encapsulation

The current work aims to compare the effect of essential oil (pure and emulsified) Nepeta glomerulosa as natural preservatives for improving the shelf life of high-fat mayonnaise during 6 weeks of storage at 35 ºC. The nanoemulsion of Nepeta glomerulosa essential oil was prepared by the ultrasound cavitation method and physical properties were determined. Soy oil was substituted by 0.5 %w/w of the Nepeta essential oil or its nanoemulsion to compare the effect of natural and chemical (BHT and sodium-benzoate/potassium-sorbate) preservatives on the chemical (pH, acidity, peroxide-value, thiobarbituric acid-reactive-substances), microbial (acid-resistant bacteria, heterofermentative lactic acid bacteria, Escherichia coli, mold and yeast content, and salmonella) and sensory properties of mayonnaise. 1,8-Cineole (26.9%), α-Pinene (7.3%), and Limonene (6.8%) were the main compounds of this essential oil. The mean droplet diameter, PDI and viscosity of Nepeta nanoemulsions were 191.95 nm, 0.255, and 1.03 cP, respectively. The addition of the essential oil (pure or emulsified) significantly improved the oxidative stability of mayonnaise. There was no significant difference between the antioxidant activity of BHT and the essential oil. Over time, a decreasing and increasing trend was observed in pH and acidity, respectively, the slope of these trends was greater in the control sample. Nepeta essential oil and benzoate/sorbate significantly delayed microbial spoilage. The antimicrobial potential of the essential oil and its nanoemulsion were comparable with benzoate/sorbate activity (P > 0.05). At the end of storage, the overall-sensory scores of the sample containing the nanoemulsion were higher than the threshold-limit (>3) while in the 5th week, the control sample was introduced as unacceptable by evaluators. Nepeta nanoemulsion showed good potential to enhance the shelf-life of mayonnaise. Using essential oil in the form of nanoemulsion, not only reduced the consumption of essential oil but the bioactivity of the essential oil was protected for a longer time.

The present study aimed to investigate the physicochemical characteristics of the encapsulated roasted date-seed (180°C, 20 min) extract. Date-seed (Phoenix dactylifera L. cv Kabkab) extract was obtained using a combination of ultrasound- (25 ± 5 ºC, 15min.) and microwave- (2.30min.) assisted extraction. Phenolic-compounds of the extract were identified by HPLC. The encapsulation process was done by the freeze-drying method. Soy-protein concentrate and maltodextrin were used as wall materials (M(100): Pure Maltodextrin; S(100): Pure Soy-protein; MS(75:25): Maltodextrin: Soy-protein (75:25%); MS (50:50): Maltodextrin: Soy-protein (50:50%); MS (25:75): Maltodextrin: Soy-protein (25:75%)). Gallic-acid (536.87 mg 100 g-1dEx) and catechin (214.79 mg 100 g-1dEx) were the major phenolic and flavonoid compounds of the extract. The type of wall material had no significant effect on the moisture content and water-activity. The microparticle's bulk-density was varied from 0.232-0.178 g cm-3. The difference between M(100) and S(100) was significant. The microparticles showed a heterogeneous and irregular structure with flake- and sheet-shaped morphology. Several cracks were visible on the M(100) surface. The best encapsulation-efficiency was achieved for microparticles using a combination of maltodextrin and soy-protein (especially, MS(50.50)). While 68.88% of free-extract polyphenols were destroyed after 35 days at 35 °C, the encapsulation process caused retaining 61.79% (M(100)) to 76.69% (MS(50.50)). Overall, due to the appropriate solubility, low moisture, water-activity and the ability to preserve phenolic compounds of date-seed extract, encapsulation in maltodextrin-soy-protein (MS(50.50)) wall materials could be proposed as an efficient and cost-effective bioactive compound to preserve different food products and improve their nutritional value.

