Impact of ultrasonication and blanching as a pre-treatment on quality parameter of dried and rehydrated bitter gourd

Vegetables are owed to the restriction of seasonal availability and regional abundance; it becomes essential that vegetables are preserved safely during the off-season. These existing demands look for dried products with high nutritional and organoleptic properties similar to fresh products. This study aimed to investigate the effect of ultrasonication and blanching before hot air drying on the quality attributes of bitter gourd (Momordica charantia). Dried samples were rehydrated to find the efficiency of pre-treatment and physicochemical properties. M. charantia slices were pre-treated with ultrasonication and blanched and dried at two different temperatures, 50 °C and 60 °C. M. charantia pre-treated using ultrasonication and dried at 60 °C reduces the drying time to 50% and rehydration time to 40% compared to untreated samples. Physico-chemical analysis of ultrasonicated samples revealed to have better retention of moisture (dried - 3.6%, rehydrated - 88%), Colour ΔE (dried - 9.07, rehydrated - 1.6), ascorbic acid (dried - 513, rehydrated - 310 mg/100 g), phenol (dried - 302, rehydrated - 231 GAE mg/100 g) and β-carotene (dried - 68 µg/100 g, rehydrated - 39 µg/100 g) compared to blanching.

A study into how thickness, infrared intensity, and airflow affect drying kinetics, modeling, activation energy, and quality attributes of apple slices using infrared dryer

Drying is a widely recognized process that reduces the need for storage and shipping weight, keeps free water out of the product, and prolongs its shelf life. An infrared dryer was designed to dry apples under different drying conditions. Apple slices of 6-, 4-, and 2-mm thicknesses were dried at intensities 0.130, 0.225, and 0.341 W/cm2 and airflow 1.0, 0.5, and 1.5 m/s. The dehydrating period was prolonged with higher airflow and shortened with higher infrared intensity (IR). The shortest dehydrating period was verified by 190 min at 0.341 W/cm2, 0.5 m/s under 2 mm thickness. Increasing the sample thickness from 2 to 4 mm and then to 6 mm resulted in an 84% and 192% increase in drying time, respectively. Dehydrated apples had water activity values ranging from 0.30 to 0.40. The shrinkage ratio increased with an increase in infrared radiation intensity. However, it decreased with an increase in air velocity, while the rehydration ratio decreased with an increase in radiation intensity and increased with an increase in air velocity. Regarding total color change, apple slice thickness was a major factor. The effective diffusivities varied between 2.6 and 9.0 𝗑10-10 m2/s under different drying conditions. The dehydrating curves of apples were best described by the model developed by Midilli et al.

Freeze-dried persimmon peel: A potential ingredient for functional ice cream

The peels are considered part of waste products, which are generally discarded. The use of persimmon peel is associated with its phenolic content, dietary fibers, minerals, and pectins. The main objective of this study was to evaluate changes in antioxidant activity, total phenolic contents (TPC), and color parameters of persimmon peels after freeze drying (-85 °C for 24h), vacuum oven drying (45 °C for 12h), oven drying (50 °C for 12h) and microwave oven drying treatment (900W for 10s). In the next step, the functional ice cream was prepared and studied by adding dried persimmon peel powder (DPPP). Various properties of the resulting ice cream at 4 levels of DPPP addition were investigated. The results showed that the highest value of L*,a*,and b* parameters were in the freeze-dried sample. There was a significant difference in the TPC of samples that dried by different methods (p < 0.05). The highest amount of TPC was observed in the freeze-dried sample (673 ± 2.0 mgGAE/100g) and the lowest one was observed in the oven-dried sample (352 ± 0.5 mgGAE/100g). The highest value for IC50 (concentration of the antioxidant compound that is necessary for the DPPH radical concentration to reach 50 % of the initial value) was in the sample dried in the oven, following the vacuum oven, microwave, and the lowest value was in the freeze-dried sample. DPPP produced by the freeze-drying method was applied in ice cream formulation at different levels (0-3 %wt.). By increasing the amount of DPPP from 0 to 3 %, the overrun and L* decreased and a*, b*, hardness, and melting resistance of ice cream increased significantly (p < 0.05). Based on our findings, DPPP has the potential to be applied as an added-value ingredient in the ice cream industry to improve the functional characteristics of its products.

