Evaluation of the protein quality of meat flour from the tollo shark (Squalus acanthias)

The protein quality of tollo flour evaluated by various biological methods, including digestibility, is reported. The product contained 91.52% crude protein and 69.86% true protein, the difference being non-protein nitrogen, mainly urea. Due to this reason the biological evaluations were carried out with different shark flour concentrations and evaluated at different lengths of time with each method. Diets containing 0, 3, 6, 9 and 12% shark flour were prepared and evaluated by the PER, NPR, and NGI methods. Casein was used as reference protein. The protein digestibility was 91.2%, not corrected for non-protein nitrogen. On this same basis, PER and NPR--at a protein level of 9.97% in the diet--were 2.58 and 2.05, respectively. The casein control diet gave a PER of 2.93 and an NPR of 4.52. NGI was calculated by using the non-protein diet, or without it, with values of 3.32 and 2.95, respectively. As expected, all values corrected for non-protein nitrogen were higher for protein digestibility. The differences were significant at the 5% level. Apparently, urea influenced negatively the biological evaluations. It can be concluded, therefore, that the tollo shark meat is of excellent quality.     

Use of sunflower (Heliantus annus, L.) in human foods. II. Enrichment of sunflower protein concentrate with fish and sesame flour

The first part of this study revealed that a sunflower meal submitted to thermic treatment resulted in a protein of better quality when supplemented with lysine, while the meal not subjected to thermic treatment, supplemented with methionine, did not increase its nutritional value. These data indicated, therefore, that the limiting amino acid in sunflower meal is lysine, and not methionine. Based on these findings, and in order to confirm previous results, fish flour (high in lysine) and sesame flour (high methionine) were used to enrich the amino acid pattern of the sunflower protein concentrate. Three diets were thus prepared at the 10% protein level, containing: Sunflower protein concentrate which provided 70% protein, plus sesame flour (30% protein). Sunflower protein concentrate with 70% protein, and fish flour (30% protein). Sunflower concentrate with 70% protein, sesame flour with 20%, and fish flour with 10% protein. These following conclusions were derived on the basis of the analysis of these results: Supplementation of sunflower concentrate with 30% sesame flour does not producer a product of high nutritional value, once again indicating that lysine and not methionine is the limiting amino acid. Supplementation of the sunflower protein concentrate with fish flour (high in lysine content) presents a protein efficiency ratio (PER), practically equal to that of the casein pattern.     

Use of earthworms as a protein supplement in diets for rabbits

The purpose of the present study was to evaluate the nutritive value of earthworms as protein feed in rabbit rations. Earthworm meal was obtained from Eisenia foetida and Lumbricus rubellus. Its proximate chemical composition, amino acid composition and protein digestibility in vitro were determined. In addition, growing rabbits were fed a diet containing 30% of the total protein as earthworm meal, diet which was compared with a control diet containing soybean meal as protein feed. Both diets were isocaloric and isonitrogenous. Feed intake, weight gain, feed conversion and apparent digestibility were measured. Results showed high protein (50.86%) and fat (10.16%) contents, and low fiber percentage (2.67%). Amino acids content including the essential, and in vitro protein digestibility percentage were similar to fish and meat meals and higher than soybean meal. There were no differences in feed intake, weight gain and feed conversion. Apparent digestibility was 5.09% higher (P less than 0.05) with the diet containing earthworm meal than with the control diet. It was concluded that it is possible to substitute 30% of the protein in the diet of growing rabbits, with earthworm meal, without any adverse physiological effects. Similar results to those achieved when conventional protein supplements are used for rabbit rations, were obtained.     

Enrichment of precooked white corn flour (Zea mays) with amaranth seed flour (Amaranthus sp.)

