نشریه فرآوری و نگهداری مواد غذایی
سال چهاردهم شماره 2 (پیاپی 34، تابستان 1401)

Diabetes mellitus is one of the most common metabolic disorders that affect the metabolism of carbohydrates, proteins, and fats; and is caused due to a lack of insulin secretion or reduced tissue sensitivity to insulin generating high blood sugar. Due to the side effects of using chemical drugs to treat diabetes, different plants have been used to lower blood sugar and to cure the effects of diabetes. Cake is one of the cereal products with high-consumption snack for all age groups. In this study, the possibility of producing cakes was investigated. This investigation was done by replacing some parts of wheat flour with quinoa flour and okra flour in order to use the benefits of these flours in reducing the glycaemic index in diabetics.To compensate for the negative effects of gluten reduction caused by replacing wheat flour with other flours, basil gum was used as a natural additive in cake formulations.

For this study, the nutritional properties of wheat flour, quinoa and okra flour, and cake samples were measured according to the standards. Then four cake samples (a control cake, a cake with 30% quinoa flour, a cake containing 16% okra flour, and a formulated cake consisted of 30% quinoa flour and 16% okra flour) were produced. The sample with higher nutritional value was chosen to evaluate changes in blood sugar in 10 patients with type II diabetes using the method of measuring blood sugar by a glucometer.

The result showed that the amount of protein and fiber in quinoa flour and okra flour was higher than wheat flour. The fat value in quinoa flour was more than wheat flour and okra flour. The comparison between the cake prepared from quinoa flour and okra flour with the control cake showed that the amount of fiber, ash and protein in the cake prepared with quinoa flour and okra flour was much higher than the ones in the control sample. The cake containing a combination of quinoa flour and okra flour had higher texture and sensory properties than the other samples. The result of the patients' blood glucose test during the study showed that when the cake was formulated, the patients' blood sugar response rate was much lower than when they used white bread (control).

The results of this study showed that the formulated cake with okra flour and quinoa flour can be used as a main snack for diabetics.

Strained or concentrated yoghurt is a traditional milk product that its popularity and consumption has increased during recent years due to its higher nutritional value, longer shelf life, desirable textural and sensory properties, and today it is widely produced industrially. This product can be produced from many different animal milks such as buffalo, cow, goat, ewe and camel. The milk of various animals differs in composition and therefore this factor can affect the characteristics of the final product. Identical to the other dairy products, strained yoghurt manufactured from buffalo milk has the higher quality than those produced from cow milk due to the higher total solids and fat content; but its utilization has limited because of its higher cost. Transglutaminase enzyme (TG), by createing inter- and intra-molecular cross linkages among proteins is known as an effective strategy to improve the functional properties of dairy products. TG treatment has been considered as a practical technique instead of increasing the total solids of utilized milk (by adding skim milk powder). Therefore, the aim of this study was to investigate the effect of TG enzyme treatment on physicochemical and sensory properties of strained yoghurt prepared from cow and buffalo milk mixture and to introduce the best product with the lower buffalo milk substitution (the lower of cost).

Strained yoghurt samples with different amounts of buffalo milk replacement with cow (0, 25, 50, 75 and 100%, v/v) and using TG enzyme (0 and 0.015%, w/v) were produced and 10 experimental treatments evaluated for physicochemical (pH, acidity (% lactic acid), syneresis (%) and dry matter (%)) and sensory properties (texture, colour, odour and flavour) during 21 days of storage (1, 7, 14 and 21 days) under refrigeration conditions. The obtained mean values were analyzed using a random factorial design and compared by Duncan test at 5% level.

The results showed that increasing the substitution amount of buffalo milk with cow milk caused a significant increase in acidity and dry matter while it expressively reduced the pH and syneresis of yoghurt samples (p<0.0001). Also, with increasing the TG enzyme concentration, the amount of acidity and syneresis decreased and the pH increased significantly (p<0.0001), but this variable had no significant effect on dry matter (p>0.005). Over time, the pH decreased significantly and its initial value of 4.11 at the first day of storage reached to 3.98 at the end of 21 days of storage. The initial values of acidity, dry matter and syneresis as 0.98%, 20.69% and 4.45% increased till the end of storage and reached to 1.23%, 22.16% and 10.35%, respectively. In terms of sensory acceptability, increasing the concentration of enzyme caused a significant increase in texture score of the samples (p<0.0001), while the enzyme had no significant effect on other sensory scores of the samples. With increasing the mixing rate of buffalo milk, the texture, colour and flavour scores of the samples increased significantly (p<0.0001) and the aroma score decreased (p<0.0001). Furthermore, during the storage period, the sensory properties of the samples decreased significantly (p<0.0001).

