Food Chemistry
Mozhgan Akbari; Reza Farhoosh; M. Moeenfard
Abstract
IntroductionToday, many edible oils such as palms, corn, soybeans and sunflowers are used in food preparation. Essential oleic, linoleic and linolenic fatty acids, found abundantly in olive, sunflower and soybean oils, respectively, play an important role in maintaining health. Antioxidant compounds ...
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IntroductionToday, many edible oils such as palms, corn, soybeans and sunflowers are used in food preparation. Essential oleic, linoleic and linolenic fatty acids, found abundantly in olive, sunflower and soybean oils, respectively, play an important role in maintaining health. Antioxidant compounds are used to increase the shelf life of oils, which are classified into two groups of natural and synthetic antioxidants based on the source of production. Phenolic acids are a subset of a large group of phenolic compounds that are used as natural antioxidants in industry. Gallic acid is much stronger than protocatchuic acid due to its three hydroxyl groups. However, the presence of more than three hydroxyl groups does not seem to increase the antioxidant effect in oily systems. The position of the hydroxyl group on the aromatic ring also affects the antioxidant activity, so that the replacement of the hydroxyl group in the ortho and para position increases the antioxidant activity of phenolic acids. Methyl gallate, which is widely found in plants and polyphenolic secondary metabolites, is a natural antioxidant. Despite efforts to date, no suitable natural antioxidant has been proposed to control the thermal oxidation of oils at high temperatures. Therefore, due to the widespread use of oils in food, the thermal stability of natural antioxidants gallic acid and methyl-gallate compared to the powerful but synthetic antioxidant TBHQ, depending on the degree of satiety of the lipid system (sunflower oil and olive oil) and 80 degrees Celsius will be evaluated in this study. Material and MethodsSamples of sunflower and olive oil were purchased from local stores. All chemicals and solvents were provided by Merck and Charlot. Sunflower and olive oil were purified by column chromatography to remove natural antioxidants. Oxidation of purified sunflower oil (1 g per oil) in the presence of a concentration level of gallic acid, methyl gallate and TBHQ (1.2 μmol/g) in glass bottles. The rate of progression of oxidative reactions and the evaluation of oil quality during temperature application is possible by measuring the peroxide number. The carbonyl number is determined using 2-propanol as solvent and 2,4 decodenal as standard and absorbance at 420 nm. The effect of antioxidants (InH) on the oxidation of the test samples can be measured based on the kinetic parameters. These parameters are stability factor F, ORR oxidation rate ratio, activity A and average consumption of WInH antioxidants. Results and DiscussionThe minimum and maximum induction times are related to the control sample and the sample containing the synthetic antioxidant TBHQ, respectively, which, considering the position of the two hydroxyl groups in the para position relative to each other in the TBHQ molecule, make this antioxidant stronger. Justifies. At 80 °C and in sunflower oil, the antioxidant methyl gallate shows a more effective stability factor (F) and antioxidant activity (A), indicating greater antioxidant power than gallic acid. Similarly, F-ORR-A values in methylgalate treatment have a significant effectiveness compared to other treatments. The higher oxidative stability of olive oil against sunflower oils can be attributed to the small amounts of oleic acid and especially the small amounts of linolenic acid in olives. Stability factor (F), is significantly higher for the TBHQ antioxidant than the values obtained for the other two. This factor is affected by the induction period of antioxidants and can be expected due to the effectiveness of antioxidants in increasing the duration of the induction period. The highest value obtained for the ORR oxidation rate parameter, is related to the antioxidant gallic acid. The parameter of antioxidant activity A, in TBHQ is higher than the other two antioxidants. Measurement of carbonyl compounds resulting from the decomposition of hydroperoxides is a good measure of the rate of development of oxidative reactions. In the treatment of gallic acid and TBHQ, the changes in the carbonyl number decrease at the end of the annealing, which is probably due to the decomposition of carbonyl compounds and the production of polymer compounds. Which cannot be measured by carbonyl number test. ConclusionBetter efficacy of gallic acid compared to methyl gallate in olive oil and better efficacy of methyl gallate compared to gallic acid in sunflower oil at 80 °C show the composition of fatty acids, the nature of lipid systems and the position of antioxidants in the reaction medium. Have a great effect on improving the performance of antioxidants. Determination of oxidative stability based on carbonyl number shows similar results to peroxide number .
Food Biotechnology
S.Javad Hosseini; Mostafa Shahidi Noghabi; Hossein Zamani; Gholamhossein Zohuri; Mahboubeh Sarabi
Abstract
The essential oils usually have a good effect against undesirable microorganisms; therefore, they can be utilized as natural antimicrobial agents in food or their packaging. In this research, the antimicrobial attributes of two essential oils (Oliveria decumbens and Pistacia atlantica gum), have been ...