Oyster mushroom drying in tray dryer: Parameter optimization using response surface methodology, drying kinetics, and characterization

In this study, the drying of oyster mushrooms (P. ostreatus) in a tray dryer was optimized. The parameters used to optimize the drying process were drying temperature, airspeed, mass loading, and moisture content. Its drying kinetics were investigated at the optimum drying parameters. A quadratic equation was obtained to predict the moisture content of mushrooms at the given drying temperature, airspeed, and mass loading, and it was validated against experimental results. A minimum moisture content (9.99 wt%) was obtained at the optimum conditions of 60 °C, 3 m/s airspeed, and mass loading of 200 g using a tray dryer. Proximate analysis, shelf-life analysis, inorganic elemental analysis, and functional group analysis were done as a characterization method for mushrooms after drying at the optimum drying conditions. About 27.8 wt% protein and 50.2 wt% carbohydrates were found in proximate results. Besides, potassium and sodium were the dominant elements as estimated by spectrophotometry analysis. The induction period (IP) of dried mushrooms at room temperature is 3520:47 (hour: minute) from the oxidation stability analysis, and the water activity of dried mushrooms was found to be 0.36. The drying kinetics of oyster mushrooms were studied at various temperatures (50-75 °C), optimum airspeed (3 m/s), and mass loading (200 g). The best-fit model describing the mushrooms drying kinetics was found to be Midilli et al., with the lowest RMSE (0.008749), X2 (0.0014), and the highest R2(0.9993) values. The kinetic triplet activation energy, effective diffusivity, and diffusivity constant (Ea, Deff, D0) for oyster mushrooms drying were determined and found to lay in the general range for foodstuffs. The value of Deff results lies within the range of 10-8 to 10-12 m2/s, with Ea of 15.32 kJ/mol and D0 value 2.263 × 10-6 m2/s.

Impact of electrolyzed water as pre-treatments on drying properties and total colour difference of fresh-cut 'Tommy Atkins' mangoes

Mango fruits are a rich source of nutrients, however, due to their perishability and seasonality, minimal processing and drying offer the potential ensure a shelf stable and safe product. The use of sodium metabisulphite (SMB) as pre-treatment in the dried fruit industry has been widely adopted, but sulphite residue remains a health public concern. Therefore, this study investigated the effects of alkaline and acidic electrolyzed water (AIEW and AEW, mg/mL) as alternative pre-treatments to SMB (1% w/w) for 'Tommy Atkins' mango slices prior to hot air drying at 60 °C. Fresh-cut and untreated samples were used as a control. During the drying process the weight of the slices were monitored every 60 min for 10 h, which was used to calculate moisture ratio (MR), drying rate (DR), and the experimental data of the samples were subjected to eight thin layer models. Colour parameters (L*, a*, and b*) were measured, and use to determine colour intensity (C*), hue angle (h°), and total colour difference (TCD) before and after drying. Based on measured weight, continuous decline in MR was recorded for all dried mango slices over the drying time irrespective on treatment. Out of the eight applied thin layer models Henderson & Pabis and Logarithmic were the best appropriate models describing and predicting the drying behavior of 'Tommy Atkins' mangoes (R2 = 0.94, RMSE ≥ 0.0006). Samples treated with AEW treated samples had lowest L*, h°, and TCD values (p < 0.05). No significant different were found in h° values amongst all pre-treated and dried samples (p > 0.05), but these samples were significantly different from dried untreated (control) and fresh samples (p < 0.05). Pre-treatments maintained the visual quality of dried 'Tommy Atkins' mango slices; SMB > AIEW > AEW > untreated (control). This study provided science-based evidence for the application of acidic and alkaline electrolyzed water as an alternative pre-treatment to sodium metabisulphite for the drying of 'Tommy Atkins' mango.

Effects of gradually increasing drying temperatures on energy aspects, fatty acids, chemical composition, and in vitro ruminal fermentation of acorn

Acorns are commonly used to meet energy, protein, and mineral needs of livestock in various parts of the world. However, since acorns have quite a high moisture content at harvest, they should be stored as dried to prevent loss of nutrients and spoilage throughout storage periods. The aim of this study is to determine the drying kinetics, color, energy aspects, crude protein, crude ash, crude oil, fatty acid composition, ADF, NDF, condensed tannin, and mineral composition properties of acorns dried at gradually increasing drying temperatures. Drying processes were carried out in an air-convective dryer at temperatures of 40, 60, 80, 100, and 120 °C. The Logistic model was identified as the best model for describing current drying conditions. Increasing drying temperatures reduced L* (lightness) values and increased thermal efficiency and effective moisture diffusion values. In terms of energy efficiency, the best outcomes were achieved at 80 °C and 120 °C drying temperatures. Drying temperatures had highly significant effects on nutritional traits of acorn samples. Increasing drying temperatures increased fiber content, gas-methane production, and energy values and reduced crude protein and oil contents. Some minerals decreased and some others increased with increasing drying temperatures. Increasing drying temperatures caused slight changes in fatty acid compositions. In terms of animal drying and feeding characteristics, it was determined that a drying temperature of 80 °C was ideal for acorn drying.

