Fish meals, fish components, and fish protein hydrolysates as potential ingredients in pet foods. (65/260)

An experiment to determine the chemical composition and protein quality of 13 fish substrates (pollock by-products, n = 5; fish protein hydrolysates, n = 5; and fish meals, n = 3) was conducted. Two of these substrates, salmon protein hydrolysate (SPH) and salmon meal with crushed bones (SMB), were used to determine their palatability as components of dog diets. Pollock by-products differed in concentrations of CP, crude fat, and total AA by 71, 79, and 71%, respectively, and GE by 4.1 kcal/g. Fish protein hydrolysates and fish meals were less variable (approximately 18, 14, and 17%, and 1.4 kcal/g, respectively). Biogenic amine concentrations were much higher in fish protein hydrolysates as compared with pollock by-products and fish meals. Pollock liver and viscera had the highest total fatty acid concentrations; however, red salmon hydrolysate and SMB had the highest total PUFA concentrations (49.63 and 48.60 mg/g, respectively). Salmon protein hydrolysate had the highest protein solubility in 0.2% KOH. Based on calculations using immobilized digestive enzyme assay values, lysine digestibility of fish meal substrates was comparable to in vivo cecectomized rooster assay values and averaged approximately 90.3%. Also, pollock milt, pollock viscera, red salmon hydrolysate, and sole hydrolysate had comparable values as assessed by immobilized digestive enzyme assay and rooster assays. A chick protein efficiency ratio (PER) assay compared SMB and SPH to a whole egg meal control and showed that SMB had high protein quality (PER = 3.5), whereas SPH had poor protein quality (PER value less than 1.5). However, using whole egg meal as the reference protein, both fish substrates were found to be good protein sources with an essential AA index of 1.0 and 0.9 for SMB and SPH, respectively. In the dog palatability experiments, a chicken-based control diet and 2 diets containing 10% of either SPH or SMB were tested. Dogs consumed more of the SPH diet compared with the control, and similar amounts of the SMB and control diets. The intake ratios for each were 0.73 and 0.52, respectively. Salmon protein hydrolysate was especially palatable to dogs. These data suggest that chemical composition and nutritional quality of fish substrates differ greatly and are affected by the specific part of the fish used to prepare fish meals and fish protein hydrolysates.  (+info)

Meat hydrolysate and essential amino acid-induced glucagon-like peptide-1 secretion, in the human NCI-H716 enteroendocrine cell line, is regulated by extracellular signal-regulated kinase1/2 and p38 mitogen-activated protein kinases. (66/260)

Glucagon-like peptide-1 (GLP-1) is a potent insulin secretagogue released from L-cells in the intestine. Meat hydrolysate (MH) is a powerful activator of GLP-1 secretion in the human enteroendocrine NCI-H716 cell line, but the mechanisms involved in nutrient-stimulated GLP-1 secretion are poorly understood. The objective of this study was to characterize the intracellular signalling pathways regulating MH- and amino acid-induced GLP-1 secretion. Individually, the pharmacological inhibitors, SB203580 (inhibitor of p38 mitogen-activated protein kinase (MAPK)), wortmannin (inhibitor of phosphatidyl inositol 3-kinase) and U0126 (inhibitor of mitogen activated or extracellular signal-regulated protein kinase (MEK1/2) upstream of extracellular signal-regulated kinase (ERK)1/2) all inhibited MH-induced GLP-1 secretion. Further examination of the MAPK pathway showed that MH increased the phosphorylation of ERK1/2, but not p38 or c-Jun N-terminal kinase over 2-15 min. Incubation with SB203580 resulted in a decrease in phosphorylated p38 MAPK and a concomitant increase in the phosphorylation of ERK1/2. Phosphorylation of ERK1/2 was augmented by co-incubation of MH with SB203580. Inhibitors of protein kinase A and protein kinase C did not inhibit MH-induced GLP-1 secretion. In contrast to non-essential amino acids, essential amino acids (EAAs) increased GLP-1 secretion and similar to MH, activated ERK1/2. However, they also activated p38-suggesting type of protein may affect GLP-1 secretion. In conclusion, there appears to be a crosstalk between p38 and ERK1/2 MAPK in the human enteroendocrine cell with the activation of ERK1/2 common to both MH and EAA. Understanding the cellular pathways involved in nutrient-stimulated GLP-1 secretion has important implications for the design of new treatments aimed at increasing endogenous GLP-1 release in type-2 diabetes and obesity.  (+info)

Dietary whey protein hydrolysate suppresses development of atopic dermatitis-like skin lesions induced by mite antigen in NC/Nga mice. (67/260)

