نشریه فناوری های جدید در صنعت غذا
سال دهم شماره 3 (پیاپی 39، بهار 1402)

Detection of oranges freezing when entering the consumer market, both from the point of view of freshness and processing, can play a very important role in the marketability of the final product.In this study, The freezing and non-freezing of orange fruit has been investigated using Fourier transform-infrared (FT-IR) spectroscopy and hyperspectral imaging First, the FT-IR spectrum of the skin of 20 healthy and freezing orange samples was obtained. Also, in the hyperspectral imaging method, images and spectra were obtained from 18 healthy and frozen orange samples using the system made by the company of the Physic Technologists. In order to further investigate the FT-IR and hyperspectral imaging data, linear discriminant analysis (LDA) was performed after applying different pre-processing methods to classify healthy and frozen oranges. The results of this research showed that after freezing, the peaks in the FT-IR spectrum, in the regions of 400 cm-1 to approximately 1500 cm-1, have undergone a fundamental change, and the intensity of these peaks has been greatly reduced. This shows the fundamental changes in orange peel samples due to freezing. The results showed that by applying the MF+SNV preprocessing method on spectroscopic data, it is possible to detect the freezing and non-freezing of orange fruit with high accuracy (accuracy for classification 92%). Moreover, the results for the hyperspectral imaging method showed that by applying the smoothing pre-processing methods, it is possible to detect the freezing and non-freezing oranges with good accuracy (accuracy for classification 75%).In general, the results showed that the FT-IR spectroscopic method has a higher accuracy and can detect freezing and non-freezing in orange peel samples. However, it is recommended to use the hyperspectral imaging to detect orange freezing if the non-destructive assessment of the sample is considered.

Adding natural antimicrobial compounds to food packaging is a common method of producing active packaging. Nettle extract has antibacterial properties against both gram-positive and gram-negative bacteria. In this study, sodium caseinate films containing nettle extract (at three levels of 1, 3 and 5 w / w) were produced and their physical, mechanical, morphological, and antimicrobial properties were evaluated. The results showed that the inhibitory effect of films containing nettle extract on gram-positive bacteria was greater than on gram-negative bacteria. The addition of nettle extract to sodium caseinate-based films increased water solubility, water vapor permeability and thickness, and reduced film tensile strength, percentage of elongation at rupture, and transparency.Scanning electron microscopy images also confirmed the results. Based on the results, it can be concluded that nettle extract can be a suitable antimicrobial agent for the production of food films based on sodium caseinate, which retains their physical and mechanical properties, for packaging various foods, especially food. Sensitive to gram-positive bacterial species.

The current work aims to compare the effect of essential oil (pure and emulsified) Nepeta glomerulosa as natural preservatives for improving the shelf life of high-fat mayonnaise during 6 weeks of storage at 35 ºC. The nanoemulsion of Nepeta glomerulosa essential oil was prepared by the ultrasound cavitation method and physical properties were determined. Soy oil was substituted by 0.5 %w/w of the Nepeta essential oil or its nanoemulsion to compare the effect of natural and chemical (BHT and sodium-benzoate/potassium-sorbate) preservatives on the chemical (pH, acidity, peroxide-value, thiobarbituric acid-reactive-substances), microbial (acid-resistant bacteria, heterofermentative lactic acid bacteria, Escherichia coli, mold and yeast content, and salmonella) and sensory properties of mayonnaise. 1,8-Cineole (26.9%), α-Pinene (7.3%), and Limonene (6.8%) were the main compounds of this essential oil. The mean droplet diameter, PDI and viscosity of Nepeta nanoemulsions were 191.95 nm, 0.255, and 1.03 cP, respectively. The addition of the essential oil (pure or emulsified) significantly improved the oxidative stability of mayonnaise. There was no significant difference between the antioxidant activity of BHT and the essential oil. Over time, a decreasing and increasing trend was observed in pH and acidity, respectively, the slope of these trends was greater in the control sample. Nepeta essential oil and benzoate/sorbate significantly delayed microbial spoilage. The antimicrobial potential of the essential oil and its nanoemulsion were comparable with benzoate/sorbate activity (P > 0.05). At the end of storage, the overall-sensory scores of the sample containing the nanoemulsion were higher than the threshold-limit (>3) while in the 5th week, the control sample was introduced as unacceptable by evaluators. Nepeta nanoemulsion showed good potential to enhance the shelf-life of mayonnaise. Using essential oil in the form of nanoemulsion, not only reduced the consumption of essential oil but the bioactivity of the essential oil was protected for a longer time.