According to the results of this study, by replacing 75% of buffalo milk with cow milk and using transglutaminase enzyme treatment (0.015%), it is possible to produce a strained yoghurt with suitable quality characteristics.

Garlic extract, due to its high volatility and its effects on organoleptic properties, has limitations for direct use in food products, and therefore it is better to encapsulate it in one of the different methods and then use it in food formulations. In recent years, many methods have been used to encapsulate bioactive compounds in the food industry. Nanocapsulation can highly protect the essential oils against degradation or oxidation and may increase dispersibility in aqueous media, reduce adverse interaction with food components, and it generally do not affect antimicrobial activity of essential oils. Water-in-oil emulsions are used to encapsulate hydrophilic bioactive compounds, and the number of studies conducted on this type of emulsion is less than that of oil-in-water nanoemulsions. In this research, it has been tried to surrounding garlic extract by surfactant and forms a water in oil nanoemulsion and its physicochemical and antimicrobial properties are measured in order to be used in suitable food formulations.

In this study, nanoemulsions containing garlic extract were produced by high energy method (ultrasound bath) and the effect of different percentages of the extract on droplet size, antimicrobial properties, release kinetics, and viscosity were investigated. Encapsulation efficiency was determined by comparing the total area under the peaks of the nanoemulsions and not emulsified mixture headspace in gas chromatography. The release of volatile compounds of garlic oil was recorded during storage time by gas chromatography. Microdilution method was used to determine the minimum inhibitory concentration and the minimum bactericidal concentration. TGA and FT-IR were also used to evaluate the thermal resistance and to study the functional groups and to confirm the presence of the compounds used in the formulation of the prepared nanoemulsions, respectively.

Drop size varied from 62 to 302 nm for nanoemulsions based on volume fraction. Microbial results showed that water-in-oil nanoemulsions in high concentrations of garlic extract had antimicrobial properties and a stronger effect against gram-positive bacteria. In general, in all nano-emulsions, with increasing the volume fraction (percentage of garlic extract) from 5 to 25 %, the viscosity increased from 50 to 150 cp. Examination of viscosity changes at different temperatures showed that the activation energies for samples with different volume fractions (garlic extract) were not significantly different. Also, the release rate of volatiles increases with increasing volume fraction in nanoemulsion formulations and storage temperature.Keywords: Nanoemulsion, Garlic extract, Release kinetics, Encapsulation efficiency, Antimicrobial properties

In recent years, consumers, in addition to considering the nutritional characteristics that are normally a desired food, also pay special attention to the health characteristics of the product. Today, probiotic juices have not received much attention in the industry and have little research history. Therefore, choosing apple and cherry juices as a high pH range can be a model for other juices.

In this study, the effect of 5 variables including fruit type (apple, cherry), inulin, type of probiotic microorganisms (Lactobacillus acidophilus and Lactobacillus casei) and probiotic addition method (encapsulated and free) and storage time (1, 7, 14 and 21 days) were investigated). Some physicochemical properties of juices (turbidity, viscosity, total sugar and vitamin C) were studied. The D-Optimal response surface methodology with incomplete factorial was used to design the experiment and its analysis was performed with SAS 4.5 software.

Analysis of variance at 5% level of significance showed that except for turbidity, other independent variables had significant effects (p < 0.05) on dependent variables in this study. In the microorganisms of cherry encapsulation, the amount of turbidity is constant (approximately 4) and in free cells this amount is reduced (1.5). In apple fruit, the amount of turbidity is constant in encapsulated and free (2.8). The viscosity results showed that apple juice has a minimum viscosity (1.25) and cherry juice has a high viscosity (1.32), which depends on the type of fruit composition and its formulation. Also, the results of total sugar showed that apples have the highest percentage of sugar (10.2) and cherries have the lowest percentage of sugar (4.1). Within a month, these values were higher in the encapsulation than in the free, which was due to less fermentation by microbes. The vitamin C chart shows that apples had the lowest amount (4%) and cherries had the highest amount (18%). Encapsulated and free microbes had little effect on vitamin C.

The results of this study showed that synbiotic juice can be introduced to the market as a profitable new product with a maximum expiration time of one month according to physicochemical analysis. In addition, samples containing encapsulated microorganisms have better storage time and organoleptic properties than others. Also, in acidic fruits, this shelf life is reduced, which from the twenty-first day onwards, the physicochemical analysis of the juice changes significantly and becomes unusable.

