Protein Quality of Cheddar Cheese Compared with Casein and Fabricated Cheese in the Rat

The protein quality of freeze-dried cheddar cheese, spray-dried cheddar cheese, freeze-dried fabricated cheddar cheese (with casein as the main protein source), and sodium caseinate was evaluated in rats using the protein efficiency ratio (PER) assay (AOAC procedures) in two feeding experiments with casein as the control. Biological evaluation of the products showed that PER values for freeze-dried cheddar cheese were significantly higher than casein (3.7 vs 2.5). Freeze-dried cheddar also had a PER value significantly higher than spray-dried cheddar cheese (3.7 vs 3.0). Freeze-dried fabricated cheddar cheese and sodium caseinate had PER values not significantly different from the casein control.     

Toxicity of water extracted rapeseed meal in the rat

The toxic effect of different concentrations of “detoxified” rapeseed meal (DRSM) obtained by 2 h lixiviation was studied. This preparation contained 0.02 % oxazolidinethiones (VTO) and no detectable isothiocyanates (ITC). It was fed for 4 weeks to weanling rats in amounts that provided from 0 to 100% of total dietary protein. The control diet provided 20% protein from casein. Another control group was fed crude rapeseed meal (RSM) to the same protein level. Growth rates and protein efficiency ratio (PER) were similar in rats fed DRSM and casein diets. The substitution of casein by increasing levels of DRSM did not modify PER. The weight of the liver, thyroid, heart, spleen, adrenals and kidneys was normal. In animals fed DRSM no histological changes were detected in the liver. The thyroid exhibited changes similar to, but of lesser severity than in animals fed crude RSM. It is suggested that other toxic compound(s) may be present in rapeseed meal that are not extractable by lixiviation. The need of further investigations of the effect of this “detoxified” product including functional studies before its extensive inclusion in animal or human diets is emphasised.     

Protein Quality of Selected Muscle Foods as Affected by the Exchange of Dietary Wheat Bran for Cellulose

The exchange of 8.4% neutral detergent fiber (NDF) of wheat bran for 8.3% NDF of cellulose in diets containing either beef, chicken, fish or casein as protein sources did not (P>0.05) alter feed consumption, weight gain or energy intake in the protein efficiency ratio (PER) bioassay with weanling rats. Higher (P<0.05) fecal nitrogen (N) excretions and lower (P<0.05) N digestibilities occurred for each protein source when wheat bran was exchanged for cellulose. The exchange also had no effect (P>0.05) on PER or net protein ratio (NPR) of casein or fish protein or on NPR of chicken protein. However, PER and NPR of beef and PER for chicken were reduced (P<0.05) when the dietary fiber was exchanged.     

Nutritional quality of storage proteins during germination of Indian bean (Dolichos lablab. var. lignosus) seeds

The dry Indian bean seed composed of starch is the major component (33%) and protein accounted for 25% of dry weight. The ability of germination to increase the nutritional quality of storage proteins was studied by germinating the Indian bean seeds for 0, 8, 16, 24 and 32 h and evaluated the nutritional quality through an in vitro protein digestibility (IVPD), protein efficiency ratio (PER), apparent and true digestibility. The IVPD of raw Indian bean seeds by pepsin alone was 60.12% and the digestibility by pepsin and trypsin together improved to 64.24%. The in vitro digestibility by both processes increased appreciably with germination and marked increase was noticed in the early stage of germination. The PER values followed the same pattern as the value of weight gain of rats fed with diets containing raw and germinated Indian bean. The lowest PER values were observed with raw bean diet. However, the value increased in rats fed with diets of Indian bean germinated for different intervals of time, reaching comparable PER values with the group maintained on casein diet. The true and apparent nitrogen digestibility of raw bean low being only 82 and 72%, respectively observed with casein diet. Diets with germinated bean protein showed a marked increase in both parameters, although the values were still less than that displayed by the casein fed rats. Germination is a simple biochemical enrichment tool and significantly improves palatability, digestibility and the nutritive utilisation of proteins in Indian bean seeds.     