BACKGROUND: Oral administration of enzymatic hydrolysate of cow's milk whey protein (WPH) has been reported to produce an anti-inflammatory effect. Since inflammation plays a role in dermatitis of allergic disease, we examined the influence of WPH on the development of atopic dermatitis (AD)-like skin lesions, induced in NC/Nga mice by the mite antigen Dermatophagoides pteronyssinus (Dp). METHODS: AD-like skin lesions were induced on the pinnae and backs of NC/Nga mice by daily application of Dp for 4 weeks. Mice were fed cow's milk casein (control), WPH or casein protein hydrolysate (CPH) diets for 2 weeks prior to Dp application. Clinical skin conditions were evaluated periodically by a clinical severity score, total serum IgE and soluble E-selectin levels were measured by enzyme linked immunosorbent assay (ELISA). RESULTS: WPH-fed mice showed significantly less AD-like skin lesions than those fed casein diets at 2 and 4 weeks after Dp application. In contrast, CPH-fed mice had manifestations in a similar manner as casein-fed mice did, and did not show an inhibitory effect. Serum soluble E-selectin levels, known as a marker of disease activity in AD patients, were significantly lower in the WPH diet group. CONCLUSIONS: Our results suggest that in addition to its hypoallergenicity an anti-inflammatory function, dietary WPH might be useful for reducing the severity of AD-like skin lesions.  (+info)

Palatability of hydrolysates and Other substitution formulas for cow's milk-allergic children: a comparative study of taste, smell, and texture evaluated by healthy volunteers. (68/260)

BACKGROUND: Hydrolyzed formulas used to feed infants with cow's milk-allergy can be classified as soy based, extensively hydrolyzed (casein, whey and mixed), and amino-acid based. Their unsatisfactory taste is reported by parents and physicians. OBJECTIVE: The aim of this study was to ascertain the palatability of these formulas in a double-blind taste test. MATERIALS AND METHODS: Fifty healthy volunteers performed a randomized-order double-blind test with 12 different milks. The taste, smell, smell, and texture of each formula were evaluated o n scales ranging from 1 (worst) t o 5 (best). The Pearson correlation coefficient between the peptide weight of each formula and the score obtained for each evaluated attribute was calculated. RESULTS: The soy formulas and rice formula had the best taste scores, followed by the whey hydrolysates; the mixed hydrolysates and the casein hydrolysates had the lowest taste scores. Individually the most palatable formula was mixed hydrolysate 1, by total score. We found a statistically significant correlation between peptide weight, reflecting the degree of hydrolysis of each formula, and the scores obtained for taste, texture, and overall palatability. CONCLUSION: The palatability of formulas is determined by the amount of bitter peptides obtained through hydrolysis. Flavorings and sweeteners may also contribute to palatability. Further studies are needed in order to determine how to modify the organoleptic properties of these products with the purpose of improving their palatability.  (+info)

Temperature-induced post-translational over-modification of type I procollagen. Effects of over-modification of the protein on the rate of cleavage by procollagen N-proteinase and on self-assembly of collagen into fibrils. (69/260)

Previous observations suggested that incubating fibroblasts at elevated temperature caused over-modification of type I procollagen by post-translational enzymes because of a delay in folding of the collagen triple helix. Here, human skin fibroblasts were incubated at 40.5 instead of 37 degrees C, and the type I procollagen secreted into the medium was isolated. Analysis of the protein indicated that there was an increase of about 5 residues of hydroxylysine/alpha chain and about 1 residue of glycosylated hydroxylysine/alpha chain. Assays with procollagen N-proteinase indicated that the N-propeptide of the over-modified collagen was cleaved at a decreased rate, apparently because the over-modification altered the conformation-dependent cleavage site for the enzyme. Assays in a system for assembly of collagen into fibrils demonstrated that the over-modified protein had a higher critical concentration for self-assembly. Also, the fibrils formed from the over-modified collagen at 31 and 29 degrees C had smaller diameters than fibrils formed from normal type I collagen. The results provide direct evidence for earlier suggestions that post-translational over-modification of a fibrillar collagen can alter the morphology of the fibrils formed. The results also indicate that some of the biological consequences of the mutations in type I procollagen causing heritable disorders must be ascribed to the effects of post-translational over-modifications that frequently occur as secondary consequences of changes in the primary structure of the protein.  (+info)

Antioxidative activity of hen egg ovalbumin hydrolysates. (70/260)