Proteins are sensitive to environmental stresses, which limits their nutritional applications. Millard reaction leads to increases the functional and biological properties of proteins.Whey protein isolate has a wide range of applications in the food industry, but is sensitive to to the certain environmental conditions and its functional properties are reduced. Inulin is a water-soluble polysaccharide widely used in the food and pharmaceutical industries.The aim of the present study was to prepare and compare the mixture and conjugate of whey protein isolate-inulin, different weight ratios of protein-polysaccharide (1:1, 1:2 and 2:1) and investigate their functional properties.

Glycation via Maillard reaction (MR) done at 60 ◦C and a relative humidity of 79%, during 24 h. In this regard, polyacrylamide gel electrophoresis (SDS-PAGE), Fourier transform infrared spectroscopy (FT-IR) was performed to confirm the Millard reaction, and also evaluated DPPH free radical scavenging activity, (DSC), emulsifying activity index and emulsion stability index as well as viscosity.

The results of SDS-PAGE patterns and FT-IR validated the occurrence of the Maillard reaction between whey protein isolate and inulin. Also, the results indicated that the whey protein isolate and inulin conjugates have better functional properties than natural proteins and mixture of the whey protein isolate and inulin. Whey protein isolate - inulin conjugates at ratio of 2:1 showed higher emulsifying activity index, emulsion stability index and antioxidant activity, whereas the emulsions formed by conjugated whey protein isolate - inulin at ratio of 1:2 showed the highest viscosity.

Whey protein isolate glycation via Maillard reaction improve the thermal stability, antioxidant activity and emulsion stability of samples. The Maillard reaction is an effective process of improving the functional properties of proteins, so It causes the widespread use of whey protein isolate in food industry. The Maillard reaction conjugates of whey protein isolate and inulin have been used in food products such as mayonnaise and salads dressing, dairy products and diet products.

Whey protein isolate glycation via Maillard reaction improve the thermal stability, antioxidant activity and emulsion stability of samples. The Maillard reaction is an effective process of improving the functional properties of proteins, so It causes the widespread use of whey protein isolate in food industry. The Maillard reaction conjugates of whey protein isolate and inulin have been used in food products such as mayonnaise and salads dressing, dairy products and diet products.

Technological advances in the food industry have led to development of various processing methods to increase the shelf life of fruit and products divided from fruit to ensure access to them during the year, even for seasonal fruits. The conventional heating method causes undesirable changes in the final product such as color changes, unpleasant taste and degradation of Ascorbic acid. The Aim of this study was to investigate the effect of microwave processing as an alternative the conventional method on the physicochemical properties of orange juice.

All chemicals used in this study were purchased with High-Purity from reputable companies. Jaffa orange was purchased from the local market in Gorgan (a city in north of Iran). Effect of continuous flow microwave treatment (MW) on physicochemical and qualitative properties of orange juice including vitamin C, browning index (BI), turbidity, cloud value, soluble solids (Brix), acidity, viscosity and pH of orange juice (com up time “CUT” phase) was evaluated. All indices were monitored until the end of the Holding phase (inactivation of PME to 90%).

Results of the experiments showed that various temperature treatments at full power microwave (900 W) caused a slight decrease in pH and a slight increase in acidity and Brix during the CUT phase (p <0.05). But no significant change was observed in these parameters at Holding phase (p> 0.05). All spectrophotometric parameters of juice including browning index, turbidity and cloud value was raised after exiting from microwave (CUT phase) with increasing in temperature (p <0.05). These parameters increased slowly until the end of the Holding phase. Increasing in temperature to the CUT phase; the viscosity was decreased significantly at high temperatures (70 and 80 ° C) and no significant change was observed after the CUT phase. Vitamin C raised with increasing in temperature in all thermal treatments. The degradation rate was high (at 80 ° C) at the Holding phase. Different thermal treatments caused 70 to 80% decline in PME activity during CUT phase.

Continuous flow microwave heating is an emerging technology that can potentially be used to heating of liquid foods. Microwave aid processing of orange juice is an effective method to inactivating of PME enzyme, through significant increasing in degradation rate. The results showed that increasing in temperature, enhanced the browning index, turbidity and cloud value. Different treatments had no significant effect on the Brix, acidity and pH in the holding phase. On the other hand, increasing in temperature, enhanced the rate of vitamin C and PME degradation.

