Structural Characterization, Technofunctional and Rheological Properties of Sesame Proteins Treated by High-Intensity Ultrasound.

Plant-derived proteins, such as those from sesame seeds, have the potential to be used as versatile food ingredients. End-use functionality can be further improved by high-intensity ultrasound treatments. The effects of high-intensity ultrasound on the properties of sesame protein isolates from cold-pressed sesame cake were evaluated. The SDS-PAGE demonstrated no significant changes in the molecular weight of proteins. Ultrasound treatments resulted in decreased particle size with a more uniform distribution, resulting in the exposure of hydrophobicity and free -SH groups and increased zeta potential. Although FTIR spectra of proteins were similar after ultrasonication, a partial increase in the intensity of the amide A band was observed. The ultrasound significantly (p < 0.05) affected the secondary structure of proteins. While optical micrographics revealed a dispersed structure with smaller particles after treatments, microstructural observations indicated more rough and irregular surfaces. Water solubility was improved to 80.73% in the sample subjected to 6 min of ultrasonication. Sesame protein solutions treated for 4 and 6 min exhibited viscoelastic structure (storage modulus (G') > loss modulus (G'')). In addition, the gelation temperature of proteins decreased to about 60-65 °C with increasing treatment time. Overall, ultrasound is a useful technique for the modification of sesame protein isolates.

Influence of pH and ionic strength on the bulk and interfacial rheology and technofunctional properties of hazelnut meal protein isolate.

The functional, bulk, and interfacial shear rheological properties of hazelnut protein isolate were studied at different pH values between 3.0 and 8.0 and ionic strength levels between 0.0 and 1.0 M. The results showed that pH significantly affected protein solubility, emulsion properties, water and oil holding capacities, foam stability, surface hydrophobicity, and free -SH groups. The highest surface hydrophobicity, free -SH groups, and better functional properties were observed at pH 8.0. Protein solubility also increased with increasing ionic strength up to 0.6 M. The emulsion and foam stability of hazelnut protein isolate showed similar changes with protein solubility. The flow behavior of hazelnut protein suspensions was found to be shear thinning with the highest consistency index at pH 3.0 and the lowest at pH 6.0, however, the ionic strength did not significantly affect the consistency coefficient but did cause a significant change in the flow behavior index, with the lowest value observed at 0.6 M. The best gel structure in hazelnut proteins was observed at pH 3.0 and 4.0. The addition of ions at 0.4 and 0.6 M concentrations resulted in an improved viscoelastic character. The hazelnut protein isolate was also found to form solid-like viscoelastic layers at both air-water and oil-water interfaces, with the interfacial adsorption behavior affected by both pH and ionic strength. Overall, these results suggest that pH and ionic strength have significant effects on the functional and rheological properties of hazelnut protein isolate, which may have the potential as an auxiliary substance in food systems.

Effect of cold-pressed hazelnut cake incorporation on the quality characteristic of meat emulsion system and its potential application for frankfurter-type beef sausages.

This research was performed to investigate the effect of hazelnut cake (HC) as a cold press waste product on the physicochemical and textural properties of the frankfurter-type sausages during cold storage. According to the highest emulsion capacity (174.14 mL oil/g), emulsion stability (79.86%), and optimum rheological results obtained in emulsions, 1% HC concentration was selected for the utilization in the sausage formulation. HC added sausage was compared with the control sample at 4°C for 60 days of storage. HC addition increased the hardness and chewiness properties and decreased weight loss of sausages during storage. The incorporation of HC in formulation slowed down the increase in malondialdehyde and conjugated dienes concentrations after the 15th day of storage compared to the control sausages. The results demonstrated that HC presented a good opportunity for protecting the quality parameters of emulsified meat products during storage.

Production and characterization of biodegradable bi-layer films from poly(lactic) acid and zein.

