Mirjana B. Pesic

Profile and functional properties of seed proteins from six pea (Pisum sativum) genotypes.

Extractability, extractable protein compositions, technological-functional properties of pea (Pisum sativum) proteins from six genotypes grown in Serbia were investigated. Also, the relationship between these characteristics was presented. Investigated genotypes showed significant differences in storage protein content, composition and extractability. The ratio of vicilin:legumin concentrations, as well as the ratio of vicilin + convicilin: Legumin concentrations were positively correlated with extractability. Our data suggest that the higher level of vicilin and/or a lower level of legumin have a positive influence on protein extractability. The emulsion activity index (EAI) was strongly and positively correlated with the solubility, while no significant correlation was found between emulsion stability (ESI) and solubility, nor between foaming properties and solubility. No association was evident between ESI and EAI. A moderate positive correlation between emulsion stability and foam capacity was observed. Proteins from the investigated genotypes expressed significantly different emulsifying properties and foam capacity at different pH values, whereas low foam stability was detected. It appears that genotype has considerable influence on content, composition and technological-functional properties of pea bean proteins. This fact can be very useful for food scientists in efforts to improve the quality of peas and pea protein products.

Characterization of Proteins from Grain of Different Bread and Durum Wheat Genotypes

The classical Osborne wheat protein fractions (albumins, globulins, gliadins, and glutenins), as well as several proteins from each of the four subunits of gliadin using SDS-PAGE analyses, were determined in the grain of five bread (T. aestivum L.) and five durum wheat (T. durum Desf.) genotypes. In addition, content of tryptophan and wet gluten were analyzed. Gliadins and glutenins comprise from 58.17% to 65.27% and 56.25% to 64.48% of total proteins and as such account for both quantity and quality of the bread and durum wheat grain proteins, respectively. The ratio of gliadin/total glutenin varied from 0.49 to 1.01 and 0.57 to 1.06 among the bread and durum genotypes, respectively. According to SDS-PAGE analysis, bread wheat genotypes had a higher concentration of α + β + γ-subunits of gliadin (on average 61.54% of extractable proteins) than durum wheat (on average 55.32% of extractable proteins). However, low concentration of ω-subunit was found in both bread (0.50% to 2.53% of extractable proteins) and durum (3.65% to 6.99% of extractable proteins) wheat genotypes. On average, durum wheat contained significantly higher amounts of tryptophan and wet gluten (0.163% dry weight (d.w.) and 26.96% d.w., respectively) than bread wheat (0.147% d.w. and 24.18% d.w., respectively).

Functional Properties of Pea (Pisum sativum, L.) Protein Isolates Modified with Chymosin

In this paper, the effects of limited hydrolysis on functional properties, as well as on protein composition of laboratory-prepared pea protein isolates, were investigated. Pea protein isolates were hydrolyzed for either 15, 30 and 60 min with recombined chymosin (Maxiren). The effect of enzymatic action on solubility, emulsifying and foaming properties at different pH values (3.0; 5.0; 7.0 and 8.0) was monitored. Chymosin can be a very useful agent for improvement of functional properties of isolates. Action of this enzyme caused a low degree of hydrolysis (3.9–4.7%), but improved significantly functional properties of pea protein isolates (PPI), especially at lower pH values (3.0–5.0). At these pH values all hydrolysates had better solubility, emulsifying activity and foaming stability, while longer-treated samples (60 min) formed more stable emulsions at higher pH values (7.0, 8.0) than initial isolates. Also, regardless of pH value, all hydrolysates showed improved foaming ability. A moderate positive correlation between solubility and emulsifying activity index (EAI) (0.74) and negative correlation between solubility and foam stability (−0.60) as well as between foam stability (FS) and EAI (−0.77) were observed. Detected enhancement in functional properties was a result of partial hydrolysis of insoluble protein complexes.

Characterization of proteins from kernel of different soybean varieties

BACKGROUND Total soybean proteins, storage proteins, glycinin (11S) and β-conglycinin (7S) fractions and their respective subunits in seven soybean varieties were analyzed. In this work we also present the correlation between concentration and activity of bioactive proteins, lipoxygenase and proteinase inhibitors. RESULTS Glycinin and β-conglycinin comprise about 750 g kg(-1) of the bean storage protein and as such account for both quantity and quality of the kernel protein. The 11S concentration of the varieties studied ranged from 503.4 to 602.9 g kg(-1) and those of 7S varied from 178.2 to 230.6 g kg(-1) of total extractable proteins. The ratio of 11S/7S proteins varied from 2.43 to 3.29 among the varieties. A very strong positive correlation was found between the concentration of Kunitz trypsin inhibitor and activity of total trypsin inhibitor (r = 0.96). However, lipoxygenase concentration did not show a strong correlation with lipoxygenase activity. CONCLUSION It appears that among the seven ZP soybean genotypes there are genotypes with different amounts of subunits that should be bred in the future for a desired level of protein components.

Bioactive Proteins and Energy Value of Okara as a Byproduct in Hydrothermal Processing of Soy Milk

The nutritional properties of raw okara obtained as a byproduct from six soybean varieties during hydrothermal cooking (HTC) of soy milk were assessed. The composition and residual activity (rTIA) of trypsin inhibitors (TIs), contents of lectin, proteins, fats, and carbohydrates, and energy values (EV) were correlated with the respective physicochemical properties of soybean and okara. Kunitz (KTI) and Bowman-Birk (BBI) TIs both comprised okara rTIA. TIs content was higher in okara (5.19-14.40%) than in soybean (3.10-12.17%), which additionally enriched okara by cysteine. Contents of KTI (r = 1.00;p < 0.05) and BBI (r = 0.89;p < 0.05) as well as BBI monomeric (r = 0.89;p < 0.05) and polymeric forms (r = 0.95;p < 0.05) in okara and in soybean were strongly correlated. Low urease index activity indicated that okara was heated adequately to inactivate antinutritional factors. The proximate composition of raw okara, advantageous rTIA, and a very low EV (2.74-3.78 kJ/g) qualify this byproduct for potential application in food preparation as a functional ingredient in dietary products.