Nitrate is the most important source of nitrogen in plants. The market demand has led to the use of chemical fertilizers which results in the increase of nitrate composition of the soil. Most plant organs are able to regenerate nitrate but the increase of this element in the plant causes accumulation in its parts. Excess nitrate intake in the body through food products can cause health hazards. Tomatoes and pomegranates are two products that in addition to being eaten fresh, are also used as paste, dried and juice. Therefore do to the importance of nitrate and nitrite content in the safety of these products, measurement of nitrate in these products and the effect of heating and drying processes was investigated in this study.

Tomato and pomegranate samples were gathered from the fields and gardens of Marvdasht, Arsenjan, Shiraz and Fasa in the Fars province. Nitrate levels were determined by HPLC. The correlation between nitrate content and sample size, pH and moisture content was also investigated. In the next step, the processes of cooking and preparing paste, drying and dehydration were performed on the samples and the residual nitrate concentration in the samples was re-measured.

The results showed that the highest amount of nitrate content in tomatoes were from Kazeroon and Shiraz cities with the amount of 27.7 and 25 kg/mg wet weight. A correlation was observed between nitrate and pH in tomatoes. The highest concentration of nitrate concentration was in pomegranate fruit related to samples of Fasa and Shiraz regions with 6.1 and 5.8 mg/kg weight wet, respectively. There was a correlation between the volumes of pomegranate samples with nitrate. The amount of nitrate in tomato juice sample was higher than dried tomato sample, and tomato paste had the lowest amount of nitrate. There was no significant difference between the amount of nitrate in pomegranate juice and raw pomegranate, while the amount of nitrate in pomegranate paste and dried pomegranate was decreased.

According to the world standards, the nitrate content in all samples gathered in the Fars province were not high and in the safe limits 120 mg/kg wet weight. It was also determined that the nitrate content in the processed samples were much lower than the raw samples. Nitrate was decreased up to 86 percent in samples that were heated, such as tomato paste and pomegranate paste, while in the tomato juice samples nitrate did not show much decrease (37 percent) due to the solubility of nitrate in water. Proper farm management in fertilizing and proper processing of these products can help reduce nitrate content in products.

Patulin is a mycotoxin produced by various species of fungi, especially Penicillium and Aspergillus. Most of these fungi grow on rotten fruits, especially apples, pears, grapes and peaches. The global standard for the presence of this substance in apple juice and other juices is about 50 ppb. Measuring the amount of this mycotoxin is important because patulin has a wide range of toxicities, including carcinogens that can have adverse health effects. Due to the stability of the molecule, a significant amount of patulin is still present in apple products. Research on the healing properties of apples and their products has increased due to its healing properties and increasing popularity among consumers. Meanwhile, concerns about the contamination of apples with patulin toxin have led to increased monitoring of crop production and the use of appropriate methods to reduce this toxin. The aim of this study was to investigate the reduction of patulin in apple juice by cheap mineral soil of Tonsil.

In order to reduce the amount of patulin in the samples, tonsil clay with amounts of 1, 2 and 5 g/l was added to apple juice at 5, 15 and 30 minutes at room temperature to reduce the amount of toxin. Patulin amount was examined by HPLC method.

The results showed that tonsil clay as an adsorbent with high adsorption capacity reduces the amount of patulin well. With increasing the concentration of tonsil clay and its effect time, the amount of patulin in apple juice decreases significantly and reaches close to zero. The results of using tonsil clay with values of 1, 2 and 5 g/l with impact times of 5, 15 and 30 minutes show that using the lowest amount of tonsils (1 g/l) with the lowest impact time (5 minutes) patulin is reduced to less than half.

After performing the mentioned experiments and reviewing the result obtained from the HPLC device, we conclude that the tonsil clay has the ability to absorb the patulin of apple juice and its ability should be increased according to the amount and duration of use. In general, the amount of patulin in apple juice can be easily and accurately determined using the method mentioned in this report. This method is recommended in juice factories to reduce the amount of patulin and show the current quality of apple juice in terms of the amount of patulin.

The presence of antibiotic-resistant genes in local cheeses is not desirable due to the risk of gene migration, increased resistance to antibiotics in consumers, and therefore the effectiveness of related drugs during the treatment period. Recently, the studies showed that the demand of local cheeses made from raw milk have increased. However, there is concern that consumption of these cheeses could increase the risk of antibiotic-resistant genes transfer through bacteria especially Enterococcus spp to consumers. Of course, traditional fermented products may contain intrinsic microbial flora with unique useful properties, including the production of antimicrobial metabolites and resistance to phages, which is very important for the dairy industry. The ability of bacteriocin production by the microbial flora that responsible for fermentation of cheeses made from raw milk is very important because it prevents the growth of pathogenic bacteria. Therefore, the aims of this study were the evaluation of the presence of antibiotic-resistant microbial flora of local cheeses made from raw milk and the investigation of the useful properties such as the presence of its antimicrobial metabolites.