Oily cakes are susceptible to oxidative and microbial spoilage due to their relative high levels of unsaturated fatty acids and moisture content. Plant extracts have a good antimicrobial and antioxidant potential. However, bioactive compounds of these extract are unstable in processing and storage conditions. Encapsulation technique is considered as one of the best strategies to overcome this challenge. Therefore, the aim of this study was to investigate the efficacy of free and encapsulated extract of Butcher’s broom (Ruscus hyrcanus L.) leaves (0.7% w/w) in retarding physicochemical, microbial and sensory spoilage of oily cake during 45 days storage at 23±3˚C. The results show that the moisture content of treated cakes with Butcher’s broom extract was significantly higher than control ones (P < 0.05). At the end of storage, the lowest total color difference (ΔE) value was recorded for treated with encapsulated extract (9.4). The Butcher’s broom extract showed a significant antifungal and antioxidant potential. The lowest yeasts and mold counts, free fatty acid and peroxide value was obtained in cakes contained microparticles. The total sensory score of samples treated with encapsulated extract was higher than 3 (threshold acceptable limit) for around 40 days. While this time was 15 days for control samples. The shelf-life of oily cakes containing free and encapsulated was 1.8 and 2.3 times of control samples, respectively. Overall, encapsulation of Butcher’s broom extract with maltodextrin/gum arabic (50:50) is recommended to improved shelf-life of oily cake itsby protection effects against chemical and microbial degradation.

Co-encapsulation of more than one core material in a single encapsulation system may increase the bioactivity of individual components. Whey protein isolate (WPI) and Gum Arabic (GA) were used as wall material to encapsulate probiotic bacteria Lactobacillus plantarum (P) alone or in combination with phytosterol (Ph) by complex coacervation method. The liquid microcapsules WPI-P-GA and WPI-P-Ph-GA were transferred to the powder using spray and freeze-drying to produce solid microcapsules. Results showed that the cell viability of L.plantarum in both liquid and dried microcapsules (freeze and spray drying) were much better in the presence of phytosterol (WPI-P-Ph-GA) than the absence of it (WP-Ph-GA) and the viability of L.plantarum in spray-dried solid microcapsules was better in comparison to the freeze-dried microcapsules during the storage time (60 days). Encapsulation efficiency in spray dryer was significantly (p > 0.05) higher than freeze dryer. The microcapsules were characterized in terms of Size, Zeta Potential, and poly dispersity index (PDI). The particle size of WPI-GA and WPI-Ph-GA were 196.2±13.72 and 366.5±0.56 nm respectively. Electrostatic interaction and formation of coacervates were confirmed by Fourier Transform Infra-Red (FTIR) spectra. Scanning electron microscopy (SEM) analysis showed that microcapsules dried by freeze dryer had a porous morphology and did not have any particular shape but microcapsules that dried by spray dryer showed the quasi-spherical configuration and had a wrinkled surface. X-ray pattern of co-microencapsulated identified that microcapsules dried by freeze-dryer had an amorphous structure compared to spray-dried ones.

The aim of this study was to encapsulate the Barije(Ferula gummosa)essential oil (EO) in liposomal system and evaluate its physical and microbial properties.  Accordingly, nanoliposomes were produced by using specific ratios of lecithin-cholesterol by thin-film hydration-sonication method. Constitutive compounds of essential oil were identified using GC-Mass.  The physical properties of the liposomes, such as particle size, polydispersity index, zeta potential, and the efficiency of encapsulating system, were studied. Evaluation of antimicrobial properties was performed by the two methods of minimum inhibitory concentration (MIC) and disc diffusion test on E. coli O157:H7. Also, the effect of sub-inhibitory concentration of EO (sub-MIC) was evaluated before and after encapsulation against the growth of bacteria over 24 h. The most important constituents of EO were β-pinene (60.84%) and α-pinin (9.14%). The average particle size of EO loaded liposomes was in the range of 74.27 to 99.93 nm, which had a significant difference with the empty nanoliposome (138.76 nm) (p<0.05). Adding cholesterol to lecithin in a double-layered membrane of liposomes increases particle size and reduces the effectiveness of encapsulation (p<0.05). Electrostatic stability of empty liposomes was improved by adding a certain amount of cholesterol, but the zeta potential did not change significantly in cholesterol-based samples when essential oil was replaced in the liposomes (p<0.05). MIC of EO in encapsulating mode was lower in the liposomal system without cholesterol than in free mode.  This was confirmed by measuring the diameter of the bacteria's lack of growth. Nanoliposome specimens containing essential oil (60 mg lecithin) with concentration of 50 and 75% MIC significantly decreased the growth of E. coli O157:H7 compared to free essential oil (p<0.05). This research showed that nano-liposomal essential oil was successfully produced by thin layer and ultrasonic hydration method and the cholesterol-free sample in the liposomal membrane had an antimicrobial effect on E. coli O157:H7 relative to its free essential oil.