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Functional and Nutritional Potential of Chickpea Protein Hydrolysates: A Systematic Review and Plant-protein Network Analysis.

Chickpea is a protein-rich legume increasingly explored as a substrate for functional plant-based ingredients. Chickpea protein hydrolysates (CPHs) and chickpea-derived peptides (CPs), obtained through enzymatic hydrolysis or simulated gastrointestinal digestion, may provide technological and biological properties while supporting the valorization of chickpea fractions and by-products. This review integrates a network analysis of title-abstract terms from 5,728 unique Scopus and PubMed records on plant protein hydrolysates with a systematic review of 72 studies focused on CPH production, peptide characterization, bioactivity, and translational gaps. The evidence indicates that CPHs and CPs show promising antioxidant, antihypertensive, antidiabetic, anti-inflammatory, lipid-lowering, immunomodulatory, antimicrobial, and anticancer-related activities, mainly supported by biochemical assays, cell models, and animal studies. However, heterogeneous hydrolysis protocols, incomplete peptide characterization, inconsistent bioactivity methods, limited scale-up evidence, and the absence of human intervention trials restrict translation. Future studies should prioritize standardized protocols, mechanistic validation, bioavailability, sensory and regulatory assessment, food-matrix validation, and clinical trials.

Cicer

Detection and possible origins of aminomalonic acid in protein hydrolysates.

Aminomalonic acid (Ama) was first detected in alkaline hydrolysates of proteins in 1984. In this work we describe our search for the origin of aminomalonic acid in alkaline hydrolysates of proteins. We have developed a technique for quantitation of aminomalonic acid based upon gas chromatography/mass spectrometry. Using this technique, we find approximately 0.3 Ama/1000 amino acids in hydrolysates of Escherichia coli protein. We have demonstrated that Ama is not formed from any of the 20 major amino acids during the hydrolysis procedure. Furthermore, the amount of Ama found does not depend on the presence of small amounts of O2 during the hydrolysis. Thus far, we have not been able to demonstrate an artifactual origin for Ama. The results described above suggest that Ama may indeed be a constituent of proteins before the hydrolysis procedure. Possible origins of Ama include errors in protein synthesis and oxidative damage to amino acid residues in proteins.

Amino Acid Sequence

Chlorohydrins in protein hydrolysates.

Four samples of neutral fractions of protein hydrolysates were separated by gas chromatography and the individual components were identified from the mass spectra obtained. Some of the identified compounds were not previously reported as volatile components of foodstuffs. Three of these compounds namely 3-chloropropan-1-ol, 2,3-dichloropropan-1-ol, and 1,3-dichloropropan-2-ol, were toxic chlorohydrins. 1,3-Dichloropropan-2-ol was present in samples in concentrations 0.17 to 0.94 mg/kg. To check the possibilities of the formation of these chlorohydrins and to find their precursor, glycerol, and hydrochloric acid mixtures were heated under conditions of producing protein hydrolysates. All three chlorohydrins, formerly found in protein hydrolysates have been identified.

Chlorohydrins

Sodium acetate as a preservative in protein hydrolysate solutions.

The inhibitory effect of sodium acetate on microorganism growth in protein hydrolysate solutions was studied. Solutions of 5% protein hydrolysate and 5% dextrose in water (seven parts) and 50% dextose in water (three parts) containing 0, 30, 50 and 90 mEq/liter of sodium acetate were inoculated with Staphylococcus aureus, Escherichia coli, Candida albicans and Pseudomonas aeruginosa. The number of colony-forming units in the solutions after inoculation was compared with that after incubation for 24 hours at 37 C. Sodium acetate inhibited growth of S aureus and E coli. Growth of P aeruginosa was inhibited in protein hydrolysate solutions with and without sodium acetate; inhibition could not be attributed solely to sodium acetate and may have been releated to pH of the solutions (4.7 to 5.4). Growth of C albicans was not inhibited by sodium acetate. Sodium acetate reduced growth of some common contaminants of protein hydrolysates. Sodium acetate is known to reduce metabolic acidosis, a reported complication of parenteral nutrient therapy and a possible predisposing factor in C albicans sepsis. Addition of sodium acetate to protein hydrolysate solutions should be considered seriously.

Acetates

Calcium and zinc retention from protein hydrolysate formulas in suckling rhesus monkeys.