Three mixtures of precooked white corn flour with 10, 20 and 30% amaranth flour were prepared. The sedimentation and consistency of the mixtures differed from those of the white corn flour, but without altering the capacity of dough formation to prepare arepas. The protein, fiber, and ash contents were higher than those of the precooked white corn flour. The functional properties of water and oil absorption increased in 20 and 10%, respectively. During the three-month storage, the protein and fat contents were not altered. Acceptability tests of the arepas were carried out and results indicated that those mixtures prepared with 10% and 20% substitution levels were acceptable from the sensory point of view. The protein quality was analyzed in terms of protein efficiency ratio (PER), which proved to be higher than that of the commercial white corn flour (PER 1.93), and the apparent digestibility was 92%. As far as lysine is concerned, results showed that arepas prepared with the mixture containing 10% amaranth (1.6 g lysine/100 g protein) and 20% (2.0 g lysine/100 g protein) also proved to be higher than the commercial white corn flour arepas (0.7 g lysine/100 g protein). Based on the above findings, enrichment of commercial white corn flour with grain amaranth flour, prior to the preparation of arepas, a product of high consumption in Venezuela as part of the habitual diet, is recommended.     

Studies on a vegetable protein mixture based on peanut and soya flours

A vegetable protein mixture made up of 50% edible peanut flour and 50% full-fat soya flour and fortified with 1% each of 1-lysine and dlmethionine and adequate amts of essential vitamins and minerals has been developed. Two formulations, 1) unseasoned and 2) seasoned have been developed for use in sweet and savoury preparations; both the formulations keep well for more than 9 months at 37C when stored in hermetically sealed cans. The protein mixture contains 49.2% protein which possesses a PER of 2.80 and NPU of 72.3; these values compare favourably with those for skim milk powder. Growth studies on albino rats and feeding trials on school children have shown that the protein mixture has a significant supplementary value to poor cereal-based diets. The mixture fortified with methionine alone is equally effective as skim milk powder for the treatment of kwashiorkor.     

Utilization of protein-rich ethanol co-products from corn in tilapia feed

Corn distiller’s grains with solubles (CDGS), which is the residue from ethanol fermentation of corn, were incorporated in tilapia (a warm-water fish) diets that contained either 36% protein without fish meal or 32% protein with and without fish meal. A 103-day feeding study indicated that the three diets containing CDGS resulted in higher weights of tilapia than fish fed a commercial fish feed containing 36% protein and fish meal. The difference in weight gains between 32 and 36% protein diets was not significant. Incorporating fish meal (6%) in diet had no advantage over a diet without fish meal. Presented at the “Characterization and Utilization of Proteins” symposium, American Oil Chemists’ Society 85th Annual Meeting, May 8–12, 1994, Atlanta, Georgia.     

Elimination of toxic compounds, biological evaluation and partial characterization of the protein from jojoba meal (Simmondsia chinensis [Link] Schneider

The purpose of this study was to establish a new methodology to remove the toxic compounds present in jojoba meal and flour. Also, to perform the biological evaluation of the detoxified products and to chemically characterize the protein fractions. Jojoba meal and seed without testa were deffated with hexane and detoxified with a 7:3 isopropanol-water mixture which removed 86% of total phenolic compounds and 100% of simmondsins originally present, the resulting products had reduced bitterness and caused no deaths on experimental animals. NPR values obtained for diets containing such products were significantly different from those obtained with the casein control (p less than 0.05). Total protein was made up of three different fractions: the water-soluble fraction was the most abundant (61.8%), followed by the salt-soluble (23.6%), and the alkaline soluble fraction (14.6%). The nitrogen solubility curves showed that the isoelectric point for the water-soluble and salt-soluble fractions was pH 3.0, while that of the alkaline fraction fell in the range of 4.5-5.0. All fractions had a maximum solubility at pH 7.0. The methodology reported here, offers a viable solution to eliminate toxic compounds from jojoba meal or seeds, and upgrades the potential use of products such as animal feed or raw material for the production of protein isolates.     

