PRODUCTION AND USES OF PROTEIN HYDROLYSATES AN REMOVAL OF BITTERING PRINCIPL

PRODUCTION AND USES OF PROTEIN HYDROLYSATES AN REMOVAL OF BITTERING PRINCIPL

CHAPTER ONE

INTRODUCTION

Protein hydrolysate can be defined as the end product of protein hydrolysis using chemical and enzymatic methods.

Protein hydrolysate is used in a variety of specialty foods, including nonallergenic infant formula, diet foods, and other special nutritional foods.

Many hydrolysates, such as Soya or Casein hydrolysates, have a bitter taste after being hydrolyzed into small peptides with protease enzymes.

Protein maldigestion, which is frequently associated with cystic fibrosis and milk protein allergy, can be overcome by replacing intact proteins in the diet with synthetic amino acid mixtures or enzymic protein hydrolysates. Hydrolysates may be the preferred treatment for two reasons. Protein hydrolysates’ amino acids and small peptides have been shown to be more bioactive.

Protein hydrolysates are more easily ascribed from the small intestine than their equivelent pure amino acid mixture; additionally, protein hydrolysates are significantly less expensive than synthetic amino acid mixtures. Nonetheless, protein hydrolysates have a significant drawback in the form of a bitter taste that develops during the enzymatic hydrolysis process.

Murray r (1952) demonstrated that treating enzymic casein hydrolysates with activated carbon improved the taste of preparations significantly. However, due to the simultaneous loss of a large proportion of the hyptophan during treatment, authors regarded this method of improving taste as impractical. A novel approach was presented in two recent studies, in which a casein hydrolysate with a low bitter taste was obtained by sequentially employing

Papa in and of pig kidney homogenate, the latter serving as an exopeptidase source. However, prolonged hydrolysis times were required, necessitating the use of dolor form to control bacterial growth.

Protein that has been solubilized by enzymatic hydrolysis has a wide range of food and biomedical applications. Their improved solubility, heat stability, and resistance to precipitation in acidic environments, where many proteins are insoluble, appeal to biochemists and nutritionists involved in the research and development of high protein food formulations.

These valuable protein supplements may have applications in the diets of people with digestive disorders, pre and post operative abdominal surgical patients, geriatric and convalescent feeding, and others who do not eat for a variety of reasons.

a healthy diet. Unfortunately, the use of enzyme-treated hydrolysates in dietary food applications has been limited in many cases due to the presence of bitter flovour. The bitter peptides and amino acids liberated during the hydrolytic process are primarily responsible for the unpalatability of these hydrolysates. Bitterness appeasement appears to be closely related to the peptides’ content and sequence of hydrophobic amino acids.

Bitterness was reduced by further hydrolysis of pepsin digested soy protein with bacterial proteins or an exopeptidase. Protein hydrolysates are also chemotropically plastered. Similarly, Clegg and Mc Millan (1974) reported that a combination enzyme treatment of casein for 18 hours followed by the addition of a homogenate of swine kidney cortex produced a similar result.

Hydrolysate with less bitterness.

Another approach to addressing the bitter flavor issue appeared to be attempting to improve the flavor of protein hydrolysates by reducing the hydrophobic peptide and amino acid content of the digests. Many years ago, it was discovered that activated carbon could absorb the aromatic amino acids tryptophan, tyrosine, and phenycalaline. Murrgy and Baker used carbon to treat a commercial enzymic hydrolysate of casein and reported that the taste was significantly improved. The carbon was eluted with a bitter tasting polypeptide fraction.

Commercially available phenol-formaldehyde resins with carbon-like structures are used in a wide range of ion-exchange and absorbent applications. As a result, the ability of a phenol-fomaldeliyde resin polymer to preferentially interact with the monoplane

The presence of groups in hydrophobic peptides was determined, and a hydrophobic chromatography process for debittering protein hydrolysates was developed as a result of the findings.

The difficulty in preventing the formation of bitter peptides or removing them from the hydrolysate has been well documented in the preparation of soluble hydrolysate from protein such as casein. Among the numerous casein hydrolysate studies, the process developed by Clegg and Mc Millan (1974) using skim milk as a substrate should be mentioned. When skim milk protein is hydrolyzed with papain, a bitter testing hydrolysate is formed, which is then blandened by hydrolysis with exopeptidase from pig kidney tissue. Unfortunately, the procedure is both time-consuming and expensive. Another expensive debittering method is hydrophobic chromatography of enzymatic protein hydrolysate.

on hexylsepharose. An extraction method that uses azeotropic secondary butyl alcohol to completely remove bitter compounds.

A comparison of adsorption methods of debittering pronase- and ficinhydrolyzed skim milks was made during a study aimed at producing bland, soluble skim milk hydrolysate at a reasonable cost without a significant loss of nutritional value. The comparison and partial identification of bitter peptides formed in skim milk hydrolysates are reported. Because of the minimal changes in taste and appearance provided by the addition of this treated skim milk to soft drinks or fruit juices, the resulting beverages are expected to look and taste like the original beverages while retaining nearly all of the nutritional value of skim milk.

It is well known that bitterness can be produced in sake and other fermented products, detracting from their quality. Bitter peptides and their derivatives formed during the ageing process of these fermented products cause this bitterness. Enzymatic hydrolysis of protein frequently produces bitter peptides, lowering the value of the products.

Since bitter peptides are known to be produced by enzymatic hydrolysis, several attempts have been made to reduce bitter peptide production during the enzymatic hydrolysis process by changing the enzymes and or reaction conditions.

Of course, amino acids are present in skim milk, soybean casein, whey protein concentrate (NPC), and casein hydrolysate. Because protein and peptides needed a debittering method for bitter peptides,  could block the bitterness. Creaming powder, vegetable oil, and margarine are fat-like substances that can block hydrophobic groups of bitter peptides and thus reduce bitterness. Some acidic amino acids were added to the study to confirm their ability to mask bitterness, with Asp, Glu, and Tau being used. Taurine (Tau) is not an acidic amin acid, but it has a very acidic function. Taurine, like other acidic amino acids or peptides, was expected to reduce bitterness.