The present study aimed to investigate the physicochemical characteristics of the encapsulated roasted date-seed (180°C, 20 min) extract. Date-seed (Phoenix dactylifera L. cv Kabkab) extract was obtained using a combination of ultrasound- (25 ± 5 ºC, 15min.) and microwave- (2.30min.) assisted extraction. Phenolic-compounds of the extract were identified by HPLC. The encapsulation process was done by the freeze-drying method. Soy-protein concentrate and maltodextrin were used as wall materials (M(100): Pure Maltodextrin; S(100): Pure Soy-protein; MS(75:25): Maltodextrin: Soy-protein (75:25%); MS (50:50): Maltodextrin: Soy-protein (50:50%); MS (25:75): Maltodextrin: Soy-protein (25:75%)). Gallic-acid (536.87 mg 100 g-1dEx) and catechin (214.79 mg 100 g-1dEx) were the major phenolic and flavonoid compounds of the extract. The type of wall material had no significant effect on the moisture content and water-activity. The microparticle's bulk-density was varied from 0.232-0.178 g cm-3. The difference between M(100) and S(100) was significant. The microparticles showed a heterogeneous and irregular structure with flake- and sheet-shaped morphology. Several cracks were visible on the M(100) surface. The best encapsulation-efficiency was achieved for microparticles using a combination of maltodextrin and soy-protein (especially, MS(50.50)). While 68.88% of free-extract polyphenols were destroyed after 35 days at 35 °C, the encapsulation process caused retaining 61.79% (M(100)) to 76.69% (MS(50.50)). Overall, due to the appropriate solubility, low moisture, water-activity and the ability to preserve phenolic compounds of date-seed extract, encapsulation in maltodextrin-soy-protein (MS(50.50)) wall materials could be proposed as an efficient and cost-effective bioactive compound to preserve different food products and improve their nutritional value.

Today, with the dramatic increase in the use of food industries in daily life, investigating the hydrodynamic behavior of different types of oils in the presence of food stabilizers has become very important. In the present study, the behavior of two drops of olive oil and rapeseed oil in a still fluid containing Tween 80 surfactant was investigated in a laboratory. In order to inject an oil drop into the fluid, an injection needle with a diameter of 0.9 mm was used, and the equivalent diameter of the drop was about 4 mm. At first, the results and calculations were validated by measuring the movement speed of the droplet limit in pure water fluid, then the effect of stabilizer concentration on the drop equivalent diameter, its limit speed and the dependence of the drag coefficient on the Reynolds number in each of the oils were investigated separately. The results showed that the presence of surfactant does not have a significant effect on the equivalent diameter of the drop, and with the increase in surfactant concentration, the equivalent diameter remains constant at about 4 mm. Also, due to the fact that all concentrations are above the critical concentration of micelles, in the presence of surfactant, the rate did not change significantly. In addition, the results related to the dependence of the drag coefficient on the dimensionless Reynolds number were reported, which showed that as the Reynolds number increases, the drag coefficient decreases gradually. In general, it can be concluded that the concentration of surfactant and the type of oil do not determine the droplet size. Also, if there is a need to reduce the hydrodynamic resistance in similar systems, increasing the Reynolds number can be a suggested solution.

In this research, the ohmic heating method was used to reduce the moisture content of white button mushroom (Agaricus bisporus). The purpose of this research is to investigate some physical and chemical characteristics of the button mushroom at the end of the ohmic process. In this research, three voltages of 60, 75, and 90 volts were used, and according to the 8 cm distance between the electrodes, 7.5, 9.37, and 11.25 volts/cm were obtained. Also, three types of steel, brass and aluminum electrodes and three concentrations of 5%, 10% and 15% ohmic solution were selected for the experiment. In order to colorimetrically measure button mushrooms, the images were scanned in color using Image J software in the Lab space, and the extracted values were expressed as percentages. Also, in order to measure chemical properties, 0.5 g of dried samples were separated and methanolic extract was prepared and properties including antioxidant activity, total phenol content, flavonoid content, vitamin C, pH and Brix were measured. The results showed that with the increase of the voltage gradient, the value of the browning index and the total color changes increased significantly. The highest and lowest values of the browning index were 244.39 (voltage gradient 11.25 V/cm-aluminum electrode) and 86.39 (voltage gradient 7.5 V/cm-steel electrode). The highest and lowest total color changes were 27.98 (aluminum electrode) and 16.01 (steel electrode) and the increase in browning index and total color changes were observed in steel, brass and aluminum electrodes, respectively. . In the chemical properties section, similar information was obtained in the parameters of antioxidant activity, total phenol content, flavonoid content, vitamin C and soluble solids; So, with the increase of the voltage gradient, the value of these parameters increased significantly. In the voltage gradient of 11.25 V/cm, the highest values have been observed.