بررسی خواص ضد میکروبی و فیزیکوشیمیایی فیلم خوراکی بر پایه کازئینات سدیم حاوی عصاره گزنه

افزودن ترکیبات ضدمیکروبی طبیعی به بسته ‌بندی مواد غذایی یکی از روش های مرسوم تولید بسته ‌بندی‌های فعال است. در این پژوهش، فیلم های خوراکی کازئینات سدیم حاوی عصاره گزنه (در سه سطح 1، 3 و 5 درصد وزنی/ وزنی) تولید و خواص فیزیکی، مکانیکی، ریخت ‌شناسی و ضدمیکروبی آنها ارزیابی گردید. نتایج نشان داد اثر بازدارندگی فیلم‌های حاوی عصاره گزنه بر باکتری‌های گرم مثبت بیشتر از باکتری‌های گرم منفی بود. افزودن عصاره گزنه به فیلم‌های بر پایه کازئینات سدیم سبب افزایش درصد حلالیت در آب، نفوذپذیری به بخار آب و ضخامت شده و مقاومت کششی فیلم، درصد افزایش طول در زمان پاره شدن و همچنین شفافیت را کاهش داد. تصاویر بدست آمده از میکروسکوپ الکترونی روبشی نیز تاییدی بر نتایج بدست آمده بود. با استنباط به نتایج حاصله می‌توان نتیجه‌گیری کرد عصاره گزنه می‌تواند یک ماده ضدمیکروبی مناسب برای تولید فیلم‌های خوراکی بر پایه کازئینات سدیم باشد که با حفظ خواص فیزیکی و مکانیکی آنها، برای بسته بندی مواد غذایی مختلف بوِیژه مواد غذایی حساس به گونه‌ های باکتری گرم مثبت به کار رود.

evaluation of antimicrobial and physicochemical properties of the edible film based on sodium caseinate containing nettle extract

introduction: the spread of microbial diseases caused by food has led to extensive research in order to discover new ways to control microbial growth in food while maintaining their quality, freshness and safety.coating food with biopolymers is one of the ways to improve the organoleptic properties of products. in order to increase the positive effects of this process, appropriate plant extracts and essential oils can be used. in addition to creating a good taste, these herbal compounds mainly have antimicrobial and antioxidant properties. the inclusion of this material in the formulation of coatings is mainly to improve their antimicrobial properties. the use of food coatings have advantages such as being biodegradable, having nutritional value, preventing or postponing microbial spoilage, preventing moisture absorption or dehydration, preventing the destruction of nutritious compounds due to unwanted reactions such as oxidation and the browning reactions prevent the juice from leaving the meat and also act as a carrier of additives such as antimicrobial compounds, antioxidants, flavorings and colors. one of the biodegradable compounds that can be used to prepare films is sodium caseinate. this substance is highly soluble and can spread very quickly in an aqueous mixture and become homogenized in the presence of oil or fat. roman nettle (urtica pilulifera) is a one or two year old plant and is one of the native medicinal plants of west azerbaijan region, which has extensive therapeutic, antioxidant and antimicrobial properties. this extracts have high inhibitory activity against the growth of gram positive, gram negative bacteria; therefore, nettle extract can be used as one of the natural antioxidant and antimicrobial compounds in the packaging industry. in this research, the physical and mechanical properties of the sodium caseinate edible film containing this extract were investigated and its effectiveness in inhibiting the growth of food poisoning and contaminating agents was investigated.materials and methods: two bacterial strains of escherichia coli h7:o157 and staphylococcus aureus were selected to investigate the antimicrobial properties of the produced films. when preparing a liquid culture of bacteria, one full loop of each bacterial sample was removed and cultured under completely sterile conditions in 50 ml of moller hinton broth liquid medium, then at 37 °c and 140 150 rpm for 24 h in a machine. the process of diluting cultures using sterile distilled water until the microbial population was 1x106cfu/ml. 10 g of sodium caseinate was dissolved in 150 g of distilled water containing determined amounts of glycerol at a temperature of 80 ± 5 °c and a stirring speed of 550 rpm then nettle extract in three concentration levels 0, 1, 3 and 5 (%w/w) along with tween 80 emulsifier to the amount of 30% of the weight of the essential oil was added to the control film solution and by a thermal stirrer at a speed of 550 rpm for 1 min. 5 were uniformly distributed in the solution at a temperature of 60±5°c. the prepared solutions were poured amount of 35 ml in the glass plates. then drying the samples was 13.5 h at 40 °c. the dried films were slowly separated from the plates and stored in desiccators containing saturated magnesium nitrate solution with relative humidity of 50% and temperature of 25°c for experiments. measuring the thickness of the films solubility of the films in water measuring the transparency determining the wvp determining the mechanical properties studying the microstructure of the samples was done through sem. experiments were determined based on a completely randomized design using the factorial test. comparison of average data was done at 5% probability level based on one way anova test using mini tab version 17 software.