مريم محمدي

This study was conducted to re-encapsulate β-carotene (BC) loaded in nanostructured lipid carriers (BC-NLCs) through entrapment within complex coacervates of Quince seed mucilage (QSM) and Chitosan (Ch), and to evaluate the stability of the developed delivery system. First, the optimal conditions for biopolymer coacervation, as well as the appropriate method and level of BC-NLCs incorporation for entrapment, were determined. Subsequently, the effects of environmental stresses (0–2% NaCl, 0–10% sucrose, pH 3.5–6.5, and heating at 65 or 75 °C) on the release of entrapped BC-NLCs were investigated. In addition, the impact of thermal processing (75–90 °C for 5 min) on the chemical stability of BC in real food matrices containing entrapped BC-NLCs was examined. Due to the gradual deprotonation and insolubilization (i.e., simple coacervation) of chitosan at higher pH values, the optimal pH could not be identified from the turbidity, electrical conductivity (EC), and zeta potential (ZP) curves of the biopolymer mixtures. Instead, it was determined to be 4.25 based on the minimum EC of the individual biopolymers. Based on turbidity, coacervation yield, and ZP data, electrostatic interactions between the biopolymers were maximized at a Ch/QSM ratio of 0.25. Performing the entrapment process by first mixing BC-NLCs with chitosan and subsequently with QSM, at a nanoparticle-to-biopolymer ratio of 0.25, resulted in the highest entrapment efficiency (88%). FTIR results revealed the involvement of electrostatic and H-bonding interactions in biopolymer coacervation, and together with X-ray diffraction data confirmed the encapsulation of BC-NLCs. SEM images showed that the biopolymeric coacervates exhibited a gel-like network structure in which BC-NLCs, rather than being located within the pores, formed composites with the coacervates, contributing to the filamentous and sheet-like structures constituting the gel network. Overall, the molecular weight of chitosan had no significant effect on the above results. The addition of EDTA (100 ppm) to BC-NLCs resulted in 95%< BC retention after exposure to environmental stresses. Adding NaCl (0.5–2%), adjusting pH above 3.5, and simultaneously applying more severe heat treatment (75 vs. 65 °C) enhanced the release of entrapped BC-NLCs due to the weakening of electrostatic interactions within the composite. Entrapment of BC-NLCs within the QSM–Ch matrix (with and/or without EDTA) improved the chemical stability of BC in processed cheese and sausage farsh, but had no effect in bread dough. The findings of this study demonstrate the potential application of novel QSM–chitosan complex coacervates for re-encapsulation, improved stability, and controlled release of nanoparticle-loaded bioactive compounds in food and pharmaceutical products.

Fruit peel, seeds and pulp are the most common by-products that are known as waste after processing. In this study, apple core protein (as a by-product from juice and pulp factories) was hydrolyzed with alcalase and pancreatin enzymes, which resulted in the production of bioactive peptides. Nowadays, bioactive peptides are of particular importance due to their key role in health promotion. The enzymatic digestion process (PH=7.4) was performed at times of (60,120,180) minutes and at concentrations of 2% w/w (enzyme to substrate ratio). Then, the physical and chemical properties and antioxidant activity were measured. For the encapsulation section, maltodextrin was used in the ratio of (2:1), (3:1) core to wall (core to maltodextrin) for encapsulation. Fortunately, the spray dryer performance was more successful and economical in this regard. Enzymatic hydrolysis of proteins has been shown to be an effective factor in increasing the antioxidant properties of proteins. In microencapsulated hydrolysates, solubility, bitterness, and oil absorption capacity were improved. The results showed that the moisture content index, powder production efficiency, antioxidant activity, flowability, wettability, and density were affected by different ratios of maltodextrin carrier. The microencapsulation process with the carrier significantly improved the functional properties and increased the physical stability of the peptides. Evaluation of the chemical structure of the spectrophotometer (FTIR) showed the occurrence of structural changes in the amide I region due to the placement within the carrier matrix. And the various signals observed in the protein structure were due to the vibration of the N-H and O-H groups. In the microencapsulated compounds, the removal of compounds associated with unpleasant aromas increased the level of desirability of the microencapsulations. The XRD profile showed a higher degree of crystallinity of the hydrolyzed sample. Microencapsulation with maltodextrin resulted in broader peaks (amorphous state).

عفونت زخم، از شایعترین عفونت‌ها و از چالش‌های دنیای امروز است که به علت وجود باکتری‌های مقاوم به چند دارو درمان آن مشکل است. استافیلوکوکوس اورئوس عامل مهمی در ایجاد عفونت زخم است. این باکتری به دلیل مقاومت بالای آنتی‌بیوتیکی و تشکیل بیوفیلم، 37 درصد از عفونت های زخم را تشکیل می دهد. لذا هدف از این پژوهش، بررسی اثرات ضدمیکروبی و ضدبیوفیلمی نانوذرات لیپیدی تیمول بر سویه‌های استافیلوکوکوس اورئوس جدا شده از عفونت زخم و اثر توکسیسیتی آن بر رده‌های سلولی HFF2 و HEK293 بوده است. مواد و روش‌ها: ابتدا سنتز حامل‌های لیپیدی نانوساختار حاوی تیمول، انجام گرفت. اندازه‌گیری میزان سایز، پتانسیل زتا و PDI نانوذرات، مقادیر MIC، MBC و بیوفیلم برای سویه‌های استافیلوکوکوس اورئوس‌های جداشده از عفونت زخم انجام و محاسبه گردید. برای بررسی میزان سمیت سلولی نانوذرات، تست MTT بر روی سلول‌های HFF2 و HEK293 انجام گرفت. نتایج: اندازه نانوذرات 87nm ، پتانسیل زتا +28.9mV و شاخص توزیع اندازه‌ی ذرات PDI=0.248 بدست آمد. مقادیر MIC نانوذرات تیمول و تیمول آزاد به ترتیب برابر با 25 – 100 ، 64 – 256 میکروگرم بر میلی‌لیتر بدست آمد. مقادیر MBC نانوذرات تیمول و تیمول آزاد بین 50 – 200 ، 128 – 512 میکروگرم بر میلی‌لیتر و IC50 نانوذرات تیمول برای سلول‌های HFF2 و HEK293 برابر با 275 و 230 میکروگرم بر میلی‌لیتر بدست آمد. نتیجه گیری: نتایج به‌دست‌آمده نشان می‌دهد که نانوذرات تیمول دارای پتانسیل به عنوان یک گزینه مناسب برای افزایش خواص ضد باکتریایی و ضد بیوفیلم است.