Drying Technologies in Food Processing

Recently, consumers are paying more attention to healthy diets and often seek products with a high number of bioactive compounds, such as fruit and vegetables [1,2]. Due to the seasonality of raw materials, some fruits and vegetables are available on the market in a fresh state only for a short period during the year. Furthermore, after harvesting, there can be a surplus of raw materials. Drying is one of the most frequently used processing methods that enable surplus to be handled [3,4]. However, the drying process is used in different processes during food production and has an impact on the quality of the final product [3,5]. Different methods of drying and pretreatments are used to obtain high-quality products. Osmotic dehydration could be applied as a pretreatment before the drying process to partially remove water from the cellular tissue via the immersion of fruit and vegetables in hypertonic aqueous solutions, reducing drying time, as well as decreasing process costs and improving the taste of the final product [1,6,7]. However, osmotic dehydration might also be used to obtain minimally processed fruit and vegetable products [8]. To accelerate mass transfer during osmotic dehydration and drying, in recent years, new techniques, such as pulsed-vacuum, high and low pressure, power ultrasound, pulsed electric fields, etc., have been used [9–11]. In this Special Issue, “Drying Technologies in Food Processing”, a comprehensive overview of the application of emerging and unconventional technologies prior to and during osmotic dehydration is presented. These innovative approaches are employed to produce high-quality osmodehydrated and dried products. Additionally, this Special Issue offers valuable insights into the principles and fundamentals of nonthermal technologies and their applications in food processing. This will allow researchers and experts to gain valuable insights into the potential use of different technologies in food processing, enhancing the efficiency of osmotic dehydration and drying methods

Safety, quality, and processing of fruits and vegetables

Nowadays, one of the main objectives of the fruit and vegetable industry is to develop innovative novel products with high quality, safety, and optimal nutritional characteristics in order to respond with efficiency to the increasing consumer expectations. Various emerging, unconventional technologies (e.g., pulsed electric field, pulsed light, ultrasound, high pressure, and microwave drying) enable the processing of fruits and vegetables, increasing their stability while preserving their thermolabile nutrients, flavour, texture, and overall quality. Some of these technologies can also be used for waste and by-product valorisation. The application of fast noninvasive methods for process control is of great importance for the fruit and vegetable industry. The following Special Issue \u201cSafety, Quality, and Processing of Fruits and Vegetables\u201d consists of 11 papers, which provide a high-value contribution to the existing knowledge on safety aspects, quality evaluation, and emerging processing technologies for fruits and vegetables

Sustainable Approach for Development Dried Snack Based on Actinidia deliciosa Kiwifruit

Featured Application The drying process enables the obtainment of snacks that can be stored at room temperature. Freeze drying better preserves bioactive compounds compared to hot air drying; however, its high porosity requires a specific storage method-without access to the air. The freeze-dried samples were more appreciated by consumers than the air-dried ones, as well as those containing a small amount of additional sweetener. The valorization of waste products can help to improve the health and well-being of consumers through the development of new products enriched with valuable bioactive compounds. Thus, guaranteeing improved environmental sustainability as well as attractive food products. The aim of this study was to evaluate the method of producing shelf-stable snacks based on kiwifruit with the objective of obtaining an appealing snack with good taste, color, and nutritional value. Less valuable kiwifruits for size and shape were utilized in order to reduce kiwifruit production waste. To obtain the snacks, two drying methods were used: freeze-drying and hot air drying. Physical and chemical analyses were conducted. Furthermore, a sensory evaluation was undertaken. The results showed that both hot-air and freeze-drying methods are suitable for obtaining a good quality snack, which was attractive to consumers. However, the freeze-dried snack was better assessed than hot-air dried. Moreover, consumers preferred snacks with additional sucrose or trehalose to those without it. It was observed that products produced using the freeze-drying process had lower water content, and lower water activity, were brighter, had a more saturated color, and had similar or higher antioxidant activity, especially for samples made from kiwi, fennel, and spinach. The drying process allows for obtaining a snack that can be stored at room temperature. Freeze drying better preserved bioactive compounds compared to air drying. The freeze-dried samples were more appreciated by consumers than the air-dried and those containing sweetener

