نشریه فرآوری و نگهداری مواد غذایی
سال پانزدهم شماره 1 (پیاپی 37، بهار 1402)

The growth of consumers' attention to the role of nutrition in health and well-being is the first driving force for the production of functional foods. In recent years, the tendency to produce and consume fortified foods has been increasing worldwide. Milk and dairy products are an important group of functional foods. Its protein, calcium, phosphorus, iron, riboflavin, and vitamins A and B12 play important roles in the human diet. Flavored dairy drinks are a major part of dairy products. Although they are considerably consumed, especially their probiotic and prebiotic types, they have a lower sales share compared to yogurt and milk. The purpose of this research was to produce a cantaloupe prebiotic dairy drink dessert. For this purpose, the formulation of this drink was examined in four treatments.

First, the dry ingredients of the formulation, including cantaloupe essential oil (0.02%), sugar (2.5%), modified corn starch (2.5%), and inulin (5%), were mixed in 100 ml of milk. After the heating and cooling processes, the cantaloupe prebiotic dairy drink dessert was produced (control sample = T0). In order to prepare the treatments, 2% Spirulina platensis for the first treatment (T1), 2% Moringa oleifera for the second treatment (T2), and a combination of 1% Spirulina platensis and 1% Moringa oleifera for the third treatment (T3) were used. The protein content was measured by the Kjeldahl method; the color by a colorimeter; the pH by a pH-meter; brix by a refractometer; and the antioxidant activity by the DPPH method. The calcium content was quantified by titration with EDTA; potassium content by a flame photometer; iron content by a spectrophotometer; and viscosity by a viscometer. The sensory properties were assessed by 10 panelists using the five-point hedonic method. The tests were examined for all the treatments on the 1st and 8th days of storage.

The results showed that T2 had the highest amounts of calcium, potassium, iron, ash, viscosity, and antioxidant activity, which had a statistically significant difference with the other treatments (p<0.05). According to the results of sensory evaluation, T2 received significantly higher scores in terms of mouthfeel, appearance, color, taste, consistency, and overall acceptance, compared to the other treatments (p<0.05).

The results showed that the best treatment in terms of nutritional value, sensory properties, and physicochemical properties, was the treatment containing 2% Moringa oleifera. Further studies are suggested for using this nutritive plant in the formulation of other food products.

The staleness of baking products is considered one of the most important causes of waste of these products. It indicates a change in the taste, flavor, appearance, and texture of products and finally reduces their consumer acceptance. The strudel is one of the well-known fermented sweet layered products in Iran. In this product, after incubating and baking the layered dough, chocolate or oil-based filling is injected into the middle of the bread by a pump, and the final product is packaged. However, this product is prone to staleness and texture hardening during the storage period; therefore, the methods that preserve the product during the storage period are able to increase the storage time of the product and its marketability. Normally, hydrocolloids are widely used as additives to modify the rheological and textural properties of baking products. The high-water holding capacity of hydrocolloids enables them to prevent the staleness of baked products during long-term storage periods.

The production steps of the fermented layered product were carried out according to the method of Sheikholeslami et al. (2018) with the necessary changes. The moisture content, water activity, specific volume, hardness, color, microbial load, and sensory properties of the top strudel were determined during storage time (32 °C for 30 days). The experiments were performed according to a completely randomized design in factorial arrangement. Minitab 16 software was used to analyze the data, and the differences between means were determined by Tukey test at p < 0.05.

Although increasing the storage time caused a significant decrease in moisture and water activity of the samples, the samples containing alginate gel had more moisture and water activity than the control sample. The specific volume of the samples containing 1.25% and 2.5% of gel was 9.45% and 18.51% higher than the sample without gel (control). The hardness of the sample containing 1.25% gel was significantly lower than other samples. In general, the hardness of the samples based on 1.25% and 2.5% of gel was 30.21% and 8.58% lower than the control sample, respectively. The use of gel in the top strudel formulation decreased the brightness index (L*) and increased the redness (a*) and yellowness (b*) of the final product. The microbial results showed that the microbial load of the samples was within the standard range. According to the results of the sensory evaluation, the sample containing 1.25% of gel received the highest scores for color and appearance, aroma, taste, and overall acceptance.

Based on the results obtained in this research, the samples containing gel had higher moisture content, water activity, specific volume, texture softness, and sensory scores than the control sample. In general, the best level of sodium alginate gel consumption for use in top strudel formulation in order to achieve the lowest level of hardness and the highest overall acceptance score is 1.25% gel.

After catching fish, various changes occur in the fish body and as a result of these changes the quality of the fish gradually decreases. This reduction in quality in fish is due to the growth and invasion of bacteria, autolysis process, lipid oxidation, physical and mechanical damage, that affects the freshness of the fish. Since freshness is one of the most important parameters in the fish market for the consumer, so the present study was conducted with the aim of evaluating the freshness and quality of fish sold to the Chabahar fish market by using a combination of sensory, chemical and microbiological methods.

