Effects of osmotic dehydration (with and without sonication) and pectin-based coating pretreatments on functional properties and color of hot-air dried apricot cubes

Evaluation of Organic Acids and Ultrasound as Pretreatment in Convective Drying Kinetics and Quality Parameters of Pumpkin

There is a growing interest in the food industry in new drying technologies that reduce the time required for dehydration, combined with low energy consumption, low environmental impact, and maintenance of the overall quality of the product. This work investigated convective drying of pumpkin with and without ultrasound-organic (citric or acetic) acid pretreatment for different durations (10, 20, and 30 min). Drying was carried out at 60 °C, and the Wang and Singh model had the best fit for the experimental data. Samples pretreated for 30 min had the shortest drying times. Water diffusivities ranged from 6.68 × 10-8 m2/s to 7.31 × 10-8 m2/s, with the pretreated samples presenting the highest values. The dried pumpkin water activity values were below 0.60. Regarding color parameters, there was a slight increase in luminosity, a slight reduction in a*, and a significant increase in b*. Drying resulted in the loss of ascorbic acid and phenolic compounds, but the samples pretreated with citric acid showed better retention. There was also a reduction in the total carotenoid content, but samples pretreated with acetic acid for 10 and 20 min showed the best retention.

Effect of ultrasound combined with chemical pretreatment as an innovative non-thermal technology on the drying process, quality properties and texture of cherry subjected to radio frequency vacuum drying

To obtain high-quality cherry products, ultrasound (US) combined with five chemical pretreatment techniques were used on cherry prior to radio frequency vacuum drying (RFV), including carboxymethyl cellulose coating (CMC), cellulase (CE), ethanol (EA), isomaltooligosaccharide (IMO), and potassium carbonate + ethyl oleate (PC + AEEO). The effect of different pretreatments (US-CMC, US-CE, US-EA, US-IMO, US-(PC + AEEO)) on the drying characteristics, quality properties, texture, and sensory evaluation of cherries was evaluated. Results showed that the dehydration time and energy consumption were decreased by 4.17 - 20.83 % and 3.22 - 19.34 %, respectively, and the contents of individual sugars, soluble solid, total phenolics (TPC), natural active substances, total flavonoids (TFC), and antioxidant properties (DPPH, ABTS and FRAP) were significantly increased after US combined with five chemical treatments (P < 0.05). Moreover, the pretreatment played important role in improving texture properties and surface color retention in the dried cherries. According to the sensory evaluation analysis, the dehydrated cherries pretreated with US-CMC exhibited the highest overall acceptance, texture, crispness, color, and sweet taste showed lower off-odor, bitter taste and sour taste compared to control and other pretreatments. The findings indicate that US-CMC pretreatment is a promising technique for increasing physicochemical qualities and dehydration rate of samples, which provides a novel strategy to processing of dried cherry.

Effect of various different pretreatment methods on infrared combined hot air impingement drying behavior and physicochemical properties of strawberry slices

In current work, the effect of freezing (F), ultrasound (U), and freeze- ultrasound (FU) pretreatment on infrared combined with hot air impingement drying kinetics, cell ultrastructure, enzyme activity, and physicochemical properties of strawberry slices were explored. Results showed that FU pretreatment enhanced cell membrane permeability via forming micropores, altered water status by transforming bound water into free water and thus promoted moisture diffusivity and decreased drying time by 50% compared to the control group. FU pretreatment also extensively decreased pectin methylesterase enzyme activity and maintained quality. The contents of total phenols, anthocyanins, vitamin C, antioxidant activity, and a* value of dried strawberries pretreated by FU were extensively increased compared to the control group. U and FU pretreatments were beneficial for retaining aromatic components and organic sulfides according to e-nose analyses. The findings indicate that FU is a promising pretreatment technique as it enhances drying process and quality of strawberry slices.

