Effect of Osmotic Dehydration Pretreatment on the Drying Characteristics and Quality Properties of Semi-Dried (Intermediate) Kumquat (Citrus japonica) Slices by Vacuum Dryer

Effect of sodium alginate edible coating on drying behavior and quality characteristics of ripe pineapple slices

The increasing global demand for tropical fresh cut products is driven by their convenience, quality, and health benefits, highlighting the need for effective preservation methods. Pineapple slices were treated with antioxidant solution, osmodehydrated (OD) and edible sodium alginate coating was applied in different methods to investigate the effect of edible coating on osmotic dehydration, convection drying phenomena, and quality parameters of dried pineapple slices. The findings showed that edible coatings influenced drying kinetics and physicochemical properties of pineapple slices. The optimal drying temperature was identified as 60 °C, while color degradation occurred at 65 °C. Pineapple slices treated with sodium alginate after OD required the highest activation energy (65.93 kJ/mol) for moisture diffusion. Coatings enhanced ash content and moisture retention while reducing shrinkage and improving the rehydration ratio, vitamin C, and total phenolic content (TPC). Sensory assessment indicated improvements in color, flavor, texture, and overall acceptability for all coated samples. Notably, samples coated with sodium alginate after OD exhibited the most favorable physicochemical properties at 60 °C and the highest overall acceptability up to the 15th day of post-processing storage. These results underscore the potential of edible coatings to enhance the preservation and quality of pineapple slices, suggesting scopes for future research in pre-treatment technologies for drying.

Transforming lemon Peel into a sustainable reservoir of bioactives: A green osmotic dehydration strategy

Osmotic dehydration (OD) is a sustainable alternative, offering reduced energy consumption compared to traditional drying approaches. This study investigates the role of OD in stabilizing bioactive compounds in lemon peel, fostering sustainable citrus by-product applications. Employing Response Surface Methodology (RSM) framework, pivotal variables-temperature (30-60 °C), exposure time (60-180 min), and sucrose concentration (50-70°Brix)-were optimized to enhance water loss (WL) and solid gain (SG) while safeguarding bioactive retention. The optimal conditions (58.92 °C, 70°Brix, 159 min) yielded a WL of 3.4 g/g, SG of 1.5 g/g, and high sensory acceptability. The OD treated lemon peel powder exhibited substantial retention of bioactive compounds, including ascorbic acid (4.1 mg/g) and total phenols (2.3 mg gallic acid/g), surpassing untreated controls. This enhanced bioactive profile underscores its potential as a sustainable and functional ingredient in nutraceutical applications.

Enhancing drying characteristics and quality of fruits and vegetables using biochemical drying improvers: A comprehensive review

Traditional drying is a highly energy-intensive process, accounting for approximately 15% of total manufacturing cost, it often resulting in reduced product quality due to low drying efficiency. Biological and chemical agents, referred to as biochemical drying improvers, are employed as pretreatments to enhance both drying characteristics and quality attributes of fruits and vegetables. This article provides a thorough examination of various biochemical drying improvers (including enzymes, microorganisms, edible film coatings, ethanol, organic acids, hyperosmotic solutions, ethyl oleate alkaline solutions, sulfites, cold plasma, carbon dioxide, ozone, inorganic alkaline agents, and inorganic salts) and their effects on improving the drying processes of fruits and vegetables. Additionally, it introduces physical drying improvers (including ultrasonic, pulsed electric field, vacuum, and others) to enhance the effects of biochemical drying improvers. Pretreatment with biochemical agents not only significantly enhances drying characteristics but also preserves or enhances the color, texture, and bioactive compound content of the dried products. Meanwhile, physical drying improvers reduce moisture diffusion resistance through physical modifications of the food materials, thus complementing biochemical drying improvers. This integrated approach mitigates the energy consumption and quality degradation typically associated with traditional drying methods. Overall, this review examines the role of biochemical agents in enhancing the drying characteristics and quality of fruits and vegetables, offering a comprehensive strategy for energy conservation and quality improvement.