Effects of pulsed electric field-assisted osmotic dehydration and edible coating on the recovery of anthocyanins from in vitro digested berries

Berry fruits, such as strawberries and blueberries, are rich sources of anthocyanins. Several studies have been made on the impact of non-thermal treatments on safety, shelf-life and nutritional characteristics of such products, but the effects of these processes on anthocyanin stability during digestion in the gastrointestinal tract are still not completely clear. The aim of this study was to assess the recovery of anthocyanins after simulated gastrointestinal digestion of (1) strawberry samples, pre-treated with pulsed electric field (PEF) at 100 or 200 V\ub7cm 121, prior to osmotic dehydration (OD), and (2) blueberry samples coated with chitosan and procyanidin. After digestion, a significantly higher content of cyanidin-3-O-glucoside and malvidin-3-O-glucoside was quantified by LC-MS/MS in processed strawberry and blueberry samples, compared with the controls. The highest recovery of cyanidin-3-O-glucoside was detected in digested strawberry samples osmotically dehydrated with trehalose. The recovery of malvidin-3-O-glucoside was highest in digested blueberries coated with chitosan and stored for 14 days, compared with untreated samples or samples coated with chitosan and procyanidin. Our study shows the potential of mild PEF treatments combined with OD, or the use of edible coating, to obtain shelf-stable products without substantially affecting the composition or the stability of anthocyanins during digestion in the upper gastrointestinal tract

Effect of the Pulsed Electric Field Treatment on Physical, Chemical and Structural Changes of Vacuum Impregnated Apple Tissue in Aloe Vera Juices

Vacuum impregnation (VI) stands as a diffusion-driven food processing method that has found recent application within the food industry, particularly for the cold formulation of fortified food products. Pulsed electric field (PEF) treatment can affect the food structure, influencing therefore the mass transfer phenomena during the further processing. Thus, the study aimed at investigating the effect of PEF treatment on selected physicochemical properties of vacuum-impregnated apples. Apple slices were vacuum impregnated with aloe vera juice solution with or PEF treatment at different intensities (125, 212.5 or 300 V/cm). The PEF was applied as a pretreatment—applied before the VI process as well as posttreatment—applied after the VI process. The VI process with aloe vera juice resulted in a sample weight increase of over 24% as well as structural changes, partial cell viability loss and color alteration. In addition, the decrease of bioactive compounds was observed, while antioxidant activity remained at a similar level as in raw material. PEF treatment adversely affected vacuum impregnation efficiency, causing microstructural changes and cell viability loss. Additionally, chemical composition modifications were evident through thermogravimetric analysis (TGA) and Fourier Infrared Spectroscopy (FTIR) analyses. Tissue hardness decreased significantly due to structural damage and caused high leakage from plant tissue, which resulted in hindering saturation with aloe vera juice during the VI process. Additionally, reduced bioactive substance content after PEF treatment was observed and the VI process did not restore apple samples of the bioactive compounds from aloe vera juice

The Effect of Marinating on Fatty Acid Composition of Sous-Vide Semimembranosus Muscle from Holstein-Friesian Bulls

The aim of the study was to evaluate the effect of two commercial oil marinades on marinated bovine semimembranosus muscles’ (n = 12) fatty acid composition. Fatty acids were determined in unmarinated raw and sous-vide beef and marinated muscles with two different marinades. The application of marinating changed the fatty acid composition in sous-vide beef. The sum of saturated fatty acids (SFA) and n-6/n-3 ratio decreased. However, the sum of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA), including n-6 and n-3, increased in marinated sous-vide beef, while a proportion of conjugated linoleic acid (CLA) and arachidonic acid (AA) de-creased. The concentration (mg/100 g) of the sum of SFA and CLA in sous-vide beef was unaffected by marinating; however, the treatment significantly increased the sum of MUFA, PUFA, n-6 fatty and n-3 fatty acid concentrations. Using marinades containing canola oil and spices prior to the sous-vide treatment of beef was effective in improving its fatty acid composition