Gamma irradiation and ozone application as preservation methods for longer-term storage of bee pollen

Bee pollen is a healthy product with a good nutritional profile and therapeutic properties. Its high moisture content, however, promotes the growth of bacteria, molds, and yeast during storage commonly result in product degradation. Therefore, the aim of this study is to assess the effectiveness of gamma irradiation (GI) and ozone (OZ) as bee pollen preservation methods for longer storage time, as well as whether they are influenced by pollen species. To do that, GI at a dosage of 2.5, 5.0, and 7.5 kGy was applied at a rate of 0.68 kGy/h and OZ application at a concentration of 0.01, 0.02, and 0.03 g/m3 was applied for one time for 6 h, to Egyptian clover and maize bee pollen, then stored at ambient temperature for 6 months. We then determined the total phenolic content (TPC) and antioxidant activity of treated and non-treated pollen samples at 0, 3, and 6 months of storage. Total bacteria, mold, and yeast count were also evaluated at 0, 2, 4, and 6 months. Statistical analyses revealed that, TPC, antioxidant, and microbial load of both clover and maize pollen samples were significantly (p < 0.05) affected by both treatment and storage time and their interaction. Both methods were extremely effective at preserving the antioxidant properties of pollen samples after 6 months of storage at room temperature. Furthermore, the highest concentrations of both GI and OZ applications completely protected pollen samples from mold and yeast while decreasing bacterial contamination. GI at the highest dose (7.5 KGy) was found to be more effective than other GI doses and OZ application in preserving biologically active compounds and lowering the microbial count of pollen samples for 6 months. As a result, we advise beekeepers to use GI at this dose for longer-term storage.

Effective drying processes for Taikor (Garcinia pedunculata Roxb.) fruit by ultrasound-assisted osmotic pretreatment: Analysis of quality and kinetic models

The present study aimed to analyze and establish an effective combination of ultrasound and immersion pretreatment processes for drying Taikor (Garcinia pendunculata Roxb.) fruits. Taikorslices were first immersed in 10 % sucrose, fructose, and glucose solution. Then, the immersed slices were treated in an ultrasonic bath at 30 °C for 10, 20, and 30 min. Drying operations were carried out at 50, 60, and 70 °C, with a fixed relative humidity of 30 %. The Page, Newton, Henderson and Pabis, and Weibull distribution models were fitted to the obtained drying data to determine the best kinetic model that effectively describes the drying properties ofTaikor. After drying operations, changes in quality parameters, e.g., β-carotene, vitamin C, B vitamins, color, antioxidant activities, and microbial loads, were measured to obtain the best drying temperature and the most effective pretreatment combination with minimum loss of nutrients of the sample. Among different kinetic models, both Page and Weibull distribution models showed the best R2 values of 0.9867 and 0.9366, respectively. The chemical properties were preserved to the greatest extent possible by drying at 50 °C with glucose pretreatment. The color parameters were better preserved by fructose pretreatment. Sonication time also had profound effect on the quality parameters of dried Taikor slices. However, higher temperature drying required a shorter time for drying and exhibited better performance in microbial load reduction. This study's findings will help to establish an effective drying condition forGarcinia pedunculatafruits.

Recent progress and treatment strategy of pectin polysaccharide based tissue engineering scaffolds in cancer therapy, wound healing and cartilage regeneration

Natural polymers and its mixtures in the form of films, sponges and hydrogels are playing a major role in tissue engineering and regenerative medicine. Hydrogels have been extensively investigated as standalone materials for drug delivery purposes as they enable effective encapsulation and sustained release of drugs. Biopolymers are widely utilised in the fabrication of hydrogels due to their safety, biocompatibility, low toxicity, and regulated breakdown by human enzymes. Among all the biopolymers, polysaccharide-based polymer is well suited to overcome the limitations of traditional wound dressing materials. Pectin is a polysaccharide which can be extracted from different plant sources and is used in various pharmaceutical and biomedical applications including cartilage regeneration. Pectin itself cannot be employed as scaffolds for tissue engineering since it decomposes quickly. This article discusses recent research and developments on pectin polysaccharide, including its types, origins, applications, and potential demands for use in AI-mediated scaffolds. It also covers the materials-design process, strategy for implementation to material selection and fabrication methods for evaluation. Finally, we discuss unmet requirements and current obstacles in the development of optimal materials for wound healing and bone-tissue regeneration, as well as emerging strategies in the field.