Nutritive value of lupine and its potential as human food

The chemical composition and some indices of protein quality were measured in two species of sweet lupine Lupinus albus and Lupinus luteus grown at the Experimental Station in Gorbea, Chile: both samples showed a high protein content (39.5 and 44.6%). The protein efficiency ratio (PER) was measured in the rat and found to be 0.48 and 0.71, respectively, as compared to 2.57 for casein. Supplementation with 0.3% DL-methionine increased significantly those values, thus indicating that lupine protein is deficient in said amino acid. In another experiment the effect of cooking-extrusion on lupine flour (L. albus) was investigated and the chemical composition, protein efficiency ratio, methionine supplementation and digestibility of the protein were measured. The chemical composition was not changed but PER increased from 0.50 for raw lupine to 0.76 for processed lupine (P less than 0.05). Both values increased significantly with the addition of 0.3% DL-methionine. The protein digestibility of the supplemented lupine was not affected by the cooking extrusion process (76.5 and 77.8%, respectively). Supplementation of wheat flour with 5, 10, 15 and 20% lupine flour increased the PER of wheat flour from 0.92, to 1.39 for wheat flour supplemented with 10% lupine flour, and to 1.60 for the 15% level of the supplement. These studies seem to support the conclusion that sweet lupine is an interesting protein resource for human nutrition.     

Corn amino acid imbalance and the role of leucine excess

A study was conducted using two experimental models with weanling rats of the Wistar strain fed isocaloric diets containing 7% protein, Model I: two genetic varieties of maize were used; common corn (CC) or opaque-2-corn (M); and Model II: casein, 7% protein used without nicotinic acid in the diet in order to enhance the tryptophan limiting conditions like in the CC diet of Model I. PER, nitrogen balance, urinary urea and hepatic fat were determined. The results suggest that the imbalance of CC protein is related to lysine and tryptophan limitation, although the leucine excess content also plays an important role.     

Soy and corn flour precooked with microwaves and its use in the preparation of arepas]

Unhusked corn and soy grits were used as raw material, with a particle size ranging between 10 and 20 mesh (ASTM). The results obtained in this study reveal that microwave heating is effective in destroying the antinutritional factors present in soybeans. The trypsin inhibitor activity, in effect, was reduced to a 76% inactivation. The hemagglutinating titer was labile to the heating process, showing values of +8 to +3 for the full-fat soy flour and precooked soy flour, respectively. The quality of soy protein was measured by the protein efficiency ratio (PER) showing values of 2.63 for the precooked soy flour, and 2.46 to 2.21 for the precooked corn:soy blends (70:30 and 50:50). These uncooked blends present values of 1.17 and 1.04. The enriched corn:soy flour had a PER value of 1.60, in comparison to casein (PER = 2.90). The microwave heating improved the digestibility of the soy flour and blends. There were no significant differences (P less than or equal to 0.05) in relation to the functionality of the precooked flour and mixtures. The results obtained revealed that the applied process markedly improve the functional properties and nutritional value of the enriched flour, and of the "arepas" prepared from them.     

The protein quality of commercial products of texturized soybean protein and meat mixtures

The purpose of the present study was to evaluate the protein quality of eight commercial samples of texturized soybean protein (TSP) collected in the food markets of various Latin American countries. The study also included experiments designed to establish the limiting amino acids in those products, and studies to evaluate the process of texturization by extrusion cooking. Finally, experiments were also carried out to evaluate the effect of replacement of meat by TSP as well as the supplementary value of the latter to tortilla flour. The eight samples were characterized for their functional properties and protein quality. The results obtained indicate that all samples were different in density, water absorption, and nitrogen solubility. Likewise, all samples were different in their lysine, methionine and threonine content, with PER values ranging from 1.75 to 2.31. Protein quality standard value is 2.3. The amino acid supplementation studies showed a positive significant response to methionine addition, particularly in those products exhibiting low PER values. The addition of both lysine and threonine to the methionine-supplemented product, increased PER significantly. The data also demonstrated that replacement of more than 25% of meat protein by TSP protein decreased protein quality of the product, even when a TSP with an accepted protein quality value was used. This product was also found to supplement the quality of tortilla protein. Finally, it was established that the texturization process did not reduce the protein quality of soybean protein. Based on these results, it is concluded that the variability in the protein quality measured in the eight TSP samples was due to the initial quality of the soy flour texturized, which was already damaged before texturization. For this reason, it is recommended that Latin American countries establish TSP quality standards when this product is used as a protein extender for meat, and that appropriate systems be implemented for the quality control of such products.     