Impact of ultrasonication applications on color profile of foods

Food color is a feature that provides preliminary information about their preference or consumption. There are dominant pigments that determine the color of each food; the most important pigments are anthocyanins (red-purple color), chlorophylls (green color), carotenoids (yellow-orange color), and betalains (red color). These pigments can be easily affected by temperature, light, oxygen, or pH, thereby altering their properties. Therefore, while processing, it is necessary to prevent the deterioration of these pigments to the maximum possible extent. Ultrasonication, which is one of the emerging non-thermal methods, has multidimensional applications in the food industry. The present review collates information on various aspects of ultrasonication technology, its mechanism of action, influencing factors, and the competence of different ultrasonication applications (drying, irradiation, extraction, pasteurization, cooking, tempering, etc.) in preserving the color of food. It was concluded that ultrasonication treatments provide low-temperature processing at a short time, which positively influences the color properties. However, selecting optimum ultrasonic processing conditions (frequency, power, time, etc.) is crucial for each food to obtain the best color. The key challenges and limitations of the technique and possible future applications are also covered in the paper, serving as a touchstone for further research in this area.

Drying Kinetics and Chemical Properties of Mango

Four mango fruit varieties of average slice thickness 0.6 cm and slice area 10 cm2 were dried using a mechanical dryer at varied temperatures, 55°C, 65°C, and 75°C. In general, the moisture content (MC) for all samples analyzed decreased with increasing drying time. Palmer and Haden varieties recorded the lowest MCs of 8.7% (w.b.) and 9.3% (w.b.), respectively, when dried for 14 h at 65°C. Palmer variety with the highest initial MC of 87.2% (w.b.) recorded a low final MC of 8.7% (w.b.) when dried for 14 h at 55°C. Moisture ratio decreased from 1.00 to 0.13, 1.00 to 0.12, 1.00 to 0.12, and 1.00 to 0.10 at 55°C for Kent, Keitt, Haden, and Palmer varieties, respectively. Kent, Keitt, Haden, and Palmer varieties recorded effective moisture diffusivity values of $5.90\times {10}^{–7}$ , $6.40\times {10}^{-7}$ , $6.57\times {10}^{-7}$ , and $7.33\times {10}^{-7}{\text{m}}^2/\text{s}$ , respectively. Vitamin C content of 158.34 mg/100 g recorded for Palmer was highest compared to the other varieties. Activation energy values of samples analyzed were between 19.90 and 25.50 kJ/mol for the drying temperature range. The activation energy recorded by Haden variety was highest compared to the rest. Also, twelve mathematical models were analyzed in predicting the moisture ratio of mango fruit slices during thin layer drying. The results showed that the Midilli, Page, Wang and Singh, and Logarithmic models exhibited supremacy in predicting drying behavior compared to the other eight models.

Effects of Hot Air Drying on Drying Kinetics and Anthocyanin Degradation of Blood-Flesh Peach

The purpose of this study was to explore the drying kinetics, effective moisture diffusivity, activation energy, color variation, and the thermal degradation properties of anthocyanins of blood-flesh peach under hot air drying for the first time. The results showed that the hot air-drying process of blood-flesh peach belongs to reduced-speed drying. The Page model could accurately predict the change of moisture ratio of blood-flesh peach. The effective moisture diffusivity during hot air drying of blood-flesh peach was in the range between 1.62 × 10⁻¹⁰ and 2.84 × 10⁻¹⁰ m²/s, and the activation energy was 25.90 kJ/mol. Fresh samples had the highest content (44.61 ± 4.76 mg/100 g) of total monomeric anthocyanins, and it decreased with the increase of drying temperature. Cyanidin-3-O-glucoside and delphinidin-3-O-galactoside were the main anthocyanins of blood-flesh peach as identified and quantified by UPLC-QqQ-MS. Interestingly, during the drying process, the content of cyanidin-3-O-glucoside increased at the beginning, and then decreased. However, the content of delphinidin-3-O-galactoside kept decreasing during the whole drying process. Considering the drying efficiency, fruit color and quality, 70 °C would be a suitable temperature for drying blood-flesh peach. This research will provide beneficial information for understanding the anthocyanin degradation of blood-flesh peach during drying, and guide the production of high-quality dried products.

The effect of high-power ultrasound pretreatment on drying efficiency and bioactive compounds of chokeberry (Aronia melanocarpa L.)