Recently, packaging industry has turned to biodegradable packaging, and poly(lactic acid) has become the most remarkable polymer. However, the high oxygen permeability of PLA films significantly limits their use. Therefore, this study, it was aimed to improve the oxygen barrier properties of PLA films without adversely affecting the mechanical and water vapor barrier properties. Biodegradable PLA-Zein bi-layer films were produced by changing PLA and zein thickness. Transparent and UV barrier bi-layer films were obtained. Mechanical properties of PLA films were improved by the production of bi-layer films. Water vapor permeability of bi-layer films increased whereas the permeance decreased with zein coating of PLA. Multi-criteria decision hierarchy was used to select the best bi-layer films based on mechanical, permeance, and opacity results. Oxygen barrier properties of PLA film significantly improved by zein coating, and hydrophobicity of PLA film was not affected by zein coating. The crystallization and melting temperatures of films decreased when compared to PLA films, supporting the mechanical results. Homogeneous, non-porous, and smooth film surface was obtained and zein layer was in good compatibility with PLA layer. These results suggest that zein coatings could be used to decrease oxygen permeability of PLA films without negatively affecting other properties.

Enhanced Functionality and Bio-Accessibility of Composite Pomegranate Peel Extract-Enriched "Boba Balls".

"Boba balls" or pearls have recently gained popularity for beverages or food toppings. "Boba balls" could be developed into functional foods by the encapsulation of bioactive compounds. In this study, gelatin/sodium alginate composite "Boba balls" enriched with pomegranate peel extract (PPE) at different concentrations (0, 1, 2, and 3%) were prepared. They were characterized in terms of physical, rheological, textural, morphological, and sensory properties, as well as in vitro digestion, bio-accessibility, and release kinetic of PPE. Adding PPE improved the "Boba" mix's viscoelasticity and decreased the "Boba balls"' hardness. The increasing PPE ratio significantly (p < 0.05) increased the antioxidant capacity and total phenolic content. The addition of PPE preserved the spherical shape of the "Boba balls", and as the PPE ratio increased, new junction zones were observed in SEM images. The in vitro digestibility of PPE was significantly (p < 0.05) improved by preserving PPE from the mouth and gastric medium, and "Boba balls" showed the highest release and bio-accessibility in the intestinal medium. Consequently, PPE as a by-product could be successfully used at 2% concentration for enhancing the functionality and bio-accessibility of "Boba balls" without affecting sensory properties.

Potential Use of High Pressure Homogenized Hazelnut Beverage for a Functional Yoghurt-Like Product.

Hazelnut beverage is a plant-based beverage produced from hazelnut cake as a by-product obtained after cold press extraction. It has high nutritional value and a significant percentage of consumers show interest in it due to its health benefits. In this study, hazelnut beverage manufactured from by-products of hazelnut oil industry was incorporated into functional yoghurt production. Five formulations (ratio of 1/0, 3/1, 2/1, 1/1, 0/1, v/v, cow milk/hazelnut beverage) of yoghurt-like products were prepared to indicate the storage period of the samples and the analysis performed. For yoghurt production, hazelnut beverage and cows' milk were standardized to 14.5 g 100 g-1 with skimmed milk powder. The use of hazelnut beverage in yoghurt production negatively affected L. bulgaricus counts. Water holding capacity and viscosity values were improved by using hazelnut beverage. Increasing hazelnut beverage concentration led to an increase in the total phenolic compounds and antioxidant activity, malic acid levels and also unsaturated fatty acids, especially oleic and linoleic acid. Using the ratio of 3/1 was found the best in view of appearance, flavor and overall acceptability. Based on the structural, rheological and sensorial properties, this study could guide the dairy industry to use hazelnut beverage obtained from hazelnut cake.

Application of high-pressure homogenization (HPH) to modify functional, structural and rheological properties of lentil (Lens culinaris) proteins.

The ability of high-pressure homogenization (HPH) to modify the functional, structural and rheological properties of lentil protein isolate (LPI) suspensions were investigated. Protein patterns remained unchanged with HPH treatment. Particle size significantly decreased up to 100 MPa treatment and size distribution was mono-modal after 50 MPa. Microstructural images revealed that increasing pressure from 50 to 150 MPa caused further unfolding of protein particles, which well supported to water solubility, emulsifying, foaming and particle size results. LPI suspensions had shear thinning behavior and results were well fitted to Ostwald de-Waele model (R2 ≥ 0.989). Apparent viscosity and homogenization pressure were modeled with exponential and sigmoidal functions (R2 ≥ 0.983). However, weak gel-like structure was observed from all samples due to G' > G″, and higher homogenization pressures than 50 MPa caused more pronounced gelation after 51.78 °C. These results stated that HPH treatment has a good potential to modify the functional, structural and rheological properties of LPI suspensions.

