

OBJECTIVE

The objective was to determine protein requirements in men by using the indicator amino acid oxidation technique.

DESIGN

Eight healthy men randomly received graded protein intakes (0.10, 0.30, 0.60, 0.90, 1.2, 1.5 and 1.8 g kg(-1) d(-1)) as a crystalline amino acid mixture along with L-[1-(13)C]phenylalanine. The mean protein requirement was determined by applying a biphase linear regression crossover analysis on F(13)CO(2) data, which identified a breakpoint at the minimal rate of appearance of (13)CO(2) to graded protein intakes.

RESULTS

The mean and population-safe (recommended dietary allowance; RDA) protein requirements were found to be 0.93 and 1.2 g kg(-1) d(-1), respectively. These requirements are comparable with those estimated by the application of a biphase linear regression model to the data from nitrogen balance studies (0.91 and 1.0 g kg(-1) d(-1), respectively). These requirements are 41% and 50% higher than the current recommendations for the estimated average requirement (EAR) of 0.66 g kg(-1) d(-1) and the RDA of 0.80 g kg(-1) d(-1), as determined by applying a linear regression model where it intersects the zero balance line.

CONCLUSION

The indicator amino acid oxidation technique defined a protein requirement that is comparable with that estimated by the application of a biphase linear regression model to nitrogen balance data in the literature. Our data and the reanalysis of the preexisting nitrogen balance data suggest that the current recommended protein requirements are too low and require reassessment.

Nutritional evaluation of sweet lupin (Lupinus angustifolius): net protein utilization (NPU), nitrogen balance and fractionation studies

The effects of raw sweet lupin (Lupinus angustifolius) meal and its fractions on the growth and N utilization of rats were determined in two NPU and five N balance experiments. Sweet lupinseed grown in Western Australia, obtained as meal, unsupplemented (LMU), or fully supplemented with required amino acids (360 g/kg diet) (LMFS) was tested. In addition, six fractions were tested: aqueous non-dialysed extract at pH 7·0 (LPAND), dialysed extracts soluble (LPAD) and insoluble at pH 7·0 (LPADI), buffer-soluble extract at pH 7·0 (BUSOL), buffer-insoluble extract after dialysis at pH 7·0 (BUDI) and the residue (LMR) containing most of the material from meal insoluble in water and phosphate-citrate buffer. All diets based on fractions contained the same amounts of energy and protein and were supplemented with amino acids, vitamins and minerals to target requirements. Body N and lipid contents of rats fed on LMU and LMFS were reduced significantly in comparison with rats fed on positive lactalbumin (LACT) and non-protein diets (NPC) as negative controls. This wasdue in part to the lower retention of the absorbed N. As a result, the NPU and the biological value (BV) of sweet lupinseed proteins were less than expected. Urea-N outputs of the LMU- and LMFS-fed rats were also elevated. In contrast, true N and DM digestibilities of rats fed on LMU and LMFS were not significantly affected by the difference in the energy content of the diet. The replacement of lactalbumin in thediet with LPAND (196 g/kg), LPAD (148 g/kg), LPADI (124 g/kg), BUSOL (136 g/kg) or BUDI (119 g/kg) reduced dry body weight, N and lipid contents, NPU and BV compared with those obtained from the LACT control, even though the N and DM digestibilitieswere not significantly different. Inclusion of the residue fraction (170 g LMR/kg) had no apparent effect on any of the variables studied. Since sweet lupinseed had asmall amount of non-reactive lectin and LMR had some undesirable side-effects in these rats, it appears that the low nutritional value of LMFS for rats (NPU 0·62) despite the very high level of digestibility of its N, results from disturbances in N metabolism, and particularly from the low retention value of the absorbed N

The bioavailability and postprandial utilisation of sweet lupin (Lupinus albus)-flour protein is similar to that of purified soyabean protein in human subjects: a study using intrinsically15N-labelled proteins

Sweet lupin (Lupinus albus), a protein-rich legume devoid of anti-nutritional factors, is considered to have a high potential for protein nutrition in man. Results concerning the nutritional value of lupin protein are, however, conflicting in animals and very scarce in human subjects. Furthermore, where fibre-rich protein sources are concerned, the long-term nutritional results are often obscured, particularly since fibre-promoted colonic fermentation may bias the energy supply and redistribute N flux. We therefore studied, during the postprandial phase, the bioavailability and utilisation of lupin-flour protein in nine healthy men who had ingested a mixed meal containing intrinsically15N-labelled lupin flour as the protein source (Expt 1). The real ileal digestibility (RID) and ileal endogenous N losses (IENL) were assessed using a perfusion technique at the terminal ileum, and the N content and15N enrichment of ileal samples. Lupin flour exhibited a high RID of 91 (SD 3) % AND LOW IENL (5·4 (sd 1·3) mmol N/h). Postprandial dietary deamination was also assessed from body dietary urea and urinary dietary N excretion, and compared with results in nine healthy men following an isoenergetic meal containing a15N-soyabean-protein isolate with a similar RID, as a control (Expt 2). Postprandial dietary deamination was similar after lupin and soyabean meals (17 (sd 2) and 18 (sd 4) % ingested N respectively). We therefore conclude that lupin protein is highly bioavailable, even if included in fibre-rich flour, and that it can be used with the same efficiency as soyabean protein to achieve postprandial protein gain in healthy human subjects.