In order to evaluate the freshness and quality, 30 fish belonging to 10 species including yellowfin sea bream (Acanthopagrus latus), frigate tuna (Auxis thazard), largemouth queenfish (Scomberoides commersonnianus), Indian mackerel (Rastrelliger kanagurta), shrimp scad (Alepes djedbada), tigertooth croaker (Otolithes ruber), pickhandle barracuda (Sphyraena jello), golden snapper (Lutjanus johnii), javelin grunter (Pomadasys kaakan) and goldstripe sardinella (Sardinella gibbosa) were purchased from Chabahar fish market and immediately transferred to the laboratory after icing. The quality of the studied fish was evaluated using sensory, biochemical (TVN, TMA, TBA and pH) and microbial (mesophilic and psychrophilic) methods.

According to the results, in terms of sensory evaluation, no statistically significant difference was observed between different fishes (p>0.05), but the highest scores of sensory factors were related to tigertooth croaker (Otolithes ruber) and pickhandle barracuda (Sphyraena jello) and the lowest It was related to goldstripe sardinella (Sardinella gibbosa). The results of biochemical evaluation showed that, except for pH, the highest amount of these indicators is related to Auxis thazard and Sardinella gibbosa, and there was a significant difference in the amount of TVN, TMA and TBA with other fish species (p<0.05). The bacterial counts in all samples was less than the permissible limit, but in Auxis thazard and Sardinella gibbosa, the number of mesophilic bacterial load was significantly higher than other fish (p<0.05), as well as the Also, the lowest and highest psychrophilic bacterial load was related to Otolithes ruber and Auxis thazard, which were significantly different from each other (p<0.05).

Overall, the results of this study showed that the fish sold in the Chabahar fish market are of suitable and acceptable quality, and fatty fish such as sardines are more susceptible to spoilage than low fat fish because in this species TMA with a rate of 7.48 ± 1.00 mg/100 g reached the permissible level of spoilage.

In order to reduce the use of antibiotics, additives and chemical preservatives, natural antimicrobial substances can be used in the composition of packaging. In the researches related to the production and evaluation of edible films in recent years, the use of essential oils (such as clove, cinnamon, ginger and basil essential oils) for microbial protection, delay food spoilage (chemical and microbial) and reducing food waste has a significant place. Films containing gelatin have good mechanical resistance and this substance can be used in the production of edible film due to its gel-forming properties (the presence of proline and hydroxyproline amino acids). Considering the abundance and availability of oregano in our country and considering the cheap price of gelatin, this type of film composition has no research history and can be a patent for its wide use in food.

In this research, the effect of different concentrations of oregano essential oil on gelatin was investigated and the properties of the edible film were evaluated. The independent variable includes different concentrations of oregano essential oil (0%, 1.25%, 2.5% and 3.75%) and the dependent variables include physicochemical tests (solubility, vapor permeability, thickness and turbidity), mechanical tests (elongation to the breaking point, tensile strength and Young's model), antioxidant property and antimicrobial activity of edible films. All experiments were performed in three replicates (n=3) with completely random sampling. One-way analysis of variance (ANOVA) and comparison of mean data was performed based on Duncan's multi-range test using Minitab18 software at a probability level of 0.05.

In this research, the highest tensile strength and elongation at break point was 2.5% in the treatment. In the treatments of the films, the lowest solubility and permeability were observed in the concentrations of 3.75% and 1.25% of essential oil, respectively. In all treatments, turbidity was not significant, and in essential oil concentration of 2.5%, it had the highest value among the treatments. The maximum thickness of 3.75% essential oil concentration was 0.058 mm, which was not significant in all treatments (p<0.05). Antioxidant property was significant in all treatments of edible films (p<0.05). The largest diameter of the inhibition halo in the diffusion disk method in the concentration of 3.75% essential oil was related to Staphylococcus aureus with an average of 18.26 mm. The mean halo diameter for Pseudomonas aerogenesa and Escherichia coli was reported to be 8.27 and 8.9 mm, respectively.

The results of this research showed that adding oregano essential oil to gelatin film at a concentration of 2.5%, in addition to inhibiting the growth and proliferation of bacteria, created films with sufficient strength and als it can also be used in perishable foods .