The Effect of Osmotic Dehydration Conditions on the Potassium Content in Beetroot (Beta vulgaris L.)

Osmotic dehydration as a process of removing water from food by immersing the raw material in a hypertonic solution is used primarily to extend the shelf life of products and as a pretreatment before further processing steps, such as drying and freezing. However, due to the bi-directional mass transfer that occurs during osmotic dehydration, the process can also be used to shape sensory properties and enrich the plant matrix with nutrients. The purpose of this study was to evaluate the effect of osmotic dehydration on the absorption of potassium by beet pulp immersed in various hypertonic solutions (sucrose, inulin, erythritol, xylitol solutions) with the addition of three chemical forms of potassium (gluconate, citrate, chloride) using variable process conditions. The study proved that osmotic dehydration is an effective way to enrich food. The highest potassium content (5779.03 mg/100 g) was found in a sample osmotically dehydrated in a 50% erythritol solution with 5.0% potassium chloride addition with a process that lasted 180 min and took place at 30 °C. The results obtained indicate the high potential of osmotic dehydration in improving the health values of food products. In addition, the antioxidant activity and proximate composition of osmotically dehydrated samples were also characterized in this study.

Advancement and Innovations in Drying of Biopharmaceuticals, Nutraceuticals, and Functional Foods

Drying is a crucial unit operation within the functional foods and biopharmaceutical industries, acting as a fundamental preservation technique and a mechanism to maintain these products' bioactive components and nutritional values. The heat-sensitive bioactive components, which carry critical quality attributes, necessitate a meticulous selection of drying methods and conditions backed by robust research. In this review, we investigate challenges associated with drying these heat-sensitive materials and examine the impact of various drying methods. Our thorough research extensively covers ten notable drying methods: heat pump drying, freeze-drying, spray drying, vacuum drying, fluidized bed drying, superheated steam drying, infrared drying, microwave drying, osmotic drying, vacuum drying, and supercritical fluid drying. Each method is tailored to address the requirements of specific functional foods and biopharmaceuticals and provides a comprehensive account of each technique's inherent advantages and potential limitations. Further, the review ventures into the exploration of combined hybrid drying techniques and smart drying technologies with industry 4.0 tools such as automation, AI, machine learning, IoT, and cyber-physical systems. These innovative methods are designed to enhance product performance and elevate the quality of the final product in the drying of functional foods and biopharmaceuticals. Through a thorough survey of the drying landscape, this review illuminates the intricacies of these operations and underscores their pivotal role in functional foods and biopharmaceutical production.

Unveiling the Influence of Osmotic Pretreatment on Dried Fruit Characteristics: A Meta-Analysis Approach

Considering the diverse findings regarding the impact of osmotic pretreatment on the quality of dried products, it is important to determine whether osmotic pretreatment can either maintain or reduce the quality of fruit products. Thus, the present study aimed to scrutinize research regarding the influence of osmotic pretreatment on the qualities of dried fruits through meta-analysis. The Scopus database was used to search for relevant articles. Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses protocol, 26 studies that met the criteria for meta-analysis were identified. The presentation included statistics (mean, standard deviation, sample size) and moderator variables (fruit types, osmotic agents, solution concentrations, drying methods, and drying temperatures). After pooling data using a random effects model, the OpenMEE software was used to conduct meta-analysis. The results showed that osmo-dried fruits had significantly decreased total color difference, titratable acidity, total flavonoid content, and vitamins B1 and B3 (P<0.05) and significantly increased β-carotene and 2,2-diphenyl-1-picrylhydrazyl levels (P<0.05). Osmotic pretreatment did not affect total phenolic content and vitamin C. Subgroup analysis highlighted the influence of moderator variables on the quality of osmo-dried fruits, with each fruit responding differently to osmotic pretreatment. Moreover, using 10% sugar solution as an additive effectively enhanced the quality of dried fruits. In addition, osmotic dehydration can be combined with convective drying at a temperature of 60°C for optimal results in the drying process.