Dehydration-rehydration vegetables: Evaluation and future challenges

In this review, the rehydration kinetics model, the quality factors affecting of vegetables during rehydration process, the future challenges and development direction of rehydration process were comprehensively analyzed. Based on the fitting equation for the change in moisture content during rehydration, a suitable rehydration model can be selected to describe the rehydration process of vegetables. Optimal pre-treatment, drying and rehydration methods were selected by considering quality, energy consumption and environmental aspects, and new technologies were developed to improve the quality characteristics of rehydrated vegetables. It is necessary to classify vegetables according to their shape and type to establish the criteria of rehydration processing through mathematical modeling. Industrial production from pre-treatment to product packaging will be precisely adjusted through process parameters. Furthermore, improvements the quality of rehydrated vegetables can be considered in terms of the structural and compositional aspects of the cell wall and cell membrane.

Effects of gum-based coatings combined with ultrasonic pretreatment before drying on quality of sour cherries

Application of pretreatment methods such as ultrasound and edible coatings is used to reduce processing time and/or preserve food product quality in drying technology. The aim of this research was to measure the impacts of gum-based coatings (guar, sodium alginate, and basil seed gums) in combination with sonication before drying on total phenolic content (TPC), antioxidant capacity (AC), effective water diffusivity (Deff), total color difference (ΔE), surface shrinkage (SS), and rehydration ratio (RR) of sour cherries. Ultrasonic pretreatment (40 kHz, 150 W, at 25 °C, for 12 min) increased the TPC, AC, Deff, and RR, and decreased the drying time, ΔE, and SS values of sour cherries. Edible coating increased the TPC, AC, drying time, and RR, and decreased the Deff, ΔE, and SS values of sonicated sour cherries. The TPC for untreated, uncoated-sonicated, guar gum-coated, sodium alginate-coated, and basil seed gum-coated sour cherries were 2965.9, 3398.1, 3480.8, 3511.0, and 3898.3 Âµg gallic acid equivalent/g dry, respectively. The highest value of AC (71.2±3.7 %) was observed on coated sour cherries by basil seed gum. The experimental data for drying curves were fitted to several widely used models, and the Midilli model using the experimental constants that best represent the drying rate of sour cherries. The edible coatings significantly reduced the color changes and shrinkage of dried sour cherries, with the lowest ΔE and SS values in the basil seed gum-coated samples (p < 0.05).

Investigating the Role Played by Osmotic Pressure Difference in Osmotic Dehydration: Interactions between Apple Slices and Binary and Multi-Component Osmotic Systems

This study was performed to investigate a strategy to interpret the osmotic dehydration (OD) process through a focused exploration of osmotic pressure dynamics. The investigation first delved into the relationship between dehydration rate and the osmotic pressure difference between food and an osmotic solution. Apple slices was used as a model food material, and the OD process was conducted via sucrose, glucose, and maltose. The positive correlation between the osmotic pressure difference between food and osmotic solution and the dehydration rate suggested that this pressure difference served as the primary driving force for mass transfer within the OD process; for example, in 60% wt sucrose solution, the osmotic pressure of the solution decreased from 15.60 MPa to 12.98 MPa in the first 30 min, while the osmotic pressure of fresh apple slices increased from 1.49 MPa to 4.05 MPa; and this correlation between dehydration rate and osmotic pressure difference in product tissue and osmotic solution followed a linear relationship. Then, the study went further to investigate augmenting osmotic pressure of osmotic solution (sucrose and fructose) by adding auxiliary solutes (sodium chloride and calcium lactate). The results showcased that augmenting osmotic pressure within a sugar-based solution could be realized through the introduction of additive solutes, and what is more important is that this augmentation displayed a synergistic effect, which was more pronounced in solutions of lower sugar concentration. For example, the osmotic pressure of 45%wt fructose solution was 8.88 MPa, which could be increased to 10.05 MPa by adding 0.075% wt NaCl, while adding 0.075% wt NaCl to 59.14% wt fructose solution could increase osmotic pressure from 20.57 MPa to 21.22 MPa. In essence, this study proposed a strategic approach to studying the OD process by spotlighting osmotic pressure as a pivotal factor.