Cheese made from raw milk was produced based on a traditional recipe. For isolation of Enterococcus spp., KAA agar was used, followed by incubation for 48 h at 37°C. The serial dilution of cheese was carried out until the final dilution of 10-8 in ringer. For isolation of Enterococcus spp., a 100 µl of diluted sample was cultured on KAA agar, then incubated for 48 h under anaerobic conditions at 37°C. The catalase-negative and Gram-positive isolates were phenotypically distinguished at genus level using physiological tests )growth at salt concentrations 6.5% and 18%, pH 9.6 and 4.4, temperatures 10°C and 45°C and gas production. After phenotypic detection of isolates at genus level, culture-dependent characterization through PCR and subsequently sequencing was carried out. DNA extracted from cheese was proliferated and sequenced by NGS technique. The metagenomics data were processed for phage resistance, antibiotic resistance, bacteriocin and antioxidant components production. Furthermore, antibiotic resistance of isolates and antimicrobial properties of cell free supernatant (CFS) from cheese were evaluated.

A total of 20 bacteria were isolated from cheese and molecularly identified as Enterococcus malodoratous (60%), Enterococcus faecalis (5%), Enterococcus duran (5%), Enterococcus spp. (30%). Also, the metagenomic analysis showed that Enterococcal community of cheese include Enterococcus malodoratous (72%), Enterococcus faecalis (6%), Enterococcus italicus (13%), Enterococcus spp. (10%) and its microbiome is resistance to ‌-antibiotics ‌and bacteriophages and has the production potential of antioxidant compounds and antimicrobial compounds such as plantaricin. Moreover, laboratory tests confirmed ‌‌antibiotics resistance and antimicrobial properties of isolates.

This study showed that some local cheeses can be responsible for transferring antibiotic-resistant genes to humans and consumption of these cheeses should be limited.

In this study, the rheologhcal properties of wood cellulose nanofiber (W-CNF), bacteria derived cellulose nanofiber (B-CNF) gels and chitin (ChNF) nanofiber gel were evaluated and copared.

Cellulose has long been used in the form of wood and plant fibers as a source of energy, building and clothing materials. Bacterial cellulose due to its high purity and much more suitable properties than plant cellulose, Has been used as a suitable biomaterial for various purposes, such as paper, electronics, food, acoustics, biomedicine, tissue engineering and medicine industries. The properties of nanocells (such as mechanical properties, thin film properties, viscosity, etc.) make it an interesting material for many applications. Chitin is the most abundant natural polysaccharide after cellulose and its most important source is the marine crustaceans and the cell wall of some plants.

In this study each nanogel was prepared in 2 concentrations of 0.5 wt% and 1 wt% for rheological study. Rheological properties such as oscillatory strain sweep, oscillatory strain control and shear rate sweep were measured using a rotational rheometer. The flow behavior data were fitted with rheological models. Nano paper was prepared to study on morphological and chemical properties and SEM, FTIR and AFM tests were performed on them.

SEM showed that the average diameter of MCNF, BCNF and ChNF obtained were 35, 48 and 26 nm, respectively. The AFM pictures showed W-CNF had higher height difference resulting from the cellulosic strands arrangement and non-uniformity of them. The B-CNF had lower height difference, because of its more uniform surface and structure Nano-fibers have network structures. Most of the characteristic peaks of the BCNF, WCNF, and ChNF were observed in the same positions. The 1% concentration of bacterial cellulose had higher storage modulus than other nanogels. Whit increasing in nanogels concentration, their texture strength was increased and made strong gel. Nanogels had Intertwined and strong texture and at low frequencies they had elastic behavior but their matrix texture loses its strength at high frequencies and becomes two-phase and their behavior changed to viscous state. The viscosity of nanogels decreased uniformly with increasing shear rate. When the concentration of nanogeles increased, their viscosity was increased. All nanogels had Pseudoplastic and non-Newtonian behavior. When the concentration of nanogeles increased, the amount of hysteresis increased. Bacterial cellulose nanogels had higher area of hysteresis. The shear thinning behavior can be due to the weak bonds breakdown between particles.