An evaluation of protein quality of fenugreek seeds (Trigonella foenumgraecum) and their supplementary effects

The chemical composition and the nutritional value of protein of whole as well as solvent-extracted fenugreek seeds were determined. Fenugreek seeds are rich in protein (25·5%), fat (7·9%), unavailable carbohydrate (48%), mucilaginous matter (20%) and saponins (4·8%). The replacement of casein diet up to 10% by fenugreek seeds (extracted) did not produce any deleterious effect on protein quality of casein as assessed by protein efficiency ratio (PER), protein and dry matter digestibilities and net protein utilization (NPU). Further increasing the level of fenugreek did reduce these parameters. The extraction of seeds improved, and cooking did not alter the quality of fenugreek seed protein.     

Mineral Element Composition of Bovine Spleen and Separated Spleen Components

The content of 15 essential elements in whole beef spleens and in mechanically separated spleen pulp (MSS) and its connective tissue residue was determined by atomic absorption spectrophotometry. There were greater amounts of potassium, phosphorus, sodium, iron, and magnesium in MSS than in the whole spleen. Zinc was more concentrated in the residue. Upon cooking, larger quantities of potassium, phosphorus, sodium, iron, magnesium, and tin were noted in MSS than in the raw samples. Content of potassium, phosphorus, sodium, tin and zinc also increased in cooked whole spleen samples as compared to uncooked samples. Silicon content decreased with cooking in both the MSS and whole spleen samples.     

Rat bioassay of the protein nutritional quality of soy-fortified sorghum biscuits for supplementary feeding of school-age children

BACKGROUND: Protein–energy malnutrition (PEM) remains a major deficiency disease among children in developing countries. The protein nutritional quality of soy‐fortified sorghum biscuits was evaluated with respect to their potential as a protein‐rich supplementary food. Three isonitrogenous diets based on 50:50 ratio decorticated sorghum:defatted soy flour biscuits, 100% sorghum biscuits, casein, and a protein‐free diet were fed to male Sprague Dawley weanling rats. RESULTS: Protein efficiency ratio (PER) for the sorghum–soy biscuit diet was equivalent to the reference casein diet, and zero for the 100% sorghum diet. Faecal bulk for 100% sorghum diet was 1.5 times higher than sorghum–soy and casein diets. True protein digestibility of the three diets was high—88–95%—agreeing with previous rat studies with sorghum. Biological value and net protein utilization of the sorghum‐soy biscuit diet were similar to the casein diet, but lower than the 100% sorghum biscuit diet CONCLUSION: Notwithstanding limitations of rat bioassay for assessing sorghum food protein quality, the high PER of defatted soy flour‐fortified sorghum biscuits (sorghum:soy 50:50 ratio) indicates they have considerable potential as a supplementary food to young children to alleviate PEM. Copyright © 2011 Society of Chemical Industry     

Effect of soy protein supplementation on the nutritive value of ‘gari’ (farina) from Manihot esculenta

The supplementary role of soy protein on cassava (Manihot esculenta) “gari” or farina was studied in 35 day-old albino rats of the Wistar strain (n=6 per group) for 10 days. Gari was supplemented with soy beans at 10 and 15% soy protein levels to produce “soy gari” and the performances of rats fed the test diets compared with those on a 10% casein diet. Protein efficiency ratio (PER), Net protein utilization (NPU), true digestibility (TD) and biological values (BV) were the parameters used to assess the nutritional performance of the diets based on weight gains and nitrogen balance. The PER for 10% casein, 10 and 15% soy protein-supplemented gari groups were 2.31, 1.85 and 1.94 respectively, while the corresponding values for NPU were 71.9, 65.8 and 64.1, respectively. The TD values for the 10% casein, 10 and 15% soy protein-fed rats were 97.2, 91.9 and 90.0, respectively, while the corresponding values for BV were 73.9, 70.9 and 71.5. The PER, NPU, TD and BV for 10% casein diet were significantly superior (P<0.05) to those of the soy gari diets which gave NPU, TD and BV values 89–97% of those of the casein diet. There were no significant differences (P>0.05) in these parameters between the 10 and 15% soy protein supplementation. Soy gari is safe to the consumer, because the procedures involved in processing soy beans and cassava ensure the elimination of toxic anti-nutritional factors known to impact negatively on nutrient availability, metabolic processes and growth. It is suggested that the consumption of soy gari at 10% soy protein supplementation be promoted in gari-eating areas, to ameliorate the endemic problems of protein deficiency disorders.     