Advances in formulation, functionality, and application of edible coatings on fresh produce and fresh-cut products: A review

With the increasing population of the world food demand is also increasing but unfortunately, many countries in the world are lacking suitable and economical postharvest preservation techniques to minimize increasing postharvest losses. To ensure food security advanced production technologies, distribution systems and minimum losses should be ensured to give accessibility of food to all population groups. Innovative preservation techniques should be adopted by the agriculture sector to meet intercontinental distribution and demand for fresh produce. The application of the edible coating is a novel technique in postharvest preservation due to its simple application, ecofriendly nature, and effectiveness. Edible coatings can also improve the quality and safety aspects of fresh produce and thus extends shelf life. This review aimed to update information about recent advances in edible coating formulation and application mainly on fresh-cut /minimally processed fruits and vegetables. This information will be helpful for processors to select the best coating material and its effective concentration for different fresh and minimal processed vegetables.

Effect of amla and ginger powders on quality criteria of African catfish (Clarias gariepinus) fingers

Catfish (Clarias gariepinus) meat isn't preferred by consumers in compared to other fish species meat, thus to enhance the use of catfish meat, ready to eat catfish fingers were prepared with some plants additives (amla and ginger powder). The mean objective of this study was to assess the impact of amla and ginger powder on catfish finger qualities in terms of physical, chemical, microbiological, and sensorial parameters under stored at a low temperature (5 ± 1 °C). The obtained results were compared with those of a control sample (basic formula) and a sample containing the synthetic antioxidant. During the storage period, the levels of pH, thiobarbituric acid, total volatile basic nitrogen, trimethylamine, total bacteria count, psychrophilic bacteria, molds and yeasts counts increased dramatically, although the values remained within acceptable ranges. The findings also revealed, that amla and ginger powder considerably (p < 0.05) reduced the changes in quality parameters, as well as there was a considerable increase in the quality parameter in all treated samples than in the control. Finally, amla and ginger powder can be a substitute for synthetic antioxidants and antimicrobials. These findings suggest that the powder of amla and ginger are suitable for use as a natural antioxidants and antimicrobials to extend the shelf-life of animal products.

Stability of Fructooligosaccharides in Convectively Dried Fruits After Initial Osmoconcentration

The aim of this study was to determine the effect of temperature and time of convective drying on the content of fructooligosaccharides (FOS) in apples, plums and strawberries to which FOS had been introduced by osmoconcentration. The share of oligosaccharides in total sugars was analyzed. In apple tissue, fructooligosaccharides were stable in the temperature range 40–80 °C during drying for up to 8 h. Convective drying of osmotically dehydrated strawberries caused FOS losses; the FOS retention after 8 h at 80 °C was 40%. In the case of plums, 40% retention was recorded after just two hours at 80 °C. Therefore, in the case of some fruits, obtaining a satisfactory level of fructooligosaccharides in the dried material with the assumed level of dry substance requires the determination of appropriate process parameters.

Current Advancements in Pectin: Extraction, Properties and Multifunctional Applications

Pectin is a heterogeneous hydrocolloid present in the primary cell wall and middle lamella in all dicotyledonous plants, more commonly in the outer fruit coat or peel as compared to the inner matrix. Presently, citrus fruits and apple fruits are the main sources for commercial extraction of pectin, but ongoing research on pectin extraction from alternate fruit sources and fruit wastes from processing industries will be of great help in waste product reduction and enhancing the production of pectin. Pectin shows multifunctional applications including in the food industry, the health and pharmaceutical sector, and in packaging regimes. Pectin is commonly utilized in the food industry as an additive in foods such as jams, jellies, low calorie foods, stabilizing acidified milk products, thickener and emulsifier. Pectin is widely used in the pharmaceutical industry for the preparation of medicines that reduce blood cholesterol level and cure gastrointestinal disorders, as well as in cancer treatment. Pectin also finds use in numerous other industries, such as in the preparation of edible films and coatings, paper substitutes and foams. Due to these varied uses of pectin in different applications, there is a great necessity to explore other non-conventional sources or modify existing sources to obtain pectin with desired quality attributes to some extent by rational modifications of pectin with chemical and enzymatic treatments.