Effect of dietary concentration of Saccharomyces carlsbergensis yeast recovered from beer, in Warren male chicks

Six groups of 1-day-old Warren chicks (seven per group) were fed for 15 days on diets with the protein supplement made of mixtures of soybean protein and dried yeast Saccharomyces carlsbergensis recovered from beer. The purpose was to establish the maximum substitution level of the soybean protein isolate by dried yeast, with the least possible related metabolic effects. Each group was fed one of the diets containing 0%, 25%, 50%, 75% and 100% of the protein supplement based on yeast protein, substituting the soybean protein isolate. In order to estimate the NPR value of the yeast protein, a group which received a protein-free diet, was also included. Protein utilization and changes in both plasma and liver total lipids, triglycerides, cholesterol and liver and kidney uric acid, were determined. In triglycerides, cholesterol and liver and kidney uric acid, were determined. In the groups fed diets with 75% and 100% of yeast protein, decreased body weight gain and PER and NPR values were observed, as well as an increment in the liver and kidney uric acid concentrations, although the diet consumption was not substantially modified. Thus, protein utilization, measured as PER and NPR, was lower in these groups. Plasma uric acid was not modified in neither group. The plasma lipids were not altered at whatever yeast concentration, while in the liver, total lipids as well as triglycerides decreased when the dietary yeast was increased. Results indicated that when using whole yeast cells recovered from beer in pre-starting rations for chicks, 50% of yeast protein is the maximum substitution level.     

Significance of soya trypsin inhibitors in nutrition

Although recent evidence clearly indicates that trypsin inhibitors (TI) and low protein digestibility are the major factors responsible for the pancreatic hypertrophic and growth inhibitory effects of raw soybeans, there was uncertainty regarding the biological threshold level of TI at which these biological effects occur. To obtain such data, dehulled defatted flakes (10% dietary protein) containing graded levels of TI were fed to weanling rats for 4 weeks in two feeding trials. Normal pancreas weights were obtained in rats fed samples in which only 54 to 68% of the original TI of raw soya flour was inactivated. In partially toasted flakes with a nitrogen digestibility value of 77%, the average tolerance level of dietary TI activity that did not cause pancreatic hypertrophy was calculated to be 385 mg TI/100 g diet. TI tolerance level at maximum nitrogen digestibility of 85%, which did not significantly lower weight gain and reduce protein efficiencey ratios, was 260 mg TI/100 g diet. Continuous ingestion of high levels of TI (459 mg TI/100 g diet) in a 20% protein diet for 215 days did not inhibit growth nor cause pancreatic hypertrophy when compared to rats fed toasted soya flour diets. Pancreatic hypertrophy that occurs in rats fed raw soya diets containing up to about 1300 mg TI/100 g diet for 35 days was reversed by switching the rats to control diets or to 30% toasted flour. In long-term feeding studies, no pancreatic hypertrophy occurred in rats fed commercial edible-grade soya flour, concentrate, or isolate from time of weaning to adulthood (ca. 300 to 330 days). TI content of the diets ranged from 178 to 310 mg/100 g diet. Microscopic examination of the pancreas revealed no abnormalities. Gross appearances of heart, kidney, spleen and liver were normal. In long-term feeding, vitamin B-12 supplements were needed to provide optimum growth and to maintain body weight. Results of numerous chemical analyses, relatively short-term human tests and long-term animal feeding studies indicate that with proper control of manufacturing processes, soya protein products can be produced that, in mixed diets, have protein nutritional value approaching that of animal protein.     