Convective drying of Gardenia erubescens fruits: Effect of pretreatment, slice thickness and drying air temperature on drying kinetics and product quality

Gardenia erubescens fruits are regarded as nutrient-dense, capable of promoting nutritional and metabolic human health. However, they are seasonal and highly perishable which limits their consumption and wider utilization. In this study, the effect of slice thickness (3 mm and 5 mm), pretreatments (steam blanching and dipping in ascorbic acid solution) and drying air temperature (40 °C, 50 °C, 60 °C and 70 °C) on drying kinetics, color, β-carotene and vitamin C content of Gardenia erubescens fruits were investigated. The results showed that the drying time increased as slice thickness increased, and decreased as drying air temperature increased but did not follow any trend for pretreatment. The Page model (R2 values of 0.9998-0.9999) exhibited the best fit to the drying kinetics data. The diffusivity values (5.31 × 10-11 to 4.14 × 10-10 m2s-1) increased as the slice thickness and drying air temperature increased but had no linear trends with pretreatment. The activation energy ranged from 14.35 to 44.78 kJmol-1, with the highest being recorded by 5 mm untreated samples and the lowest by the 3 mm blanched samples. The total color change (ΔE*) of the samples generally decreased as the drying air temperature increased but increased as the slice thickness increased. The ascorbic acid pretreated samples had the least color change, followed by the untreated samples while the blanched samples had the highest change. Overall, the 5 mm ascorbic acid pretreated samples dried at 70 °C had the least color change (13.33 ± 0.52). The blanching and dipping in ascorbic acid solution generally yielded lower β-carotene and vitamin C values as compared to the untreated samples. The 3 mm ascorbic acid pretreated samples dried at 50 °C recorded the lowest β-carotene (42.70 ± 3.21 μg/100 g) while the 5 mm ascorbic acid pretreated samples had the lowest vitamin C (37.50 ± 2.65 mg/100 g) at 70 °C. Pretreatments and drying air temperatures showed mixed effects on the drying characteristics, color, β-carotene and vitamin C contents of fruit slices. The findings, therefore, indicate that a compromise may have to be made on the aforementioned processing conditions in order to meet the desired attributes of one's interest.

Effect of dielectric barrier discharge (DBD) cold plasma-activated water pre-treatment on the drying properties, kinetic parameters, and physicochemical and functional properties of Centella asiatica leaves

Centella asiatica L. (CA) is a medicinal plant that gained significant commercial and research interest because of its bioactive compounds, which have functional properties such as antioxidant activity. However, it must be dried before use to improve its shelf life and prepare it for food and pharmaceutical applications. Therefore, in this investigation CA leaves were pre-treated with blanching and cold plasma activated water (CPAW), followed by recirculatory hot air and vacuum drying at 40, 50, and 60 °C. Vacuum-drying took 150-720 min, while hot-air drying took 60-180 min to dry. Page and Logarithmic models best fit for leaf drying kinetics, according to AIC, with R² between 0.966 and 0.999 and RMSE between 0.001 and 0.069. CPAW pre-treatment increased leaf quality more than blanching in vacuum drying. Drying leaves at 40 °C boosted antioxidants (4021.462 μg TE (g dw)^-1 and 3.356 mg GAEAC (g dw)^-1), TPC (35.049 mg GAE (g dw)^-1), and TFC (311.274 mg QE (g dw)^-1) and is recommended. Vacuum-drying with CPAW pre-treatment preserved leaf microstructure better than hot-air drying. This study illuminates CA leaf drying behaviour and allow mass production without damaging bioactive components. These results could be used as a roadmap for future technological advances that will make it possible to use the bioactive components of CA in food formulation.