Impact of Gum Arabic Coating Pretreatment on Quality Attributes of Oven-Dried Red Raspberry (Rubus idaeus L.) Fruit

The present study evaluated the effect of gum arabic (GA) edible coating pretreatment on the quality of dried red raspberries. Red raspberries were independently pretreated with varied concentrations of GA (3, 5, and 10% (w/v) by dipping for 2 min before oven-drying at 60 °C until the moisture content was below 8% (18–24 h). Raspberries dipped in distilled water were used as the control samples. Quality attributes including colour, moisture content, water activity (aw), hardness, hygroscopicity, rehydration capacity, total soluble solids (TSS), titratable acidity (TA), pH, anthocyanin composition, ascorbic acid (AA) content, total phenolic content (TPC), antioxidant activity, peroxidase (POD), and polyphenol oxidase (PPO) enzyme activity were investigated. GA pretreatment of the raspberries improved the aw (lower), hardness (lower), TSS, TSS/TA ratio, BrimA, AA content, and TPC, whilst it significantly (p < 0.05) reduced the colour properties (redness, chroma, hue angle, and total colour differences) and the total anthocyanin content when compared with the control samples. The DPPH radical scavenging activity, POD, and PPO enzymes residual activities were not significantly (p > 0.05) affected by GA pretreatment. Five different types of anthocyanins, including cyanidin dihexoside, cyanidin 3-O-galactoside, cyanidin 3-O-glucosyl-rutinoside, and cyanidin 3-O-rutinoside were identified and quantified with cyanidin dihexoside being the primary anthocyanin, varying from 951.18–1053.70 µg/g DM. GA pretreatment of raspberries between 3 and 5% could result in improved physicochemical, antioxidant properties and minimum loss of anthocyanins.

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

The effect of osmotic dehydration (OD) pretreatments at different temperatures and immersion times on drying characteristics, total phenolic content (TPC), total antioxidant activity (TAA) (DPPH and CUPRAC methods), and color of kumquat slices dried under vacuum conditions (70 °C-100 mbar) was investigated. The OD pretreatment was performed in a sucrose solution (45 °Bx) at the temperatures of 40 and 50 °C and immersed at times of 30, 60, and 90 min. OD before vacuum drying decreased the total required drying time by up to 70 min compared to the control non-pretreated samples. Page, Modified Page, Henderson Pabis, and Two Terms Exponential models were found to satisfactorily describe the drying behavior of thin layer dried kumquat slices. The minimum and maximum values of effective moisture diffusivity (Deff) for semi-dried kumquat slices were 5.04 × 10⁻⁸ to 7.19 × 10⁻⁸, respectively. OD treatments induced a decline in TPC (5.30–33.92%) and TAA (23.63–59.34% and 4.17–31.67% for DPPH and CUPRAC assays, respectively) of kumquat slices. It was observed that OD pre-treatment can decrease the gross drying time, and make the color and sensorial attributes of dried kumquats better.

Osmo-air drying of banana slices: multivariate analysis, process optimization and product quality characterization

In the present work, osmotic dehydration (OD) was applied as a pretreatment to hot air drying of banana slices and the effect of OD parameters on mass transfer characteristics, color profile was analysed. Principal component analysis (PCA) of OD process revealed that solid gain, weight reduction, water loss and total soluble solids were positively correlated with each other but were found to be negatively correlated with moisture content (MC) of sample. Response surface methodology was used for optimizing the OD of banana slices and and the optimum conditions were 61.26°Brix sucrose concentration at 50 °C for 6 h, resulting in moisture reduction from 75 to 49.78%. PCA-biplot of osmo-air drying (OAD) process showed the association among response parameters, which further revealed a positive correlation of MC with bioactive components. Additionally, OAD samples were also studied for microstructure and Fourier Transform Infra-red analysis. Addition of calcium lactate to sucrose solution resulted in preserving the firmness and bioactive components during osmosis, in addition to fortifying the sample with calcium. The present study provides new possibilities for food industries in preserving the ripe banana and developing calcium fortified functional food products.