Nutritional value of mung bean (Vigna radiata) as effected by cooking and supplementation

The study was conducted to improve the nutritional value of Mung (Vigna radiata) by supplementation with different kinds of meat. Diets were prepared using raw and cooked Mung and then cooked Mung was supplemented with poultry, mutton and beef at 10, 15, and 20 percent levels. Nutritional value of Mung was determined by chemical analysis as well as by rat assay. Mung had 25 percent protein and minor losses were observed during cooking. It had 1.21 percent lysine which was reduced by 43 percent on cooking. Other amino acids also showed losses during cooking. The Protein Efficiency Ratio (PER) of diet containing Mung was significantly reduced on cooking (1.86 vs 1.40). On the contrary cooking resulted in some improvement of Net Protein utilization (NPU) and True Digestibility (TD) of the Mung based diets. Twenty percent level of different meats showed better results in terms of PER, NPU and TD.     

Nutritional evaluation of table bread fortified with defatted soybean and sesame meals

The nutritional value of table bread fortified with 8% defatted soybean meal (DSBM), 12% DSBM and a mixture of 8% DSBM/4% defatted sesame meal (DSM) was assessed with in vivo and in vitro tests. Fortification with DSBM and DSM decreased protein digestibilities (P < 0.05) but improved essential amino acid scores (EAA) and overall nutritional value of the breads. Fortified breads contained twice as much lysine, and consequently a better protein efficiency ratio (PER) than the control bread. The PER of the 8% DSBM/4% DSM bread was similar (P > 0.05) to the 12% DSBM bread. The 8% DSBM fortified bread showed lower PER, amino acid and protein contents than breads fortified with 12% DSBM. In vitro procedures utilized to predict protein digestibilities and PER's provided a close estimation of in vivo results obtained from growing rats.     

Formulation and nutritive value of 2 milk substitutes based on sweet lupine (Lupinus albus, var. multolupa)

Two protein mixtures, A and B, based on sweet lupine, wheat flour and dried skim milk powder were formulated, bearing in mind the chemical and nutritional standards set by the National System of Health Services for protein mixtures used through the National Program of Complementary Feeding (PNAC) for preschool children. Both formulas contained 12% of sweet lupine flour, but they differed in their skim milk content, which was 15% in mixture A, and 10% in mixture B. Taking as reference value a content of 2% moisture, formula A contains 17.6% protein and mixture B, 16.4%, with a caloric content of 420 kcal/100 g for both of them. The amino acid score was 0.80 for both mixtures. The biological quality of the proteins of A and B, measured as protein efficiency ratio (PER), was 2.2 and 2.1, respectively. These values are not statistically different, although they are lower than the value of 2.5 obtained for casein (p less than 0.01).     

Functional and nutritional properties of modified proteins of sesame (Sesamum indicum, L.)

A study on the functional and nutritional properties of sesame (Sesamum indicum, L.) flour, concentrate and enzymatic hydrolysates, demonstrated that nitrogen solubility of the hydrolysates is improved, in water (85%) and at different pHs (91-95%), by the action of neutrasa 0.5L and alcalasa 0.6L, yielding a product with good emulsifying and improved foaming properties. Hydrolysates produced by the pH-stat method, then freeze-dried and spray-dried presented a PER of 1.1 and 0.9, respectively. The flour and the concentrate had PER values of 1.2. Supplementation of one of the hydrolysates with soya hydrolysate (1:1), improved the PER to a value similar to that of casein. Use of neutrasa 0.5L and alcalasa 0.6L enzymes, enhances the sesame protein solubility without modifying extensively the PER. Besides, it yields a dehydrated product with improved emulsifying and foaming properties.     