OBJECTIVE: To determine calcium and zinc retention from infant formulas based on protein hydrolysates. DESIGN: Randomized, crossover. SETTING: Newborn nursery at the California Primate Research Center, Davis. PARTICIPANTS: Suckling infant rhesus monkeys (N = 7), aged 6 weeks at the beginning of the study. Each infant received seven different formulas. INTERVENTIONS: Fasted infant monkeys were fed diets radiolabeled with calcium 47 and zinc 65. Retention was determined by counting whole body radioactivity immediately after dosing and 7 days after dosing. MEASUREMENTS AND RESULTS: Retention of 47Ca was a mean (+/- SEM) of 79% +/- 4% from casein hydrolysate and 72% +/- 6% from the whey protein hydrolysate formula. Calcium 47 retention from hydrolysates based on whey protein/casein mixtures (a ratio of 60:40 or 50:50) was similar despite differences in protein sources and calcium content. Calcium 47 retention from two types of soy/collagen hydrolysate formula was found to be 68% +/- 6% and 59% +/- 4%, respectively, which is significantly lower than retention from casein hydrolysate. Considering the different calcium content of these formulas, total calcium retention from milk protein hydrolysates was higher than from soy/collagen products. Retention of 65Zn from milk protein hydrolysates ranged from 18% +/- 3% to 29% +/- 4% and was higher than that from soy/collagen formulas with a mean retention of 7% +/- 3% and 10% +/- 4%, respectively. Despite these differences in 65Zn retention, total zinc retention from all soy/collagen formulas was similar due to their higher zinc content. CONCLUSIONS: Calcium and zinc bioavailability was high from formulas based on milk protein hydrolysate, but was considerably lower from soy hydrolysates. Higher levels of calcium and zinc provided in soy hydrolysate formula compensated for the lower bioavailability and resulted in similar amounts of calcium and zinc retained.

Absorption

[The immunogenicity and allergenicity of an experimental cow's milk protein hydrolysate].

Recently hydrolyzed cow milk proteins have been introduced for the production of infant formulas and are available as hypoallergenic infant formulas. To achieve a decrease in antigenicity and allergenicity a protein hydrolysis (mostly enzymatic) is performed. Sera of different groups were tested for IgG and IgE antibody-binding: 31 controls, 36 atopic children, and 20 children with cow milk protein allergy. Histamine release from basophil leucocytes after incubation with the cow milk proteins beta-lactoglobuline and casein, as with the cow milk protein hydrolysate, was determined additionally for five control, 10 atopic, and five cow milk allergic children. IgG binding to cow milk protein and to the hydrolysate was found in the majority of the sera tested. IgE binding was detectable in sera of only five of the 10 cow milk allergic children, despite detection of specific IgE-antibodies against cow milk proteins in all sera. Histamine release by the cow milk hydrolysate was observed for five atopic and two cow milk allergic children. The cow milk hydrolysate demonstrated a decreased but partially conserved antigenic/allergenic potency compared with cow milk proteins.

Adolescent

Four new methods of debittering protein hydrolysates and a fraction of hydrolysates with high content of essential amino acids.

Extraction of enzymatic protein hydrolysates with azeotropic secondary butyl alcohol (SBA) or aqueous ethanol (AE) or aqueous isopropranol (AI), seems to be an efficient and generally applicable method for removal of bitter compounds. The bitter peptides are concentrated in the alcohol-phase which has an extremely bitter taste. It has a concentration of 40-70 p. 100 essential amino-acids. In the alcohol-phase leucine, isoleucine, phenylalamine and tryptophan were particularly increased. Experiments showed that the bitterness of the alcohol-soluble fraction could be reduced by applying the plastein reaction. A reduction in bitterness of protein hydrolysates could also be achieved by applying hydrophobic interaction chromatography. Of tested gels, hexyl-sepharose was found to be the most effective for debittering of protein hydrolysates.

Amino Acids

[Effect of parenterally administered protein hydrolysates on the secretory function of the small intestine].

