Multi-layer encapsulation of pumpkin (Cucurbita maxima L.) seed protein hydrolysate and investigating its release and antioxidant activity in simulated gastrointestinal digestion

Because of their high protein content, easy access and low cost, pumpkin seeds are a valuable raw material for the preparation of antioxidant protein hydrolysates. Micro-coating is an effective method to protect bioactive compounds against destruction. In order to strengthen the alginate hydrogel network loaded with pumpkin seed protein hydrolysate (PSPH), CMC was added as part of its formulation in the first step, and chitosan coating was used in the second step. Then, swelling amount, release in the simulated gastrointestinal environment (SGI), antioxidant activity after SGI, Fourier transform infrared spectroscopy (FTIR), zeta potential, dynamic light scattering (DLS), polydispersity index (PDI) and scanning electron microscopy (SEM) of the samples were evaluated. The results showed that, the swelling amount of the chitosan-alginate hydrogel was lower than the chitosan-alginate-CMC sample, and with the increase in chitosan concentration, the swelling amount decreased. The release amount in the chitosan-alginate sample was higher than that in the chitosan-alginate-CMC sample, and with the increase in chitosan concentration, the release rate decreased. Also, the amount of release increased with the passage of time. The highest antioxidant activity belonged to the chitosan-alginate sample in SGI, and it increased with increasing the chitosan concentration. All findings demonstrated that the use of multi-component hybrid systems is a useful method for the protection of bioactive compounds against destruction, their antioxidant activities and their release behavior.

Composite alginate-based hydrogel delivery of antioxidant pumpkin protein hydrolysate in simulated gastrointestinal condition

Pumpkin seeds are rich in protein (24-36.5%). Some of them are consumed as nuts, while others are regarded as waste and used for feeding animals. Protein hydrolysates from pumpkin seeds possess some bioactive properties, such as anti-oxidant activity. In this work, various composite alginate hydrogels contain Aloe vera, CMC, and tragacanth have been employed to protect PSPH against degradation in simulated gastrointestinal digestion (SGI) and regulate its release rate. The encapsulation efficiency of PSPH in plain alginate and beads with Aloe vera, CMC, and tragacanth combinations was 71.63, 75.63, 85.07, and 80.4%, respectively. The release rate of the plain alginate beads was %30.23 in the SGF and %52.26 in the SIF, and decreased in the composite-based beads. The highest decreasing rate in the antioxidant activity during SGI was observed in free PSPH, and the decreasing rate slowed down in the alginate-based composites. The swelling rate in plain alginate was %-23.43 and %25.43 in the SGF and SIF, respectively, and increased in the composite-based beads. The FTIR spectra of hydrogels before and after loading with PSPH showed identical absorption patterns and were similar to each other. Based on the data for SEM, it was revealed that substituting other polymers in polymer combinations with alginates resulted in a porosity reduction of the beads and smoother and more uniform surfaces. Based on the results, the combination of polysacchared with alginate could protect and increase the applicability of PSPH as a functional component in the food industry.

Changes in emulsifying properties of caseinate-Soy soluble polysaccharides conjugates by ultrasonication

This research aimed to assess the impact of ultrasonication on the emulsifying ability of a conjugate system composed of sodium caseinate and soluble soy polysaccharides. The study analyzed the characteristics of the particles and evaluated the emulsions produced using nanoconjugates. The results showed that ultrasonication improved the contact angle (63.7°) and decreased particle size (75 nm), resulting in more effective emulsifying efficiency. At a 2 % concentration of the nanoconjugates, stable emulsions with a 50 % oil content were successfully formed through complete coverage of the droplets' surface, and no oil release was observed. Moreover, the emulsions' creaming index remained below 25 % even after 60 days of storage. The stability of the nanoconjugate-based emulsions depended on the concentration of nanoconjugates, with an optimal concentration of 4 %. These findings suggest that the nanoconjugates have great potential as a natural stabilizer for emulsion-based products.

Physicochemical, Thermal, and Morphological Properties of Chitosan Nanoparticles Produced by Ionic Gelation

Chitosan nanoparticles (CSNPs) can be widely used in the food, pharmaceutical, and cosmetic sectors due to their high performance, unique properties, and high surface area. In this research, CSNPs were produced by the ionic gelation method and using sodium tripolyphosphate (STPP) as an appropriate technique compared to the conventional methods. To evaluate the effects of various factors on the size, zeta potential (ZP), and optimal synthesis conditions, different concentrations of CS (1, 3, and 5 mg/mL), STPP (0.5, 0.75, and 1 mg/mL), and CS to STPP ratio (1:1, 3:1, and 5:1) were applied and optimized using the response surface methodology. The size of CSNPs was increased by using higher concentrations of CS, STPP, and CS/STPP ratios. The value of ZP was determined positive and it increased with increasing CS concentrations and CS/STPP ratios. ATR-FTIR spectra revealed interactions between CS and STPP. The DSC thermogram of CSNPs showed a double sharp endothermic peak at about 74.5 °C (ΔH = 122.00 J/g); further, the TGA thermograms indicated the total weight loss of STPP, CS, and CSNPs as nearly 3.30%, 63.60%, and 52.00%, respectively. The XRD data also revealed a greater chain alignment in the CSNPs. Optimized, the CSNPs can be used as promising carriers for bioactive compounds where they also act as efficient stabilizers in Pickering emulsions.

Improving the emulsifying properties of sodium caseinate through conjugation with soybean soluble polysaccharides

This study was conducted to investigate the impact on the techno-functionality over sodium caseinate (NaCS) when are conjugated with soluble soybean polysaccharides (SSPS). NaCS/SSPS conjugates were prepared through the Maillard reaction using dry heating. The formation of covalent binding between NaCS and SSPS and structural changes of NaCS during glycation were confirmed via SDS-PAGE and ATR-FTIR. A positive correlation was observed between the increase in the browning index of samples and Amadori compounds formation over time, based on the colorimetric results. Emulsions stabilization using conjugates with a higher NaCS/SSPS ratio led to a decreasing trend in the droplets' size and creaming index. Meanwhile, higher viscosity and shear-thinning behavior were observed in conjugate-based emulsions. Finally, conjugates prepared with the NaCS/SSPS ratio of 9/1 at an incubation time of 24 h presented a higher pH and thermal stability and better performance in emulsion stabilization in comparison with each of the biopolymers alone.

Production of d-limonene-loaded Pickering emulsions stabilized by chitosan nanoparticles

Recently, Pickering emulsions have been considered as an efficient method to maintain and protect the functional properties of essential oils against the harsh conditions. In this research, the encapsulation of d-limonene, as an aromatic component with several distinct properties, was conducted through optimizing the production of Pickering emulsions stabilized by chitosan nanoparticles (CSNPs) and using the response surface methodology; independent variables were different concentrations of CSNPs (0.43, 0.25, and 0.07% w/v) and ratio of d-limonene to Pickering emulsions (5, 15, and 25%). The stability of the emulsions increased at higher contents of the CSNPs. By increasing the concentration of CSNPs and ratio of d-limonene to Pickering emulsion, viscosity of Pickering emulsions was considerably increased. Considering the chemical interactions, thermal behaviors, and crystallinity of samples, CSNPs can be used as an appropriate stabilizer for d-limonene-loaded emulsions and a food grade delivery carrier for the bioactive compounds.