Food Biotechnology
Hadis Taghvatalab; Dornoush Jafarpour
Abstract
Introduction Scientific evidence is mounting that synthetic chemicals used as food additives may have harmful impacts on health and the biological system and cause many diseases and damages to the human body. Also, many consumers are concerned about the use of artificial ingredients to maintain ...
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Introduction Scientific evidence is mounting that synthetic chemicals used as food additives may have harmful impacts on health and the biological system and cause many diseases and damages to the human body. Also, many consumers are concerned about the use of artificial ingredients to maintain the quality and safety of foods. Therefore, the use of natural preservatives and food preservation methods based on natural compounds have attracted the attention of researchers. Edible films and coatings are useful materials, mainly produced from biodegradable polymers including polysaccharides (gums), proteins, and lipids, and are commonly used for the shelf life extension of foods. The primary edible films /coatings are promising alternative methods to preserve, and retard the adverse chemical reactions and microbial growth. They also can act as a carrier of antimicrobials, antioxidant substances, and other additives. Sage seed gum (SSG) is a water-soluble polysaccharide obtained from Sage (Salvia macrosiphon). It is an environmentally-friendly biodegradable material that can form high-viscosity aqueous solution and exhibit pseudoplastic behavior. Essential oils (EOs) are volatile and aromatic oily liquids extracted from various plants. Most of the EOs have antimicrobial and antioxidant activities due to their phenolic compounds, terpenes and terpenoids. A promising technique is incorporating EOs into coating solutions as active film/coating to extend the shelf life of food products. Bay leaf (Laurus nobilis) is an aromatic evergreen tree or large shrub with green, glabrous leaves. It is used as a flavoring agent and an essential ingredient in food preparation. Bay leaf has received much attention due to its antimicrobial, antioxidant, anti-inflammatory and immune system stimulating properties. Hence, the aim of the present study was to evaluate the antimicrobial and antioxidant properties of SSG coating incorporated with different concentrations of bay leaf EO (BLEO) and its nanoemulsion (BLNEO). Materials and Methods The active packaging was produced based on the gum of sage seed containing BLEO and BLNEO. After preparing the EO from bay leaves, their corresponding NEO was produced and the characterization of nanoparticles was evaluated in terms of droplet size, polydispersity index (PDI) and zeta potentials. Then, the antimicrobial and antioxidant properties of BLEO and BLNEO were compared. After that, SSG coatings were prepared with 1.5% and 3% BLEO and their corresponding NEO forms. Subsequently, the antioxidant (DPPH and ABTS) and antimicrobial (against Bacillus cereus, and Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli) properties of the produced films were investigated. Results and DiscussionGas chromatography-mass spectrometry (GC-MS) identified 1,8-Cineole and α- Terpinyl acetate as the major components of BLEO. The BLNEO exhibited a droplet size of approximately 92.4 nm and a zeta potential of -45.1 mV. In comparison to the control and SSG, it was found that the group comprising EO and NEO significantly (p<0.05) showed superior free radical scavenging capacity. SSG-3% BLNEO had the highest DPPH inhibition percentage (69.54%). According to the results, EO at the nanoscale can scavenge more free radicals than EO (p<0.05). Antimicrobial inhibition zone of different treatments against selected gram positive and gram negative bacteria showed that all bacteria were strongly inhibited after the addition of BLEO into the SSG. Moreover, data revealed that the growth of the studied pathogens was completely inhibited in a dose-dependent manner (p<0.05). SSG-BLNEO exhibited better antimicrobial activity than SSG-BLEO coating and its antimicrobial activity was significantly enhanced by increasing BLNEO concentration (p<0.05). This phenomenon is attributed to the protective role of encapsulation and the slow release of EO from the coating matrix, resulting in enhanced antimicrobial activity. Nanoemulsions, owing to their small droplet size and high surface area, offer superior efficacy compared to conventional emulsions. Consequently, the gradual release of essential oils from nanoemulsion-based edible coatings contributes to their enhanced antimicrobial performance. ConclusionThese findings suggest that the SSG-BLNEO edible active coating possesses promising applications as an antimicrobial and antioxidant agent for food packaging applications.
Masoud Najaf Najafi; Haminreza Shateri; Morteza Kashaninejad
Abstract
Introduction: It can be seen that in most studies published on low fat yogurt, the effects of fat substitutes or process changes, including the homogenization process, have been considered separately. However, process changes, especially changes in homogenization pressure, in addition to the effect on ...
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Introduction: It can be seen that in most studies published on low fat yogurt, the effects of fat substitutes or process changes, including the homogenization process, have been considered separately. However, process changes, especially changes in homogenization pressure, in addition to the effect on yogurt, has also an effective role on fat substitutes such as hydrocolloids and can affect their functional characteristics. Therefore, in order to understand the proper conditions of industrial production, it is necessary to study these changes simultaneously. Due to the importance of low fat yogurt production, the effect of konjac gum, sage seed gum, homogenization rate and fat content on pH, texture, and color of low-fat yogurt was investigated using mixture-process variable experiments and modeling the properties obtained from this experimental method. Materials and methods: To prepare low-fat yogurt, firstly, the cream of 40% fat was added to the milk with 0.05% fat, sage seed gum, and konjac gum were added according to the design treatments and calculated by Pearson square method. The preparation was then heated to 90 °C and cooled down to 45 °C. The starter was then added and incubated in oven until reaching pH = 4.6. The yogurt was cooled down and dispersed in a 100 g cups of polyethylene. Texture analyzer was used for combination of back extrusion and texture profile analysis (TPA) test. The evaluated parameters were: hardness (N), cohesiveness, springiness, gumminess (N), chewiness (N), adhesiveness and adhesiveness force. pH was measured according to AOAC official method NO. 981.12. Results and discussions: The results showed that only the effect of fat content on the 99% level was significant on the pH of the samples, while konjac, sage seed gum, and homogenization rate had no significant effect. By increasing the fat content, the pH of the samples also significantly increased. It is likely that the increase in fat content will reduce the metabolic activity of the starter bacteria and thus increase the pH of the samples. Also, when the fat content of the samples was kept constant (1.75%), increasing the konjac gum and reducing the sage seed gum when the homogeneity of the samples was between 0 and 1200 rpm, the hardness of the samples initially increased and then decreased. When both gums were added at the same level, the hardness decreased indicating the high synergistic effect of these gums at low homogeneity rates. The results of this study showed that only linear effect of fat in 99% level on the adhesiveness force of samples was significant so that by increasing the fat content, the adhesiveness force of the samples increased. Also, the results showed that with increasing the konjac gum and reducing the sage seed gum, the gumminess of the samples first increased and then decreased. The most gumminess sample was in the conditions that both gums were used at the same level, indicating the high synergistic effect of these gums on the gumminess of the samples. The results of color measurement showed that only the linear effect of sage seed gum and the interaction effects of konjac gum-sage seed gum, konjac-gum on homogenization rates of L* samples were significant, and with increasing the level of konjac gum and reducing sage seed gum, L* samples decreased, but with increasing homogenization rates, L* samples increased. In this research, minimization of the fat content and adhesiveness force and maximization of the hardness and cohesiveness was considered as optimization aims. The optimum point calculated as 0.146% konjac gum, 0.053% sage seed gum, 2.42% fat content and 12300 rpm homogenization rate. In this conditio, the responses were: pH=4.5, hardness=3.25 N, adhesiveness force=0.815 N, cohesiveness 0.258 mm and L* 85/18. As a conclusion of this investigation, it could be said that these types of models could be utilized in industries to optimizing the formulation of such product, reducing the cost and increasing the acceptance.