The effect of intravenous infusion of proteinic hydrolysates on the secretory function of the intestines was studied in dogs with an intestinal loop isolated starting from the initial portion of the jejunum. The preparation of proteinic hydrolysates, such as the caseine hydrolysate TSOLIPK, aminopeptide and hydrolysine L-103 with their drop-by-drop infusion into the posterior vena cava to dogs on an empty stomach were found to have in most cases an effect on the periodicity of the small intestine secretory activity. The infusion of proteinic hydrolyastes failed to exert any essential influence on the secretion of the dense proportion of the juice, whereas the secretion of the liquid component of the intestinal juice increased in all experiments involving introduction of all the proteinic hydrolysates. The concentration of the total protein in the liquid part of the intestinal juice with intravenous infusion of the preparations remained unchanged. At the same time, the amount of protein secreted together with the intestinal juice at the rate of single secretory action was in the instance of the caseine hydrolysate TSOLIPK and aminopeptide infusion proved 1 1/2--3 times as great as in the tests without infusion.

Animals

Influence of dosage regimen on responses of the arcuate nucleus to subcutaneous injection of a protein hydrolysate.

The effect of administration of a glutamate-containing protein hydrolysate on the arcuate nucleus of 10-day-old mice was studied by two methods. Arcuate nucleus damage resulted when administration was by a single large subcutaneous dose (100 ml/kg). When the same total dose was administered subcutaneously in five small doses (20 ml/kg) over a period of 8 h, the damage to the arcuate nucleus did not occur. The latter method of administration was to simulate a clinical infusion. The results demonstrate that there is no hazard to the arcuate nucleus w-en glutamate-containing protein hydrolysates are administered by infusion.

Animals

Chemical and immunological properties of a protein hydrolysate formula.

Clinical observation suggested that a protein hydrolysate formula designed to serve as an oral elemental diet was capable of producing untoward reactions in some children with malabsorption syndromes caused by cow milk protein allergy. An immunological study of the antigenicity of this hydrolysate was undertaken. Although it is claimed that the hydrolysate is produced from casein, it was shown that it produced, after injection into animals, precipitating antibodies against at least three of the whey proteins. Analysis of the molecular weight of this hydrolysate showed it to contain a polypeptide fraction with molecular weight above 3,850.

Animals

Immunogenicity evaluation of protein hydrolysates for hypoallergenic infant formulae.

Casein and soy protein were enzymatically hydrolyzed for potential use in a hypoallergenic infant formula. To assess the relative immunoreactivity of the hydrolysates, rabbits were immunized with either the intact proteins or the protein hydrolysates using a vigorous immunization protocol. Serum samples were tested using ELISA methods that quantitated IgG antibody specific for the immunizing protein hydrolysates and the corresponding intact proteins. The results showed that the protein hydrolysates had substantially lower immunogenicity than the parent proteins. Also, antibody specific for the parent protein showed very low cross-reactivity with the hydrolysates. Both of the protein hydrolysates seem to be promising candidates for use in hypoallergenic infant feeding systems.

Animals

A method for measuring hydroxylysine and glycosylated hydroxylysines in urine and protein hydrolysates.

A method for measuring hydroxylysine and glycosylated hydroxylysines is described, based on the separation of the 3 compounds by ion-exchange chromatography, followed by spectrophotometric analysis of the hydroxylysine present as glucosylgalactosylhydroxylysine, galactosylhydroxylysine and free hydroxylysine. The method does not require prior preparation of the urine sample nor the use of high-resolution ion-exchange systems. The method is applicable to the determination of the glycosylated hydroxylysine and hydroxylysine content of urine or alkaline hydrolysates of proteins.

Chromatography, Ion Exchange

Determination of 3-methylhistidine in hydrolysed proteins by fluorescamine derivatization and high-performance liquid chromatography.

A method is described for the determination of the 3-methylhistidine content in myofibrilar proteins (myosin and actin) using reversed-phase high-performance liquid chromatography with ultraviolet detection. Proteins were hydrolysed and free amino acids were derivatized with fluorescamine. Elution was performed isocratically with acetonitrile-water (24:76). This method allows the detection of picomole amounts of 3-methylhistidine in myosin and actin.

Animals

[Serum lipids in experimental atherosclerosis in guinea pigs treated with protein hydrolysate].