Lupin (Lupinus albus) protein isolate (L-ISO) has adequate nutritional value and reduces large intestinal weight in rats after restricted and ad libitum feeding

BACKGROUND

A protein isolate from white lupin (Lupinus albus; L-ISO) has potential as a novel human food ingredient, but its nutritional effects are unknown.

METHODS

We evaluated protein quality and effects on body composition in rats of isoenergic diets of L-ISO, lactalbumin, or casein with both restricted (10-day) and ad libitum (28-day)intake. The diets were equivalent in protein per se, but supplementation was used to balance essential amino acid levels.

RESULTS

In both studies, the rats consumed similar amounts of each diet, and no effect of diet on the gain:feed ratio was observed--though gain:N ratio and net protein utilization were slightly lower for the L-ISO diet. Lower large intestinal weights after the L-ISO than after the lactalbumin diet were observed in both studies. The L-ISO diet resulted in lowered body fat percentage in the 10-day study but in an elevated level in the 28-day study. Liver composition (DNA, RNA, glycogen, and fat) and plasma levels of some amino acids (His, Thr, Ala, Pro, Tyr, Val and Met) were affected by diet, but no effects on plasma lipid, glucose, or uric acid were observed.

CONCLUSION

The L-ISO diet did not affect feed intake and has adequate nutritional quality in rats whilst modifying large intestinal weight in a potentially beneficial manner--suggesting potential for this protein in human nutrition.

Meta-analysis of nitrogen balance studies for estimating protein requirements in healthy adults

BACKGROUND

The most recent international dietary protein recommendations for healthy adults are those developed and proposed by the 1985 FAO/WHO/UNU Joint Expert Consultation.

OBJECTIVE

The objective was to analyze available nitrogen balance data to establish new recommendations for the protein required by healthy adults.

DESIGN

Data were gathered from published nitrogen balance studies that had as their primary objective either the estimation of basal or maintenance requirements or the testing of the adequacy of specific nitrogen intakes in healthy adults. These data were synthesized to characterize the distribution of individual protein requirements; the effects of climate of the study site, adult age, sex, and dietary protein source on individual requirements; and the midpoint of and the variability between the protein requirements of healthy persons.

RESULTS

Data for 235 individual subjects, each studied at >or= 3 test protein intakes, were gathered from 19 studies. The median estimated average requirement (EAR) of nitrogen from these data was 105 mg N x kg(-1) x d(-1). Individual requirements were found to fit a log-normal distribution. The median EAR was estimated as the median of this distribution, 105 mg N x kg(-1) x d(-1), whereas the 97.5th percentile (the recommended dietary allowance; RDA) was estimated from the distribution of the log of the requirement (after correction of the total observed variability to remove within-individual variability) as 132 mg N x kg(-1) x d(-1). No significant differences between the climate of the study site, adult age class, sex, or source of dietary protein were observed, although there was an indication that women might have a lower requirement than do men.

CONCLUSION

This meta-analysis provides new recommendations for dietary reference values, ie, an EAR (median) and RDA (97.5th percentile) for healthy adults of 105 and 132 mg N x kg(-1) x d(-1) (0.65 and 0.83 g good-quality protein x kg(-1) x d(-1)), respectively.

Chemical composition, nutritive value, and toxicology evaluation of Mexican wild lupins

The nutrient composition, toxic factors content, and nutritional and toxicological value of Lupinus splendens, L. rotundiflorus, L. elegans, L. simulans, L. exaltatus, L. reflexus, and L. madrensis species from Mexico were analyzed. The seeds of these species were a good source of protein. All the species showed a high lysine and tryptophan content, though sulfur amino acids were limiting. Cyanogenic glycosides were absent, and lectins, trypsin inhibitors, and tannins were present in low concentrations. Lupanine was the major alkaloid in almost all the samples, although sparteine was the major alkaloid in Lupinus reflexus (26.63 mg/g of sample). Cytisine was not found in any of the studied lupins. L. reflexus showed the highest acute toxicity, and L. elegans exhibited no toxicity as evaluated using a mice model. The alkaloid was reduced by hot-water extraction. The protein efficiency ratio in water-debittered seeds was relatively poor (1.1-1.5). These results suggest that the wild lupins studied represent a potential protein supply, and they could be domesticated and used for animal feed if the alkaloids were eliminated and the protein was supplemented with methionine, or if the lupins were used in mixture with cereals.