FOOD PROTEIN FROM MEAT AND BONE MEAL

SUMMARY— Studies were undertaken to develop a nutritious and aesthetically attractive protein concentrate from commercial meat and bone meal. Flotation in carbon tetrachloride was used to separate meat residues from the bulk of the bone. The meat residues had moderate nutritional merit in rat feeding trials. Further improvement was achieved by size separation or by base extraction. The finer fraction from size separation had a more favorable amino acid balance and gave better growth rates and protein efficiency ratios (PER) than did the unfractionated material. Growth rates increased markedly as the amount in the diet was increased to give 15 and 20% protein. It had more than an additive effect on growth and PER as a supplement to wheat flour or whole corn. Extraction with base improved amino acid balance, growth response and flavor. Addition of 9% of the base-extracted material to rice or biscuits had little effect on flavor; a gray-red color remained prominant. Overall yields of the base-extracted material starting with meat and bone meal were about 34%. The protein content of the product was about 88% on a dry weight basis. Its PER when 2% methionine was added was 75% of that of casein (without added methionine) in a rat feeding experiment. The cost of production is estimated at about $0.13/lb when allowance is made for methionine addition and for sale of residues from the production process as an animal feed supplement     

Nutritional Properties and Metabolic Studies of Acylated Beef Heart Myofibrillar Proteins

Beef heart myofibrils were acylated with several concentrations of acetic (AA) and succinic (SA) anhydride, and digestibility and utilization of the myofibrillar proteins were determined. Results for in vitro hydrolysis of the untreated and acylated proteins varied, depending on the enzyme(s) used in the analysis. Rat protein efficiency ratios and net protein ratios for untreated (PER = 2.83, NPR = 116) and acetylked (PER = 2.55, NPR = 110) proteins were greater than for casein (PER = 2.50, NPR = 100), whereas values for succinylated proteins (PER = 2.36, NPR = 87) were less than for casein. Most of the radioactivity recovered after 24 hr from rats fed ¹⁴C-acylated myofibrillar proteins was in expired CO₂; 62.8% for ¹⁴C-acetylated and 45.8% for ¹⁴C-succinylated proteins. Rats acclimated to an acylated protein diet for 28 days showed improved metabolism of ¹⁴C-acetylated protein and decreased metabolism of ¹⁴C-succinylated proteins; 75.7% and 38.1% recovery as expired CO₂, respectively.     

Nutritional Evaluation of Breadfruit-containing Composite Flour Products

Composite flours containing wheat, breadfruit flour and soy protein, whey or peanut meal were formulated and incorporated into western style bread and biscuits. Bread containing 10% breadfruit flour and 5% whey, and biscuits containing 10% breadfruit flour and 5% soy protein were judged most acceptable in flavor, color, and texture. Breadfruit flour contained 4.4% protein and was lower in sulfur containing amino acids and higher in lysine than wheat flour. Breadfruit containing bread and biscuits had low amino acid scores. The protein efficiency ratio (PER) of the biscuit product, however, was similar to that of the casein control while the PER of bread was significantly lower. Results suggest that acceptable products can be made with composite flours containing 10% breadfruit flour.     

Protein Efficiency Ratio and Amounts of Selected Nutrients in Mechanically Deboned Spent Layer Meat

Three types of mechanically deboned spent layer meat (MDSL) were found to have adjusted protein efficiency ratios (PER) equivalent or superior to a standard (casein) diet. These same materials proved to be good sources of calcium, iron and zinc. Percentage protein ranged from 15.39 for MDSL from whole spent layers to 16.55 for MDSL from spent layer frames with wings. Fat levels were highest for whole birds (20.41%) and lowest for frames without skin (16.84%). High levels of unsaturated fatty acids were found to be associated with these products.     