The authors carried out studies on 223 male guinea pigs, weighting from 350 to 500 gm, fed with a diet containing 0,3% of cholesterol, disolved in cow butter. A part of the animals were injected with protein hydrolysate every other day for a period of 140 days. The level of serum lipids-total cholesterol, beta-lipoproteins, phospholipids and total lipids was examined. They found significantly higher values in the animals, receiving cholesterol in comparison with the control animals-292.4:84.9; 139.4:59.3; 457.1:241.2; 105.5:62.0 respectively for, beta-lipoproteins, total cholesterol, total lipids and phospholipids. The administration of protein hydrolysate in a dose of 0,5 ml/100 gm of body weight affected favourably fat metabolism. The increase of serum fat-lipid components was less manifested in comparison with the nontreated atherosclerotic animals. The greatest difference was found in beta-lipoproteins (292.4:143.8) and total, lipids (457.1:300.8). Statistically significant difference was established in total cholesterol as well. (139.4:81.9). There was an impression that this effect was due to the protective action of aminoacids of the protein hydrolysate on the normal functions of liver and the favourable effect on the tunover of the administered cholesterol.

Animals

Long-term prevention of allergic diseases by using protein hydrolysate formula in at-risk infants.

This prospective, long-term study assessed the effects of a protein hydrolysate formula on allergy prevention in infants with a family history of allergy. Infants were randomly assigned to receive either the hydrolysate formula (n = 92) or an adapted cow milk formula (n = 85) alone or with breast-feeding for 4 months. The groups did not differ in family allergy history scores or cord blood IgE levels. After 4 months, total IgE levels and allergic reactions did not differ significantly between groups, although the hydrolysate group had a lower prevalence of eczema. At 12 months of age, neither IgE levels nor allergic reactions were significantly different. At 2 years of age, however, 18 allergic reactions had occurred in the hydrolysate group and 31 had occurred in the control group; the differences were significant for eczema (p < 0.001) but not for asthma. At 4 years of age, allergic signs were found in 11 children in the hydrolysate group and in 17 children in the control group; the difference was significant only for eczema (p < 0.01). These results suggest that early feeding of a protein hydrolysate formula to infants at risk for allergies had a long-term preventive effect on the prevalence of eczema but not of asthma.

Body Height

[Changes in the perfusion of the internal organs of rabbits with experimental atherosclerosis treated with a protein hydrolysate].

The authors examined the vascularization of the internal organs of rabbits with experimental atherosclerosis, induced by the method of Sapirstein with 86-Rubidium. The experiments were carried out on male rabbits of the strain Cincilla, fed with cholesterol in a dose of 0.2 gm/kg of body weight daily for a period of 90 days. Part of the animals were treated with protein hydrolysate in a dose of 5 ml/kg of body weight subcutaneously, but the remaining part of the animals-with saline. There was a reduced vascularization in heart, kidney, intestine, liver, adrenals, pancreas, and other internal organs in rabbits fed with cholesterol and treated with saline. Administration of protein hydrolysate had protective effect on the vascularization of the organs accumulation of 86-Rubidium in a large part of the animals presented values higher than rhose of the control group. The authors suggested that under the influence of amino-acids from the protein hydrolysate the state of the endothelial cells was stabilized and the local, feactions of vascularization were stimulated as well.

Animals

Treatment of children with phenylketonuria using a phenylalanine-free protein hydrolysate (Albumaid XP).

Albumaid XP, a phenylalanine-free protein hydrolysate, was used for treatment of five phenylketonuric infants born between January, 1970, and September, 1972. The results were compared with those obtained from the five infants most recently treated with Lofenalac in our clinic prior to 1970. Treatment was begun by 2 months of age in all instances. Satisfactory physical growth and mental development were achieved using either Albumaid XP or Lofenalac, and there were no major differences in the outcomes with either treatment. The two protein sources may be used interchangeably for treatment of phenylketonuria.

Amino Acids

[The mechanism of action of parenterally administered protein hydrolysates on the exocrine activity of the pancreas].

In dogs with fistulae of the stomach and the pancreatic duct as well as in dogs with artificially made partition between the stomach and the duodenum, effect of protein hydrolysates administered into the blood, on the pancreas secretion, was shown to manifest itself only in conditions of unopposed transition of the stomach acid contents into the duodenum. In the mechanism of protein hydrolysates action on the pancreas secretion, the major part is played by their ability to stimulate the stomach secretion and the transition of the acid content into the duodenum. Under the influence of the acid contents, release of the secretin occurs in the duodenum which induces the secretion of the pancreatic juice.

Amylases