There are numerous physical, chemical, and biological hazards that can threaten and contaminate safe food. Biological factors, including bacteria involved in food spoilage and zoonotic diseases, account for a high percentage of this risk. One of the new approaches developed in food safety is designing and applying the strategy of utilizing cell structures and bioactive metabolites derived from probiotics that are known as postbiotic compounds. Teichoic acid, membrane-bound exopolysaccharides, short-chain fatty acids, bacteriocins, organic acids, and cytoplasmic enzymes are known as functional postbiotics. Due to their unique chemical structure and function, the mentioned compounds play a role in the chemical and microbial safety processes of food by absorbing and destroying chemical agents, toxin detoxifying, and inhibiting the growth and proliferation of pathogenic organisms. Among the functional mechanisms involved in the establishment of chemical safety by postbiotics, we can mention the activity of structural change, deformation, and surface absorption of some heavy metals and mycotoxins, as well as the reduction of heavy metal- and mycotoxin-induced oxidative stress responses. In regard to microbial safety, acidifying the cell cytoplasm, preventing the regulation and production of energy, inhibiting the growth of pathogenic microorganisms by forming pores in the cell membrane, causing morphological and functional changes in sensitive components such as proteins and peptides by creating acidity in the cell cytoplasm, and also stimulating the creation of oxidation pathways in bacterial cells are considered to be the main antimicrobial action mechanisms of postbiotics. Therefore, it can be acknowledged that postbiotic compounds can be used as a new approach and a promising tool to ensure safety parameters, increase the storage time of food matrices, and also formulate and produce functional foods. Technological challenges in the production of postbiotic compounds, the main mechanisms involved in establishing chemical and microbial safety, their application in food matrices, the effect of food components on their performance, and the methods of preservation and stability of postbiotics in food matrices are some of the issues discussed in this review.Due to their unique chemical structure and function, the mentioned compounds play a role in the chemical and microbial safety processes of food by absorbing and destroying chemical agents, toxin detoxifying, and inhibiting the growth and proliferation of pathogenic organisms. Among the functional mechanisms involved in the establishment of chemical safety by postbiotics, we can mention the activity of structural change, deformation, and surface absorption of some heavy metals and mycotoxins, as well as the reduction of heavy metal- and mycotoxin-induced oxidative stress responses. In regard to microbial safety, acidifying the cell cytoplasm, preventing the regulation and production of energy, inhibiting the growth of pathogenic microorganisms by forming pores in the cell membrane, causing morphological and functional changes in sensitive components such as proteins and peptides by creating acidity in the cell cytoplasm, and also stimulating the creation of oxidation pathways in bacterial cells are considered to be the main antimicrobial action mechanisms of postbiotics. Therefore, it can be acknowledged that postbiotic compounds can be used as a new approach and a promising tool to ensure safety parameters, increase the storage time of food matrices, and also formulate and produce functional foods. Technological challenges in the production of postbiotic compounds, the main mechanisms involved in establishing chemical and microbial safety, their application in food matrices, the effect of food components on their performance, and the methods of preservation and stability of postbiotics in food matrices are some of the issues discussed in this review.

Today, Pickering emulsions, as the most stable type of emulsion, have been widely accepted for use in various food, pharmaceutical, and cosmetic products. The common use of biopolymers such as proteins and polysaccharides as stabilizing or thickening agents in the formulation of these emulsion systems, due to their inherent functional characteristics, easy preparation, nutritional value, biodegradability, and biocompatibility, encourages researchers to design new hybrid Pickering stabilizers with enhanced functional properties. Therefore, in the present study, the fabrication of sodium caseinate/soy soluble polysaccharides conjugate nanoparticles and the potential of these novel emulsifiers to stabilize the Pickering emulsion was investigated.

Materials and methods:

First, sodium caseinate/soy soluble polysaccharides conjugates (NaCS/SSPS) with a protein/polysaccharide ratio of 9 to 1 were produced through the Maillard reaction using the dry heating method under optimal conditions (temperature of 60 oC and 75% relative humidity ), and after confirming the formation of covalent binding between NaCS and SSPS via attenuated total reflectance-Fourier transform infrared spectroscopy, the conjugate capability to create a stable emulsion was studied, and compared to native biopolymers. Then, to produce NaCS/SSPS conjugate nanoparticles (Pickering stabilizer), ultrasonic pulse treatment was applied (400 W- 28 minute) and two important features of particle size and their wettability were measured. In the following, the potential of Pickering emulsion formation using NaCS/SSPS conjugate nanoparticles was characterized and the stability of obtained emulsions was compared to that of untreated NaCS/SSPS conjugates.

The formation of covalent binding between NaCS and SSPS and structural changes of NaCS during conjugation reaction were detected through attenuated total reflectance-Fourier transform infrared spectroscopy. Increased physical stability against creaming was observed for emulsions stabilized by conjugates when compared with those produced by the native biopolymers. In addition, differential scanning calorimetry results showed that the thermal stability of NaCS was significantly increased by glycosylation reaction. Based on the dynamic light scattering and contact angle measurements, the ultrasonic treatment led to a significantly decreased particle size and an increase in their wettability, which allowed the creation of a high stable Pickering emulsion. The enhanced wettability of the NaCS/SSPS nanoparticles was achieved by exposing the hydrophobic sections hidden within the conjugate structure.

Owing to the successful fabrication of high stable Pickering emulsion using the hybrid nanoparticles produced by combining two techniques of conjugation and ultrasonic method, it can be suggested to employ NaCS/SSPS conjugate nanoparticles for the manufacture of Pickering emulsion delivery systems for bioactive compounds.