Mineral content of bee pollen from Serbia

In this study we analysed mineral composition of bee pollen of different plant origin collected across Serbia using inductively coupled plasma - optical emission spectrometry. The most abundant elements were potassium, calcium, and magnesium. The samples were also exceptionally rich in iron and zinc, which are very important as nutrients. Judging by our findings, mineral composition of bee pollen much more depends on the type of pollen-producing plant than on its geographical origin. U ovom radu analiziran je mineralni sastav pčelinjega peluda različitoga biljnoga podrijetla prikupljenoga diljem Srbije primjenom inducirano spregnute plazme - optičke emisijske spektroskopije. Najzastupljeniji elementi su kalij, kalcij i magnezij. Uzorci su također iznimno bogati željezom i cinkom, što povećava njihovu nutritivnu vrijednost. Prema našim saznanjima, mineralni sastav pčelinjega peluda puno više ovisi o vrsti biljaka koje proizvode pelud nego o njegovu zemljopisnom podrijetlu.

Composition of proteins in okara as a byproduct in hydrothermal processing of soy milk.

Protein quality, based on its subunit composition, in okara obtained as a byproduct during hydrothermal cooking of soy milk was assessed. The composition of 7S and 11S protein fractions was correlated with the physicochemical properties of protein in okara produced from six soybean varieties. The basic 7S globulin (Bg7S) and 11S protein were two main proteins in okara. Investigated soybean genotypes produced okara with mainly acidic A(5) and basic B(1,2,4) polypeptides of 11S proteins. Soybean 11S content was not an indicator of okara protein recovery or extractability. Of all tested relationships, extractable soluble protein content of okara was influenced only by soybean Bg7S (r = 0.86; p < 0.05) and its light subunit contents (r = 0.93; p < 0.05). Okara protein recovery depended on Bg7S heavy subunit content in soybeans (r = 0.81; p < 0.05). The high quantity of vegetable protein in okara (around 35%) and very high protein extractability (around 85%) qualify this byproduct for potential application in food preparation as a functional ingredient.

Mineral elements, lipoxygenase activity, and antioxidant capacity of okara as a byproduct in hydrothermal processing of soy milk.

Minerals and antioxidative capacity of raw okara that was obtained as a byproduct from six soybean varieties during hydrothermal cooking (HTC) of soy milk were assessed. Lipoxygenase (Lox), an enzyme deteriorating the sensory characteristics of okara, was also investigated. All genotypes had very similar concentrations of Lox (4.32-5.62%). Compared to raw soybeans, the applied HTC significantly reduced Lox content in okara (0.54-0.19%) and lowered its activity to 0.004-0.007 μmol g(-1) min (-1). Correlation between the content of Lox in soybeans and that in okara (r = 0.21;p < 0.05) was not registered. This indicates that the content of this enzyme in okara depended much more on the technological process than on soybean genotype. Very strong correlation (r = 0.99; p < 0.05) between okara Lox content and its activity was found. The most abundant minerals in raw okara were potassium (1.04-1.21 g/100g), phosphorus (0.45-0.50 g/100 g), calcium (0.26-0.39 g/100 g), and iron (5.45-10.95 mg/100 g). A very high antioxidant capacity (19.06-29.36 mmol Trolox kg(-1)) contributes to the nutritional value of raw okara.

Mold/aflatoxin contamination of honey bee collected pollen from different Serbian regions

Assessment of microbiological quality of bee collected pollen is very important, because of its use as a supplement in the human diet. In this study, 26 samples collected from different location in Serbia were tested for the presence of mold through mycologial analysis. The presence of aflatoxin B1, one of the most dangerous and the most widespread mycotoxin was also determined. It was established that 10 of the investigated samples were contaminated with some genera or species of mold, but all of the investigated samples were contaminated with aflatoxin B1. Considering that there is no unique and official procedure for mycological analysis of bee collected pollen, these findings suggest the need for their establishment. Mycological analysis should be followed by mycotoxicological analysis since the absence of mold does not confirm the absence of aflatoxin B1 in bee pollen.

The fatty acid profile of Serbian bee-collected pollen – a chemotaxonomic and nutritional approach

The fatty acid profile, its relation to botanical origin and nutritional characteristics of bee-collected pollen from Serbia was determined. Twenty different fatty acids were detected. Depending on the palynological origin, the fatty acid (FAs) composition varied greatly. Three groups of pollen samples can be differentiated on the basis of Categorical principal component analysis. The first group was characterized by the presence of Fraxinus sp. pollen as predominant type and Zea mays as an accompanying pollen type and a high level of polyunsaturated FAs. Rannunculaceae, Apiaceae and Asteraceae family pollen, Ambrosia, Plantago, Sophora and Helianthus annuus pollen influenced the presence of saturated FAs and separation of the second group of samples. Pollen of plants belonging to the Fabaceae and Brassicaceae families had significant influence on constitution of the third group of samples with saturated and unsaturated FAs. The most abundant saturated, mono- and poly unsaturated fatty acids were palmitic, oleic and linolenic acid, respectively.