Henryk Kostyra

Determination of α-amino nitrogen in pea protein hydrolysates : a comparison of three analytical methods

Abstract Three spectrophotometric methods, using 2,4,6-trinitrobenzenesulphonic acid (TNBS), o-phthaldialdehyde (OPA) or ninhydrin, for the determination of α-amino nitrogen in pea protein isolates and hydrolysates were compared. The determined amounts of α-amino nitrogen differed greatly, depending on the method used. The TNBS and OPA methods produced comparable results, whereas the data obtained with the ninhydrin method were only half of the TNBS or OPA values. Colour stability, recovery of the standard from the protein matrix and reproducibility of the results were determined. The methods showed good accuracy (SE 1–3%) with recovery values of the standard ( l -leucine) from the protein matrix of 91, 111 and 75% for the OPA, ninhydrin and TNBS method, respectively.

Impact of Maillard Reaction on Immunoreactivity and Allergenicity of the Hazelnut Allergen Cor a 11

Few studies exist on the influence of processing methods on structural changes and allergenic potential of hazelnut proteins. This study focused on the effect of glycation (Maillard reaction) on the immunoreactivity and degranulation capacity of the purified hazelnut 7S globulin, Cor a 11. After heating, the extent of the Maillard reaction, sensitivity to proteolysis, binding of human IgE or rabbit IgG, and degranulation capacity were analyzed. Changes in electrophoretic mobility, amount of free amino groups, and contents of bound sugar and fructosamine indicated that glycation of Cor a 11 occurred at all conditions. Glycation at 37 °C did not influence the specific IgG or IgE binding and was decreased after heating at 60 and 145 °C. Heating, with or without glucose, at 145 °C increased basophil degranulation capacity. The results suggest that glycation of Cor a 11 at 60 and 145 °C may decrease the IgE/IgG binding properties but not the degranulation capacity of basophils. This is possibly related to aggregation of the proteins as a result of the Maillard reaction.

Transport of μ-opioid receptor agonists and antagonist peptides across Caco-2 monolayer

Milk is the source of beta-casomorphins--biologically active peptides with opioid activity--which are suspected to play various roles in the human body. The local influence of exogenous opioid peptides on gastrointestinal functions has been widely reported. After passing the gut barrier, beta-casomorphins may affect the functions of immunological system, as well as dopaminergic, serotoninergic and GABA-ergic systems in brain, regulate the opioid receptor development and elicit behavioral effects. However, possibilities and mechanisms of the intestinal transport of beta-casomorphins in human body in vivo have not been reported so far. In our research, the transepithelial transport of micro-opioid receptor agonists--human beta-casomorphin-5 and 7(BCM5, BCM7) and antagonist--lactoferroxin A (LCF A) have been investigated using Caco-2 monolayer. In order to determine the pathway of investigated peptide transport across Caco-2 monolayer, two directions of the transport (apical to basolateral and basolateral to apical) have been studied. All investigated peptides were transported across the human intestinal cell line Caco-2 and the curves of cumulative amount of transported peptides in time were linear in each case. In addition, the hydrolysis of beta-casomorphins during 60 min of experiment by dipeptidyl peptidase IV was observed. The data suggest the possibility of transport of opioid peptides derived from food across human intestinal mucosa.

β-Casomorphin-7 isolated from Brie cheese

Peptide extract from Brie cheese was examined. The opioid peptide was isolated from the extract. Its amino acid composition and N- and C-terminal amino acids were determined. Based on these analyses, the isolated peptide was assumed to correspond to β-casomorphin-7 (Tyr-Pro-Phe-Pro-Gly-Pro-IIe). The opioid activity was measured by examining the effects of peptide extract and isolated opioid peptide on the motor activity of isolated rabbit intestine. © 1999 Society of Chemical Industry

Changes of β-casomorphin content in human milk during lactation

Milk is the best, complete food important for the development and nourishment of a neonate. Except for nutrients, milk contains biologically active opioid peptides derived from beta-casein, named beta-casomorphins (BCMs), which can exert effects in the gastrointestinal tract as well as in the whole body of neonates. The content of beta-casomorphins in human milk during maturation phases has not been studied so far. The aim of this study was to determine the content of beta-casomorphin-5 and -7 in human milk in different phases of lactation. A significantly higher concentration of both beta-casomorphins was found in colostrum than in mature milk. The concentration of beta-casomorphin in milk collected in the second month of lactation was similar to the level obtained in the fourth month of lactation. The content of beta-casomorphins in human milk was observed with the period of lactation. The level of opioid peptides may depend on the function of these peptides in neonates body and may be associated with the maturation process.