To evaluate the antioxidative activity of the hydrolysates of ovalbumin, the antioxidative activities of the enzymatic extracts were evaluated using three different methodologies scavenging assays such as superoxide anion, hydroxyl radical, and inhibitory oxidation of linoleic acid in vitro, and the activities of SOD, GSH-PX, CAT and the level of MDA were determined in serum and liver of aged mice induced by G-gal. The results showed that the hydrolysates had a distinctly inhibitory action to superoxide anion made by alkaline pyrogallic acid, HO. produced by Fenton reaction, the oxidation of linoleic acid in linoleic acid autoxidation system, and presented a positive correlation. The inhibition capacity of hydrolysates against superoxide anion and HO. were more than 45% and 56% respectively at the concentration 5 mg/mL. And the hydrolysates could significantly (p< 0.01) prevented the activities of SOD, GSH-Px, and CAT against reducing and all three concentrations could significantly (p< 0.01) decrease the MDA contents in the serum and liver of aged mice induced by G-gal. The antioxidative activity of high concentration was similar to that of control group.  (+info)

Antihypertensive effect of rice protein hydrolysate with in vitro angiotensin I-converting enzyme inhibitory activity in spontaneously hypertensive rats. (71/260)

Angiotensin I-converting enzyme (ACE) plays a crucial role in the regulation of blood pressure as well as cardiovascular function. ACE catalyzes the conversion of angiotensin I to vasoconstrictor angiotensin II, and also inactivates the antihypertensive vasodilator bradykinin. Inhibition of ACE mainly results an overall antihypertensive effect. Food protein-derived peptides can have ACE-inhibiting properties and thus may be used as a novel functional food for preventing hypertension as well as for therapeutic purposes. In the present study, rice protein was hydrolyzed by protease Alcalase for 2 h and the resulted hydrolysate was determined for ACE inhibitory activity in vitro. The antihypertensive effect of rice protein hydrolysate was also investigated in spontaneously hypertensive rats (SHR). The Alcalase-generated hydrolysate showed strong in vitro ACE inhibitory activity with the IC50 value of 0.14 mg/ml. A significant decrease in systolic blood pressure in spontaneously hypertensive rats was observed following single oral administration of this hydrolysate at a dose of 600 mg/kg of body weight. A potent ACE inhibitory peptide with the amino acid sequence of Thr-Gln-Val-Tyr (IC50, 18.2 microM) was isolated and identified from the hydrolysate. Single oral administration of Thr-Gln-Val-Tyr at a dose of 30 mg/kg of body weight also significantly decreased blood pressure in SHR. These results suggest that in vitro ACE inhibitory activity and in vivo antihypertensive activity could be generated from rice protein by enzymatic hydrolysis. The rice protein hydrolysate prepared with Alcalase might be utilized to develop physiologically functional food with antihypertensive activity.  (+info)

Effect of angiotensin I-converting enzyme inhibitory peptide from rice dregs protein on antihypertensive activity in spontaneously hypertensive rats. (72/260)

BACKGROUND: Angiotensin I-converting enzyme (ACE) inhibitory peptide has good effect on blood pressure regulation. Therefore, research to find and develop safer, effective and economical ACE inhibitors is necessary for the prevention and remedy of hypertension. So food-derived ACE inhibitory peptides isolated from food or from enzymatic digestion of food proteins are the safe and efficient substitution for human health. OBJECTIVE: To investigate the effect of rice dreg enzymatic hydrolysates as an anti-hypertensive in vivo with spontaneous hypertension rats (SHRs). DESIGN: The once-oral administration experiments with rice dreg hydrolysates peptide (RDHP) in different doses were conducted using 6 weeks old spontaneous hypertension rats as the test model. Twenty five SHRs were randomized into five groups according to blood-pressure level. The group A is blank control group, the group B positive control group (Captopril), the group C (1.0 mg/kg), the group D (RDHP 10 mg/kg) and group E (RDHP 50 mg/kg). The administration approach is to fill in stomach by mouth. The blood pressure value was observed for each group. The long term oral administration design was conducted for one month. Twenty four SHRs were randomized into 3 groups. The first group is the blank control, the second group is low dose (RDHP 10 mg/kg) and the third group is high dose (RDHP 20 mg/kg). In administration period, blood pressure was measured for once a week. OUTCOMES: The once-oral administration animal experiments showed that the blood pressure of SHR drop was 11 mmHg, 17 mmHg, 26.00 mmHg, 17 mmHg at a dosage of 1 mg/kg, 10 mg/kg, 50 mg/kg hydrolysates and 1 mg/kg captopril, respectively, after 1h administration. The results of long-term oral administration indicated that the blood pressure drop was 17 mmHg, 26 mmHg in 10 mg/kg and 20 mg/kg, respectively after 30 days administration. RDHP not only promoted the growth of SHR, but also had no adverse effect on heart rate. CONCLUSIONS: The present study indicated the inhibitory peptides from rice dreg hydrolysate had significant antihypertensive action and no other side effects by oral administration in SHR.  (+info)