Performance of mechanically deboned chicken meat protein coatings containing thyme or clove essential oil for storage quality improvement of beef sucuks.

The performance of mechanically deboned chicken meat protein (MDCM-P) coatings containing thyme (TEO) or clove essential oils (CEO) was investigated to improve the storage quality of heat treated sucuks during 45 days of storage at 4 °C. The sucuk slices were divided to 4 groups as uncoated, coated with MDCM-P solution, coated with MDCM-P solution containing 1.5% TEO and MDCM-P solution containing 1.5% CEO. Physical, chemical and microbial properties of sucuk samples were analyzed on 0, 15, 30 and 45 days of storage. Results indicated that the weight loss, pH, thiobarbituric acid reactive subtances, total viable and psychrotrophic bacteria counts increased, while a* and b* values and water activity decreased with storage time (p < .05). In all analysis periods, these changes were slowed down with coating applications containing essential oils, but the slowest changes were observed in coated sucuks with MDCM-P solution containing 1.5% CEO. Therefore, MDCM-P coatings containing CEO could improve the storage quality of heat treated sucuks at refrigerator.

Influence of thermosonication (TS) process on the quality parameters of high pressure homogenized hazelnut milk from hazelnut oil by-products.

Hazelnut, an important source of nutrition, is reasonably expensive for hazelnut milk production. Hazelnut cake, a by-product from hazelnut oil production by cold press extraction technique, does not contain any chemical residue and can be used for hazelnut beverage production. This study investigates the effects of thermosonication process on the quality parameters of hazelnut milks and also compares the observed results with the conventional thermal process. Different thermosonication conditions at different amplitude levels (40 and 60% amplitudes for 5, 10, 15, 20 and 25 min and 80% amplitude for 3, 5, 10 and 15 min) were studied for physicochemical and rheological properties, as well as microbial inactivation and bioactive compounds of hazelnut milk produced from the cold pressed hazelnut cake as byproduct of oil production. In general, sonication process significantly improved the total phenolic compounds, antioxidant activity, appearance and structural properties like syneresis, sedimentation, viscosity and consistency of samples. The application of thermosonication at 60% amplitude for 25 min and 80% amplitude for 15 min achieved complete inactivation of microorganisms (total aerobic mesophilic bacteria and yeast-mould). Complete inactivation of microorganisms was also achieved by conventional pasteurization at 85 °C, but this treatment caused some undesirable changes such as loses of bioactive compounds and deterioration of structural properties. The findings of the present study indicate that thermosonication can be successfully utilized for commercial processing of hazelnut milk with improved quality. This technique allows the production of hazelnut milks in safety and quality standards with highly nutritious then the conventional product.

Antimicrobial Carvacrol in Solution Blow-Spun Fish-Skin Gelatin Nanofibers.

Carvacrol is a volatile monoterpenic phenol and main component of oregano essential oil that shows nonspecific antimicrobial activity against foodborne pathogenic bacteria. Fish-skin gelatin (FSG) nanofibers encapsulating carvacrol (15%, 20%, 25%, and 30%, w/w FSG) were successfully prepared via solution blow-spinning (SBS) technique using lecithin (2.475% wb) as the surfactant. FSG emulsions with lower carvacrol ratios (5% and 10%) showed higher values in particle size and surface tension as well as lower values in viscosity and modulus, which led to failure of maintaining nanofibers shape. The formed carvacrol-FSG nanofibers showed round and smooth morphologies with average fiber diameters ranging from 103.2 to 138.1 nm as the carvacrol ratio increased from 15% to 30%. Carvacrol was evenly dispersed within the interior of nanofiber matrix. All carvacrol-FSG nanofibers showed inhibitive effects against the growth of Escherichia coli, Salmonella enterica, and Listeria monocytogenes. Moreover, nanofibers with lower carvacrol ratios showed bigger inhibition zones for E. coli and L. monocytogenes (20 mm compared with 12.5 mm for lowest to highest carvacrol ratios, respectively). Nanofibers stored at 20 °C (51% RH) showed better retention (40% to 60%) for carvacrol during the first 4 weeks of storage, while nanofibers stored at 2 °C (70% RH) showed better retention (10% to 30%) at the end of storage. PRACTICAL APPLICATION: Results obtained in the study may help with antimicrobial carvacrol addition levels for gelatin fiber preparation using solution blow spinning (SBS) method. SBS gelatin fibers with added antimicrobials have potential applications for food packaging and medical wound dressing.