Development and testing of protein mixtures based on blood and collagen

Using the results of the chemical amino acid analyses of the unconventional proteins blood, collagen and wool and the conventional proteins soya, maize and casein, protein mixtures were developed. The quality of the protein mixtures was estimated in feeding experiments with growing male Sprague-Dawley rats and expressed as protein efficiency ratio (PER). Different blood parameters and the weight of some organs were also recorded. Blood, collagen and wool protein are very poor in different essential amino acids, therefore their quality is very low, it can however be significantly improved when they are fed in mixtures with other animal or plant proteins of higher quality. In mixtures of three components only containing blood (10--40%), collagen (10--25%) and casein (50 to 70%) the deficit in the content of essential amino acids cannot be compensated. Rats fed with such diets showed, however, decreased food intake and depressed growth. The relative PER values of those mixtures were 44--69% of that of casein. The best supplementing effect on the imbalanced amino acid patterns was achieved when the protein mixture was developed from 4 or 5 different proteins. The quality of these five-component-mixtures amounted to 94--100% of that of casein. In these mixtures the percentage of casein in the protein mixture amounted to only 35% and soya or maize to 15%. Exactly 50% of the protein supply could be derived from hydrolysates of the unconventional proteins blood, collagen and wool.     

Relative Protein Efficiency Ratios for Wheat-Based Breakfast Cereals

Male weanling rats were subjected to standard 28-day PER trials following the outline by the AOAC (1984) except that the diets contained 8.5% protein (N × 6.25) as one of six wheat-based breakfast cereals, white flour, whole wheat flour or casein. One of the cereals was an extrusion puffed product, three were flaked and toasted cereals and two were extruded cereals. Of the two extruded cereals, one was lightly toasted and the other was more heavily toasted. Relative PER (R-PER) was lowest for the puffed cereal (- 15.3) and highest for the extruded-lightly toasted cereal (69.9). R-PER for the flaked cereals ranged from 1.7 to 16.3; the other extruded cereal had a R-PER of 2.8 and each of the two flours had a R-PER of 42.9.     

NUTRIENT CHARACTERIZATION OF COLOR MODIFIED AND UNALTERED FLAKED TURKEY THIGH MEAT

Flaked, skinless and boneless turkey thighs were successively washed in 0.03M sodium phosphate buffers at pH 5.8, 7.4 and 8.0. Proximate, mineraland riboflavin composition, as well as protein efficiency ratio (PER) and apparent digestibility (AD) using the rat bioassay technique were determined for three replications. The color modified tissue (CMT) had a higher (P=0.0429) moisture content and less crude protein and ash (P = 0.0527 and 0.0047, respectively) than flaked thigh (THI). Percentage of iron, magnesium, phosphorous, potassium and manganese decreased (P=0.0187) after color modification. Calcium, zinc and copper concentrations did not change (P=0.1184) and sodium increased (P = 0.0058). Riboflavin was reduced by 30%. The PER of CMT was lower (P = 0.0318) than THI, but higher (P=0.0001) than either casein or egg albumen diets. AD of CMT was 90.7% which is comparable to other meat products. Although color modification was quite visible, it did not have a deterious effect on protein quality.     

