نشریه مهندسی بیوسیستم ایران
سال پنجاه و یکم شماره 1 (بهار 1399)

Herbal compounds, so-called phyto-constituents, illustrate poor stability and absorption. Niosomes, which are made of nonionic surfactants, create better chemical and stability conditions, higher absorption rate and bioavailability besides lipid vesicles. This study covers the preparation and characterization of phyto-niosomes of grape stem extract by modified thin film hydration technique. The developed formulations were statistically optimized using response surface methodology, The applied Box–Behnken design had three factors with three levels for each factor. Hydrophilic-lipophilic balance (HLB), phytosterol percent and extract amount were selected as the formulation variables. The results showed that extract concentration was the most important parameter affecting the encapsulation efficiency and poly dispersity index. Also HLB had the most important effects on the particle size. The optimized phyto-niosomes showed vesicle size, entrapment efficiency and poly dispersity index (PDI) of 173nm, 72% and 0.32 respectively .Before the encapsulation process, extracts of dried stems were prepared by Green extraction method and phenolic composition was identified with LC-MS/MS. Indeed, it was found that phyto-niosomes could be represented as an inexpensive and efficient nano vesicular carrier for nutraceuticals delivery in food industry.

The aim of this research was to develop an antimicrobial active packaging for shelf life extension of button mushrooms (Agaricus bisporus). TiO2 nanoparticles at three levels of 0, 0.5 and 1.5% were added to the low density polyethylene (LDPE) film and nanocomposite films were produced by blowing extrusion method. These films were used for packaging of fresh mushrooms. Also, UV irradiation was used on the packaged samples for 15 min to stimulate the antimicrobial activity of the films. Evaluation of antimicrobial properties of films revealed that the inhibitory effect against growth of E. coli and S. aureus increased by increasing TiO2 content and also by UV irradiation. Mushroom samples were stored for 15 days at refrigerator and physicochemical and microbial tests were applied on them. Weight loss, decreasing of phenolic compounds and also losing of vitamin C were decreased by using nanocomposite films and this effect increased by increasing TiO2 content. Browning index and color difference with fresh mushroom was the lowest for 1.5% TiO2 loaded and UV irradiated samples. Microbial counts of mushrooms increased during storage but active films were able to control this increment. Generally, this research indicated that the using of TiO2 in the LDPE film as a non-contact active packaging along with UV irradiation is able to increase the shelf life of mushroom and preserve its quality attributes during the supply period.

Kiwifruit peel extract was extracted using ultrasound bath and probe at 50 and 80% intensities. The extract obtained using ultrasound probe at 80% intensity had the highest extraction efficiency (42.19%). Bath ultrasound (265.88 mg/g) and probe at 80% intensity (298.46 mg/g) had the least and highest amount of free phenolic compound, respectively. Bath ultrasound (265.88 mg/g) and probe at 80% intensity (298.46 mg/g) had the highest amount of free phenolic compound. Acid hydrolysis (55.79 to 63.83 mg / g) was more effective in separating the bounded phenols than alkaline hydrolysis (54.39 to 61.92 mg/g). The antioxidant activity of extracted phenols was measured at 100 to 800 mg/L of concentrations by using two free radical scavenging method (DPPH) and iron reduction assay. Increasing the concentration of phenolic compounds in both free and bounded phenols increased the rate of iron reduction and free radical scavenging of DPPH. The highest antioxidant activity was observed in bounded phenols. A concentration of 800 mg/L of each phenol was used to encapsulation with Lepidiumsativum L. seed gum. The encapsulation efficiency of phenols was 51.96 to 82.36% and the highest efficiency was for phenol bounded sample and acid hydrolyzed ultrasound at 80% intensity. Zeta potential in all samples was negative and the particles were nanometer sized (less than 172.3 nm). The results of this study showed that Lepidiumsativum L. seed gum is a good wall for encapsulation of free and bounded phenols of kiwifruit peel extract and the acid-bound phenolic samples using probe ultrasound at 80 and 50% intensities and also free phenol obtained with bath ultrasound can be used as antioxidant compounds in food products.

By adding different amounts of the PPE (0, 0.3, 0.5, 1, 1.5, 2, 2.5 and 3 mL) to egg white, the foaming capacity at the optimum concentration of 1 mL of the extract, equivalent to 25.3 mg of poly phenol in samples with the pH of 9.7 and 4.5 was 1166, 1244, and 1579%, and the stability of the foam was 62.5, 75 and 77.6%, respectively. The results show that at acidic pH, the foaming capacity and stability of the egg white were the maximum due to the closeness of the pH of the egg white to the isoelectric pH of ovalbumin in the presence of PPE. Nevertheless, with the addition of phenolic extract to a concentration above optimum, the foaming capacity of the egg white becomes even lower than the foaming capacity of the control sample (no additives), but the increasing trend of foam stability continued, reaching a peak of 81.2%.