Effect of ultrasound treatment on the properties of nano-emulsion films obtained from hazelnut meal protein and clove essential oil.

Hazelnut meal protein (4% (w/v)) and clove essential oil (CEO) (3% (v/v)) were homogenized with ultrasound (US) at different times (2, 4 and 6 min) and amplitudes (50, 75 and 100%) to obtain nano-emulsion films. Film forming nano-emulsions (FFNs) were analyzed for average particle size (Dz) and zeta potential, and edible film characterization were evaluated depending on US treatment, as well as antibacterial and antioxidant activities. Dz values and zeta potential of FFNs decreased with increasing acoustic energy delivered to nano-emulsion system. Thickness and water solubility of films significantly decreased with increasing US treatment. Films became more transparent depending on US treatment probably due to particle size reduction. Tensile strength (TS) of films significantly increased with US treatment, while elongation at break (EAB) slightly increased. Microstructure of films became more homogeneous after US treatment and caused to lower water vapor permeability. Enrichment with CEO has given the films antibacterial activity against L. monocytogenes, B. subtilis, S. aureus, P. aeruginosa and E. coli, and antioxidant activity, and US application has improved these activities. US technology can be used to improve mechanical, barrier and antimicrobial properties of hazelnut meal protein based edible films enriched with CEO.

Edible Packaging Film Derived from Mechanically Deboned Chicken Meat Proteins: Effect of Transglutaminase on Physicochemical Properties.

In this study, effect of transglutaminase (TGase) addition on physical, water barrier, optical and mechanical properties of mechanically deboned chicken meat protein (MDCM-P) films was investigated. When TGase was added to the films, the thickness increased, but the solubility decreased. Films treated with TGase exhibited higher water vapor permeability than control film (p<0.05). When TGase concentration increased, the L* values of films decreased, but a* and b* values increased. All films showed very good barrier properties against UV light. The highest tensile strength was obtained in MDCM-P films containing 3% TGase (p<0.05). The elongation at break values increased with the TGase concentration increasing from 1 to 3%, but decreased at higher enzyme concentration (p<0.05). The addition of TGase altered molecular organization and intermolecular interaction in the film matrix. TGase treated films showed smoother and ordered surface structure and homogeneous and compact microstructure. The results indicated that TGase use can be an effective approach in improving the solubility and mechanical properties of MDCM-P films.

Evaluation of the Nutritional and Storage Quality of Meatballs Formulated with Bee Pollen.

In this study, the nutritional and storage quality of meatballs formulated with different levels (0, 1.5, 3.0, 4.5 and 6.0%) of bee pollen were investigated during storage at 41℃ for 9 d. Protein content of meatballs increased, while moisture content decreased with increased pollen. The addition of pollen improved cooking loss but decreased the redness (Hunter a value) and sensory scores. Textural parameters (hardness, springsness, gumminess, and chewiness) were affected by pollen addition and the hardness and gumminess values of meatballs decreased as the pollen content increased. While C18:0 content of meatballs slightly decreased with pollen addition, C18:2n-6c, C18:3n-3, C20:5n-3, and PUFA contents increased. The PUFA/saturated fatty acids (P/S) ratio increased from 0.05 in the control to 0.09 in meatballs with 6.0% pollen. The n-6/n-3 ratio decreased from 11.84 in the control to 3.65 in the meatballs with 6.0% pollen. The addition of pollen retarded the lipid oxidation and inhibited the bacterial growth in meatballs. The pH, redness, TBA value and total aerobic mesophilic bacteria, coliform bacteria and S. aureus counts values changed significantly during storage. The results suggest that bee pollen could be added to enhance the nutritional and storage quality of meatballs with minimal changes in composition and/or sensory properties.