Effects of different levels of palm oil and sulphur in cassava-based diets

The effects of different levels of palm oil and sulphur on the nutritive value of a cassava leaf protein diet was investigated using rats. With 40% cassava and no palm oil, the protein efficiency ratio (PER) and net protein utilisation (NPU) were very low (0·3 and 23·8, respectively) but the true digestibility was the same as that of the casein control (95·0%). With 5% palm oil there was no improvement in PER but both the NPU and biological value (BV) were increased appreciably (38·1 and 40·3, respectively). The best result was obtained with 10% palm oil, with which the PER was more than doubled (0·7) and there were similar increases in both the NPU and BV (46·6 and 48·9, respectively). Cassava at the 40% level was supplemented with various sources of sulphur—i.e. methionine, sodium thiosulphate, elemental sulphur, sodium sulphate and ferrous sulphate. With methionine, the PER, compared with the control (0·7), was more than trebled (2·2) and the NPU and BV were also significantly increased (72·6 and 83·3, respectively). Elemental sulphur gave a PER of 1·8 whilst sodium sulphate and ferrous sulphate gave 1·9. The lowest PER was obtained from sodium thiosulphate (1·1). The importance of palm oil and sulphur donors in cassava-based diets is discussed.     

Effect of Washing on the Nutritional and Quality Characteristics of Dried Minced Rockfish Flesh

Yield and nutritional characteristics of unwashed and washed minced rockfish flesh and fillets were determined. The yield of fillets from whole fish was 26% compared to 43% for minced flesh. Washing minced flesh resulted in a 37% loss of solids. The greatest reductions were found in the ash (80%) and lipid (65%) levels in the washed flesh. Most of the sarcoplasmic proteins were lost during washing, but 77% of the total protein (N × 6.25) was recovered in the washed fraction. Washing minced flesh did not affect the amino acid composition, and PER values for all three fish treatments were higher than the casein reference. The rapid formation of trimethylamine and dimethylamine in the dried fillets and dried minced unwashed flesh may explain the development of off-flavors in wafers containing 10% dried fish after 8 wk of storage at 30°C.     

Hydrothermal Cooking Affects Protein Efficiency Ratio and Zinc Bioavailability of Soymilk-Based Diets in Rats

Hydrothermally cooked (HTC) and conventionally processed soymilks were compared with respect to protein efficiency ratio (PER) and zinc bioavailability in Sprague-Dawley rats fed isocaloric, isonitrogenous diets. When dietary zinc was 50 mg/kg, PER (mean ± SD, n = 12) was greater for HTC (processed 20 sec) (2.69 ± 0.34) than for conventional soymilk (2.39 ± 0.17). When dietary zinc was 20 mg/kg, PER (n = 10) was less for HTC processed 40 sec (1.86 ± 0.17) than for conventional soymilk (2.08 ± 0.19). Processing (HTC vs conventional) did not affect zinc bioavailability by the slope ratio bioassay procedure. PER of HTC processed 20 sec was higher than that of reference casein and conventional soymilk when dietary zinc was near recommended levels; pancreatic hypertrophy was not observed.     

Protein supplementation of broad beans with sesame

Feeding experiments with weanling rats indicated that the protein of broad beans (Vicia faba var. major) and sesame (Sesamum indicum) are mutually supplementary. A standard diet in which 75% of the protein was provided by broad beans and 25% by sesame had a protein efficiency ratio (PER) of 2·36 compared to a casein PER adjusted to 2·50. A similar diet in which broad beans and sesame contributed equal amounts of protein had a PER of 2·41. The PER of broad beans was 0·99 and that of sesame 1·55.     

Effect of hydrochloric acid treatment of palm kernel for dehulling on the nutritional quality of kernel protein

The effect of hydrochloric acid treatment for the dehulling of palm kernel on the nutritional quality of its protein was studied and compared with that of untreated kernel protein and casein. Rats fed a treated defatted kernel protein diet had slightly lower gains in body weight (59·5 g) when compared to those fed a casein diet (64·2 g), while the gains in body weight in the animals fed untreated kernel protein diet were considerably lower (42·5 g). The PER of the treated protein was 2·27 (95% of that of casein) while that of the untreated protein was lower; only 1·63. In the case of the treated protein diet, 80% of food nitrogen was absorbed compared to 94% for casein and 65% for untreated protein, indicating improvement in protein digestibility with HCl treatment. The essential amino acid content of the treated kernel protein was comparable to egg protein. Available lysine content was higher in the treated sample than that of the untreated sample. © 1998 SCI.