Influence of pulsed electric field and ohmic heating pretreatments on enzyme and antioxidant activity of fruit and vegetable juices

The objective of this work was to optimize pulsed electric field (PEF) or ohmic heating (OH) application for carrot and apple mashes treatment at different preheating temperatures (40, 60 or 80 \ub0C). The effect of tissue disintegration on the properties of recovered juices was quantified, taking into account the colour change, the antioxidant activity and the enzyme activity of peroxidase (POD) in both carrot and apple juice and polyphenol oxidase (PPO) in apple juice. Lower \u394E and an increase of the antioxidant activity were obtained for juice samples treated with temperature at 80 \ub0C with or without PEF and OH pretreatment compared with those of untreated samples. The inactivation by 90% for POD and PPO was achieved when a temperature of 80 \ub0C was applied for both carrot and apple mash. A better retention of plant secondary metabolites from carrot and apple mashes could be achieved by additional PEF or OH application. Obtained results are the basis for the development of targeted processing concepts considering the release, inactivation and retention of ingredients

Kiwifruit waste valorisation through innovative snack development

Currently, in the case of kiwifruits, those fruit with a weight lower than 65 g are considered waste. The production of dried snacks with high nutritional functionality could be a valid alternative to use the kiwifruit waste, with positive economic impact on the entire production chain. Therefore, the aim of this work was to evaluate the effect of pulsed electric field – PEF (200 V cm-1) and/or osmotic dehydration – OD (trehalose at 40%) pre-drying treatments on drying kinetics at 50, 60, and 70°C, and on colour and nutritional properties (vitamin C and antioxidant compounds) of ‘Jintao’ (yellow-fleshed) kiwifruit snacks. At every temperature, the PEF treated snacks showed the highest drying rate. Moreover, PEF treatment appeared to be a valid innovative alternative for the production of fruit snacks with high nutritional quality. A better retention of vitamin C and antioxidant compounds was obtained in dried yellow kiwifruit subjected to PEF treatment

The impact of pulsed electric field on the extraction of bioactive compounds from beetroot

Beetroot is a root vegetable rich in different bioactive components, such as vitamins, minerals, phenolics, carotenoids, nitrate, ascorbic acids, and betalains, that can have a positive effect on human health. The aim of this work was to study the influence of the pulsed electric field (PEF) at different electric field strengths (4.38 and 6.25 kV/cm), pulse number 10\u201330, and energy input 0\u201312.5 kJ/kg as a pretreatment method on the extraction of betalains from beetroot. The obtained results showed that the application of PEF pre-treatment significantly (p < 0.05) influenced the efficiency of extraction of bioactive compounds from beetroot. The highest increase in the content of betalain compounds in the red beet\u2019s extract (betanin by 329%, vulgaxanthin by 244%, compared to the control sample), was noted for 20 pulses of electric field at 4.38 kV/cm of strength. Treatment of the plant material with a PEF also resulted in an increase in the electrical conductivity compared to the non-treated sample due to the increase in cell membrane permeability, which was associated with leakage of substances able to conduct electricity, including mineral salts, into the intercellular space

Air-drying temperature changes the content of the phenolic acids and flavonols in white mulberry (Morus alba l.) leaves

The white mulberry leaves are typically available on the market in dried or encapsulated form. It was assumed in the study that appropriate drying of leaves of the white mulberry is significant for obtaining intermediate products with high content of compounds having anti-oxidative activity. The purpose of the study was to determine the influence of the temperature of mulberry leaves air drying on the content of phenolic acids and flavonols. It has been determined that the content of these compounds in the leaves depended on the drying temperature. Drying at 60 \ub0C favored release of phenolic acids and flavonols from complexes and/or formation of new compounds. Their total content was 22% higher than in leaves dried at 30 \ub0C. Drying at 90 \ub0C reduced the phenolic acid and flavonol content by 24%. The most favorable drying temperature was 60 \ub0C