Milk from cows of different β-casein genotypes as a source of β-casomorphin-7.

The aim of this study was to quantify β-casomorphin-7 in raw, hydrolyzed and processed milk in different stages of the cow lactation. The obtained results lead to the following conclusion: the highest amount of β-casomorphin-7 released from the hydrolyzed and processed milk is related to the β-casein A1 allele, irrespective of a lactation period. Some traces of β-casomorphin-7 in milk from cows with the β-casein A2 variant are probably a result of the acid hydrolysis of β-casein during its digestion with pepsin. It has been shown that processing of raw milk at high temperatures affects, in a slight degree, the differences between β-casomorphins-7 originating from different β-casein genotypes. The obtained results suggest a possibility to provide a new nutritional factor for milk quality based on the content of β-casomorphin-7 liberated in vivo from milk digested by a mixture of the gastrointestinal enzymes.

The impact of pea protein hydrolysates on bacterial physiological activity—An in vitro study

So far, food proteins have been perceived hitherto purely as a source of nutrients indispensable for maintaining life. However, latest findings strongly indicate that food proteins may release biologically active peptides in a consequence of enzymatic degradation. Such hydrolysates may be used as food components in order to beneficially influence human health. Additionally, such modified peptides may affect the balance of bacteria inhabiting human gastrointestinal tract and thus bring about health complication of the host. Although pea seeds are of significant nutritional value due to their high contents of proteins, carbohydrates and fibre, they are also responsible for health inconveniences resulting from their susceptibility to digestion and occurrence of antinutritional as well as allergic compounds. The enzymatic degradation may pass over these nutritional obstacles by liberating hydrolysates empowered not only to exert their impact on the human physiology but also on bacterial intestinal ecosystem. Therefore, the aim of this study was to evaluate the influence of pea protein hydrolysates on bacteria typical for the small intestine. Pea protein hydrolysates have proved to diversely modulate physiological activity of bacteria existing in different states. The observed detrimental effect on planktonic bacteria was abolished in the case of bacteria immobilized to the solid surfaces, confirming the protective effect of biofilms. Additionally, Lactobacilli displayed adaptive properties enabling them to utilize pea protein hydrolysates regardless their state of existence.

Content of β-casomorphins in milk of women with a history of allergy

The prevalence of food allergies increased over the past decade. Most symptoms of food allergy appear during the first 2 yr of life. The aim of this study was to determine the β‐casomorphin‐5 and ‐7 (BCMs) in colostrum and milk of 12 breast‐feeding women with a history and clinical manifestation of food allergy. The results were compared with the data obtained from a control group of healthy age‐matched breast‐feeding women. The level of BCM in women with food allergy was constant during lactation, whereas the highest level of opioid peptides was found in colostrums of healthy women with a subsequent rapid decrease in mature milk. These differences in BCMs profile between allergic and healthy breast‐feeding women suggest that BCM content in the human milk may be an indicator of allergic conditions.

Impact of glycated pea proteins on the activity of free-swimming and immobilised bacteria.

BACKGROUND Glycation (non-enzymatic glycosylation), a spontaneously occurring process, is responsible for alteration of the structures and biological activities of proteins, making them highly active. Regrettably, information regarding the impact of glycated food proteins on intestinal bacteria still remains sparse. Pea seeds are considered to be a biological material of a high nutritional value, low content of anti-nutritional substances and proven health-promoting action and therefore they were used in this study. Since glycated pea proteins are proven to display a lowered susceptibility to the enzymatic digestion, their impact on the activity of both free-swimming and immobilised bacteria was studied. RESULTS In vitro model systems were used to prove the stimulatory impact of glycated pea proteins on the proliferation rate and survival, as well as on the metabolic activity of free-swimming and immobilised bacteria. CONCLUSIONS This phenomenon is of great importance because glycated food proteins are not only a source of nutrients and energy but also display new properties and increased biological activities. Additionally, they are able to modify the bacterial intestinal ecosystem, thus affecting the general health status of a consumer.