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The essential oils usually have a good effect against undesirable microorganisms; therefore, they can be utilized as natural antimicrobial agents in food or their packaging. In this research, the antimicrobial attributes of two essential oils (Oliveria decumbens and Pistacia atlantica gum), have been investigated before and after thermal process (200°C - 10 minutes) against bacterial and mold spoilage in bread. Also, the compounds of essential oils were detected by gas chromatography-mass spectrometry. The main compounds of the essential oil of O. decumbens were carvacrol, thymol, and elemicin before and after thermal treatment. In the case of P. atlantica gum, only one prominent peak was observed in the chromatogram, which was related to the α-pinene. For both essential oils, the MIC and MFC against Aspergillus niger were 4000 and 8000 μL/ml, respectively. In comparison, the antimicrobial effect of both essential oils against Bacillus subtilis was higher than the mold. The amount of MIC and MBC were 125 and 250 μL/ml for Oliveria decumbens and 62.5 and 125 μL/ml for Pistacia atlantica gum, respectively. The results showed that these two essential oils have a promising effect against the main microorganisms of bread spoilage. The thermal process did not significantly affect the antimicrobial activity of Pistacia atlantica gum essential oil against A. niger but significantly decreased the antimicrobial activity against B. subtilis, while in the case of antimicrobial activity of Oliveria decumbens essential oil, the results were the opposite. Considering the fact that the most spoilage agents of the bread are molds so the use of Pistacia atlantica gum essential oil is recommended as natural preservatives in products that tolerate high heat treatment, such as bread and bakery products.
Layla Zaghari; Alireza Bassiri; Somaye Rahimi; Ali Zonousi
Abstract
Intoduction: Probiotic products have been used worldwide in the last decades. They are significantly gaining popularity and their consumption is associated with increasing levels of health-consciousness. Probiotics can be defined as microbial cells that have a beneficial effect on the health and wellbeing ...
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Intoduction: Probiotic products have been used worldwide in the last decades. They are significantly gaining popularity and their consumption is associated with increasing levels of health-consciousness. Probiotics can be defined as microbial cells that have a beneficial effect on the health and wellbeing of the host. In this sense different probiotic products have appeared on the market with different formulations and applications. Bread is the major type of bakery products and a staple food in most part of the world. Despite attempts to develop functional breads containing viable microorganisms, this has not been fully developed yet because of the high temperature during baking process. Viability of probiotic bacteria in the product at the point of consumption is an important consideration for their efficacy, as they have to survive during the processing and shelf life of food. Lactobacillus reuteri which naturally occurs in the human intestine possess probiotic properties with good colonization potential. The main purpose of probiotic encapsulation is to protect cells against an unfavorable environment, include high processing temperatures and storage. The fluid bed encapsulation process consists of spraying a coating solution into a fluidized bed of solid particles. After several cycles of wetting–drying, a continuous film is formed. The main parameters affecting the process are flow-rate and pressure of the spraying liquid, composition and rheology of the coating solution, flow-rate and temperature of the fluidizing air. Double microencapsulation for probiotics by air-suspension fluidized-bed coating is a good alternative method to achieve greater resistance to high temperatures during bread baking. The aim of this study was to evaluate the survival of Lactobacillus reuteri that had been double layered using chitosan, calcium chloride and Arabic gum for microencapsulation and which had been exposed to bread baking conditions.
Materials and Methods: Pure freeze-dried Lactobacillus reuteri PT-1655 were obtained from Persian Type Culture Collection (Tehran, Iran) and were activated by inoculation in the MRS broth at 37°C for 36-48 h. The air-suspension process was performed in a Wurster coater system with a bottom spraying atomizer. In various pretests, the fluidization pressure, the atomization pressure and the spraying rate of the microencapsulation process were varied to examine their influence on process conditions, especially on the particle development. In this study, chitosan, calcium chloride and Arabic gum at concentrations (0.5, 1 and 1.5% w/v), 5% w/v and (1.5, 3 and 6% w/v) were used as second layer in double microencapsulation, respectively. Heat resistance of unencapsulated and double encapsulated microorganisms was determined by placing in an oven which was preheated to 80°C for 15 and 30 minutes. The prepared dough after adding of unencapsulated and double encapsulated bacteria was shaped into loaves of 50 g each, placed in aluminum pans, and baked in a preheated oven at 180°C for 20 min and 70 – 80% relative humidity and then cooled at room temperature. The temperature during baking process was checked by putting a thermocouple at the crumb center. The viability of bacteria at controlled conditions was measured after 1 and 24 h after baking process. Experimental data have been represented as the mean with standard deviation (SD) of different independent determinations. The significance of differences was evaluated by analysis of variance (ANOVA). Differences were considered statistically significant at p