Supplementation of wheat flour with chickpea (Cicer arietinum) flour. II. Chemical composition and biological quality of breads made with blends of the same

Experimental bread made of wheat flour complemented with 5, 10 and 15% chick-pea flour was studied, using wheat bread as control. Samples were analyzed for their proximal chemical composition and amino acids content. Crude fiber and protein increased from 0.36% to 0.55%, and from 14% to 17.6%, respectively, when 15% chick-pea flour was added. The lysine content increased as the level of supplementation was raised. Biological quality of proteins was measured in rats as protein efficiency ratio (PER) as well as apparent digestibility resulting in an increase of PER values from 0.90 to 1.34 and small variations in bread protein digestibility. Bread nutritive value was significantly improved by adding chick-pea flour.     

Use of flour of pejibaye fruit (Bactris gasipaes H.B.K.) in bread making

Trial were conducted in Costa Rica in 1984 and 1985, to determine the possibility of substituting pejibaye (Bactris gasipaes H.B.K.) meal for wheat flour in bread. Utilization in three distinct mixtures was examined: 90:10, 85:15 and 80:20 percentage of wheat flour to percentage of pejibaye meal, respectively. The breads were made, and dough analyses were conducted at "Molinos de Costa Rica, S.A.", the country's principal flour mill. Chemical analyses were carried out at the University of Costa Rica. Results indicate a marked inverse relationship between both initial dough development time and dough strength maintenance, and the content of pejibaye meal present in the flour mixture. Consequent problems with sufficient dough expansion preclude utilization of this fruit meal for bread-making in proportions significantly greater than 10% of the total composite flour. The above-mentioned findings reflect the high nutritional value of the pejibaye fruit. Although the protein content is inversely correlated with the amount of pejibaye meal in the mixture, vitamin A and fat contents are positively correlated. This fact demonstrates that the utilization of pejibaye meal in bread-making may well be in some ways considered as a form of nutritional enrichment. As a final conclusion drawn from the results of analyses of the trials and sensory observations, the 90% wheat flour with 10% pejibaye meal mixture apparently was the optimum substitution level of the breads examined. The potential macroeconomic ramifications on the Costa Rican economy of producing and utilizing pejibaye meal in bread-making, are highly favorable.     

Effect of feeding muscovy ducklings different protein sources: Performance, θ-3 fatty acid contents, and acceptability of their tissues

One hundred Muscovy ducklings, 5-wk-old, from each gender were assigned to five dietary treatments. Each treatment of each sex contained two replicates of 10 ducklings each. Ducks were fed, from 4–9 wk of age, five isonitrogenous diets that differed in protein source, i.e., commercial protein concentrate (CPC), soybean meal, meat meal (MM), herring fish meal (HFM), and mixed herring fish and meat meals (HFM + MM). At the end of the experiment, four ducks per treatment were slaughtered for carcass evaluation and the fatty acid profiles of their meat, adipose tissue, and plasma. Final body weight of both sexes showed no difference among protein sources, although males fed CPC or MM diets had the largest weight gain. No differences in feed consumption and conversion between sexes were shown, although differences in θ-3 fatty acid consumption due to protein source were significant. Feeding fish meal reduced the sensory acceptance of meat, whereas the plant protein diet improved it. Total lipid and cholesterol contents of the meat of males showed no differences between protein sources. Correlation between θ-3 fatty acid consumption and plasma cholesterol was negative (r=0.91; P=0.03). Moreover, correlation between plasma cholesterol and plasma lipid was positive (r=0.97; P=0.01). Feeding fish meal enriched total unsaturated fatty acid of adipose tissues, θ-3 fatty acid of adipose and meat tissues, and total unsaturated fatty acid of thigh meat. Total unsaturated fatty acid and θ-3 fatty acid of blood plasma from females were also enriched by feeding fish meal-containing diets. This work was presented at the 21st World Congress and Exhibition of the International Society for Fat Research (ISF) October 1–6, 1995, The Netherlands Congress Center, The Hague.