Chokeberry (aronia) fruit is a rich source of bioactive compounds with various health benefits. However, it has a limited shelf life and a firm (tight) structure that makes it difficult for moisture transfer during drying. Therefore, the aim of the study is to investigate the effects of high-power ultrasound pretreatment (550 W, 30 min) and air drying temperature (65, 70 and 75 °C) on the drying rate and bioactive compounds of chokeberry fruit. Accordingly, chokeberries were dried directly or after ultrasound pretreatment, and the retention rate of bioactive properties, i.e., total phenolic, flavonoid and monomeric anthocyanin contents along with antioxidant capacity values, were examined. The required time for drying as well as the activation energy values were significantly lower in ultrasound treated samples. Logarithmic and Midilli models exhibited the best fit for drying kinetics of samples. The pretreatment led to significantly lower moisture content and a_w values. Compared to fresh sample, the highest retention rate for some bioactive properties was found in ultrasound pretreated sample dried at 75 °C. The ultrasonication also reduced the electricity consumption (kWh) in all temperature levels of drying operations. As a conclusion, the ultrasound pretreatment prior to drying had dual role by facilitating drying kinetics and by providing higher bioactive contents.

Design and Fabrication of Solar Dryer System for Food Preservation of Vegetables or Fruit

Food preservation has been practised in many parts of the world for thousands of years, and it applies to a wide range of foods, including fruits, vegetables, cereals, and meat. Food preservation techniques are canning, freezing, pickling, curing (smoking or salting), and drying. Food spoilage caused by moisture is caused by the growth of mould, yeast, bacteria, and enzymes in the food. The drying process removes enough moisture from food to significantly reduce the humidity level’s likelihood of these adverse outcomes. The material's content measures how much moisture is present in that substance. The moisture content of fresh food can range from 20 to 90 percent depending on the type of food consumed. There will be no signs of moisture in food that has been thoroughly dried before being chopped. We used the experimental analysis in this study to create a mathematical model that could be used to determine which parameter was most important in the design of a solar dryer. In the future, the model is expected to be a helpful design tool for estimating the short- and long-term performance of a solar dryer under load and overload scenarios. The simulation of a solar dryer system has been performed under conditions such as the gap between the glass and the absorber plate, and the impact of hole size. The optimal hole size and spacing between the glass and the absorber plate are determined.

Ultrasound, infrared and its assisted technology, a promising tool in physical food processing: A review of recent developments

Traditional food processing techniques can no longer meet the ever increasing demand for high quality food across the globe due to its low process efficiency, high energy consumption and low product yield. This review article is focused on the mechanism and application of Infrared (IR) and ultrasound (US) technologies in physical processing of food. We herein present the individual use of IR and US (both mono-frequency and multi-frequency levels) as well as IR and US supported with other thermal and non-thermal technologies to improve their food processing performance. IR and US are recent thermal and non-thermal technologies which have now been successfully used in food industries to solve the demerits of conventional processing technologies. These environmentally-friendly technologies are characterized by low energy consumption, reduced processing time, high mass-transfer rates, better nutrient retention, better product quality, less mechanical damage and improved shelf life. This work could be, with no doubt, useful to the scientific world and food industries by providing insights on recent advances in the use of US and IR technology, which can be applied to improve food processing technologies for better quality and safer products.

Effect of foliar application of selenium on morphological and physiological indices of savory (Satureja hortensis) under cadmium stress

Cadmium is a heavy metal that pollutes the environment and affects plants physiologically and morphologically. Selenium is considered as a beneficial element, with effective roles in increasing plant tolerance to environmental stresses. A greenhouse factorial pot experiment was conducted to study the impact of selenium on traits of Savory plants under Cd stress. Experimental factors included soil contamination with cadmium (0, 75, 100, and 150 μM) and foliar spraying of selenium (0, 10, 20, and 40 μM of Sodium Selenate). Biomass, photosynthetic pigments including chlorophyll a, chlorophyll b, total chlorophyll, proline, total soluble solids, cell membrane leakage, relative water content of leaves antioxidant enzymes, and Cd and Zn concentration in shoot and root were recorded. Results revealed that Cd stress decreased vegetative growth criteria, photosynthetic pigments include chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid almost, 55%, 57%, 57%, and 68%, respectively, while poline, cell membrane leakage, peroxidase (POD), and catalase (CAT) antioxidant enzymes were increased with increasing Cd concentrations. Foliar spray of selenium reduced the toxic effects of Cd stress on savory plants via enhancing of proline content and stimulation of CAT and POD enzymes and limitation of cell membrane leakage. Also, selenium foliar spray improved chlorophyll content under Cd stress condition and decreased cadmium accumulation 29% in root, respectively. In general, these results suggest that foliar application of selenium could mitigate Cd toxicity and improve growth and antioxidant capacity of savory under different level of cadmium heavy metal stress.