Žužana Vaštag

In vitro study on digestion of pumpkin oil cake protein hydrolysate: Evaluation of impact on bioactive properties

In this work, a simulated gastrointestinal digestion of pumpkin oil cake protein hydrolysate prepared by alcalase (AH) was studied to evaluate the impact of the main gastrointestinal proteases on its antiradical and angiotensin I-converting enzyme (ACE) inhibitory activity. The in vitro digestion was performed in a model system under optimized reaction conditions, first by pepsin and then with α-chymotrypsin and trypsin, simultaneously. The treatment with the gastrointestinal proteases led to a significant increase of the degree of hydrolysis, up to 55.95 ± 3.1% in the final digest. After the digestion, the 2,2-azinobis3-ethylbenzo-thiazoline-6-sulphonic acid radical cation activity of AH was increased from 7.59 ± 0.1 to 10.25 ± 0.3 mM trolox equivalent antioxidant coefficient/mg (p < 0.05), while the ACE inhibitory activity was not affected, being 74.29 ± 1.25% (IC50 = 0.404 ± 0.014 mg/ml) (p>0.05) in the final digest. These results showed an advantage of AH to increase the antiradical and resist ACE inhibitory activity during digestion by main gastrointestinal proteases, appearing as promising bioactive food ingredient.

Characterization of Starch Edible Films with Different Essential Oils Addition

Abstract This study investigated properties of starch-based edible films with oregano and black cumin essential oil addition. Essential oils addition positively affected film swelling (decreased due to essential oil addition), mechanical properties (tensile strength decreased while elongation at break increased), and water vapor barrier properties (decreased along with essential oils addition). Control film did not have any biological activity, which proves the need for essential oils addition in order to obtain active packaging. Oregano oil was more effective in terms of biological activity. Endothermal peak, above 200°C, represents total thermal degradation of edible films. Diffraction pattern of control film showed significant destruction of A-type crystal structure. Addition of essential oils resulted in peak shape change: diffraction peaks became narrower. Principal Component Analysis has been used to assess the effect of essential oils addition on final starch-based edible films characteristics with the aim to reveal directions for the film characteristics improvement, since the next phase will be optimal film application for food packaging.

Microencapsulation Technology and Essential Oil Pesticides for Food Plant Production

Conventional agriculture is often characterized by heavy use of synthetic pesticides which usually become pollutants, thereby damaging the health of humans and ecosystems. Although pesticides are used to kill a particular target pest, many of them also harm nontargeted species. Essential oil-based pesticides have been used as contact toxicants, fumigants, attractants, or repellents. Because they are relatively nontoxic to vertebrates, they meet the criteria for “reduced risk” pesticides and are a part of sustainable agriculture. To overcome the instability of essential oils and to at least partially mimic the chemical compartmentalization in plants, microencapsulation techniques have been used. Microencapsulation protects sensitive materials that can suffer from degradation and enables its perseverance and controlled and gradual release.

Functional properties of pumpkin (Cucurbita pepo) seed protein isolate and hydrolysate

Pumpkin seed protein isolate (PSPI) was enzymatically hydrolysed by pepsin to obtain pumpkin seed protein hydrolysate, PSPH. Investigation on solubility, interfacial and emulsifying properties of both PSPI and PSPH was conducted under different conditions of pH (3–8) and ionic strength (0–1 mol/dm 3 NaCl). PSPI had the lowest solubility, i.e. isoelectric point (pI), at pH 5. PSPH had higher solubility than PSPI over whole range of pH and ionic strengths tested. Decrease in surface and interfacial tension evidenced that both proteins adsorb at air/protein solution and oil/protein solution interface. 20 % oil in water emulsions stabilized by 1 g/100cm 3 PSPI or PSPH solution were prepared at pH 3, 5 and 8 and ionic strength of 0 and 0.5 mol/dm 3 NaCl. PSPH stabilized emulsions from coalescence at all pH and ionic strengths tested. PSPI was able to stabilize emulsions at pH 3 and 0 mol/dm 3 NaCl and at pH 8, regardless of ionic strength while emulsions at pH 5 and both 0 and 0.5 mol/dm 3 NaCl and at pH 3 when ionic strength was increased separated to oil and serum layer immediately after preparation. All emulsions were susceptible to creaming instability.

Phenolic Acids in Pumpkin ( Cucurbita pepo L.) Seeds

Publisher Summary This chapter provides an evaluation of the nutritional properties of pumpkin seeds. Pumpkin seeds and seed extracts represent a complex mixture of substances, and their effects may not be attributed to just a few ingredients. It is significant for the treatment of BHP, a condition that commonly affects men 50 years and older and involves enlargement of the prostate gland. Pumpkin seeds also contain citrulline, which is attributed with an anti-edematous effect. Furthermore, some as yet not fully described ingredients have antimicrobial and anti-inflammatory activity, as well as a regulatory influence on the bladder musculature. Other effective ingredients are zinc, linoleic, oleic, palmitic, and stearic acids and magnesium salts. They are ubiquitous in pumpkin seeds, but the question of whether they are significant in the relief from BHP-associated discomfort remains unanswered. Pumpkins also contain biologically active components that include polysaccharides, proteins, and peptides. Phenolic acids are distributed in nature in their free and bound forms and are ubiquitous in plants. Despite the ubiquitous presence of phenolic acids in plant-based food and their role as dietary antioxidants, until recently the literature about the presence of phenolic compounds in pumpkin C. pepo has been limited. They represent 30% of polyphenols taken by diet and have an antioxidant capacity that is related to their health-promoting features. A certain profile of phenolic acids is also present in pumpkin seed and may contribute to the prevention or cure of different disorders in humans.

Optimization of Enzymatic Hydrolysis of Cucurbitin Using Response Surface Methodology: Improvement of the Functional Properties

Optimization of enzymatic hydrolysis of cucurbitin, extracted from pumpkin (Cucurbita pepo) oil cake with bromelain, was carried out by response surface methodology (RSM). Second-order polynomial model (R2=0.791) has been proposed for the effect of time (t), and enzyme/substrate ratio (E/S) on degree of hydrolysis (DH). Conditions for obtaining maximal value of DH were determined (E/S= 0.0132 (w/w), t= 42 min). Furthermore, according to the regression equation, conditions for production of hydrolysates with target DH values were chosen. Comparison of the functional properties of cucurbitin and its hydrolysates (DH= 10%, 20% and 30%) were carried out. The solubility of the hydrolysates gradually increased with the increase of DH, in pH range of 6–8. The hydrolysate with DH=10% had the best emulsifying properties (EA=0.632 ± 0.02 A500nm, ES= 44.2min), and extent of hydrolysis decreased both emulsifying activity and emulsifying stability. All studied hydrolysates exhibited higher oil-holding capacity and have improved foaming properties compared to the original protein. DH has influence on foam capacity. The highest foam capacity has hydrolysate with DH=20% (150.3±3.66 %). Obtained results suggest that limited protease hydrolysis of cucurbitin with bromelain produces the hydrolysates with improved functional properties and indicate their possible use in different food systems.