Post-industrial context of cassava bagasse and trend of studies towards a sustainable industry: A scoping review - Part I

Background: The cassava starch industry is recognized as a source of negative externalities caused by the agroindustrial waste 'cassava bagasse'. Even though options for bioconversion of cassava bagasse have been introduced, it is also true that hundreds of tons of this waste are produced annually with the consequent negative environmental impact. This agroindustrial context highlights the need for further research in technological proposals aimed at lowering the water contained in cassava bagasse. Methods: We report a scoping review of studies from 2010-2021 that mention the uses of cassava bagasse, as well as the technological options that have become effective for drying fruits and vegetables. The method used for selecting articles was based on the Preferred Reporting Items for Systematic Review and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) method. Articles selected were taken from the databases of ScienceDirect, Google Scholar, Scopus and Springer. Results : This review highlights fruit and vegetable osmotic dehydration and drying studies assisted by the combination of emerging technologies of osmotic pressure, ultrasound, and electrical pulses. Studies that take advantage of cassava bagasse have focused on biotechnological products, animal and human food industry, and development of biofilms and biomaterials. Conclusions: In this review, we found 60 studies out of 124 that show the advantages of the residual components of cassava bagasse for the development of new products. These studies do not mention any potential use of bagasse fiber for post-industrial purposes, leaving this end products' final use/disposal unaddressed. A viable solution is osmotic dehydration and drying assisted with electrical pulse and ultrasound that have been shown to improve the drying efficiency of fruits, vegetables and tubers. This greatly improves the drying efficiency of agro-industrial residues such as husks and bagasse, which in turn, directly impacts its post-industrial use.

The Influence of Polyols on the Process Kinetics and Bioactive Substance Content in Osmotic Dehydrated Organic Strawberries

In recent years, an increasing interest in reducing sugar consumption has been observed and many studies are conducted on the use of polyols in the osmotic dehydration process to obtain candied or dried fruits. The studies in the literature have focused on the kinetics of the process as well as the basic physical properties. In the scientific literature, there is a lack of investigation of the influence of such polyol solutions such as sorbitol and mannitol used as osmotic substances during the osmotic dehydration process on the contents of bioactive components, including natural colourants. Thus, the aim of the study was to evaluate the impact of polyols (mannitol and sorbitol) in different concentrations on the process kinetics and on chosen physical (colour and structural changes) as well as chemical (sugars and polyol content, total anthocyanin content, total polyphenol content, vitamin C, antioxidant activity) properties of osmotic-dehydrated organic strawberries. Generally, the results showed that the best solution for osmotic dehydration is 30% or 40% sorbitol solutions, while mannitol solution is not recommended due to difficulties with preparing a high-concentration solution and its crystallization in the tissue. In the case of sorbitol, the changes of bioactive compounds, as well as colour change, were similar to the sucrose solution. However, the profile of the sugar changed significantly, in which sucrose, glucose, and fructose were reduced in organic strawberries and were partially replaced by polyols.

Effects of carboxymethyl cellulose/pectin coating combined with ultrasound pretreatment before drying on quality of turmeric (Curcuma longa L.)

Turmeric is an herb with multiple bioactive substances and health benefits. Drying is one of the most important steps of its processing and sales. In order to obtain high-quality turmeric products, we used five different pretreatment methods to treat turmeric prior to pulse-spouted microwave vacuum drying (PSMVD), including carboxymethyl cellulose coating (CMC), pectin coating (P), ultrasound (US) and their combination (CMCUS or PUS). The effect of different pretreatments on the drying kinetics, quality attributes and microstructure of turmeric were evaluated. Results showed that the US pretreatment had the shortest drying time (60 min), while coating treatment did not significantly affect drying rate. Dried turmeric with coating pretreatment had lower rehydration ratio and water adsorption capacity compared with individual ultrasound treatment. Carboxymethyl cellulose coating protected bioactive substances better than pectin coating. Moreover, CMCUS pretreatment showed significantly lower total color change, higher curcumin content, total phenols and flavonoid content as well as antioxidant capacity in all dried samples. Microstructure observation showed that the polysaccharide coating covering the surface of turmeric might reduce the degradation of bioactive compounds. Therefore, the CMCUS pretreatment before PSMVD of turmeric was recommended due to the efficiency and quality protections.

Chitosan nanoparticles encapsulating lemongrass (Cymbopogon commutatus) essential oil: Physicochemical, structural, antimicrobial and in-vitro release properties

This study was aimed to encapsulate lemongrass (Cymbopogon commutatus) essential oil (LGEO) into chitosan nanoparticles (CSNPs) and to investigate their physicochemical, morphological, structural, thermal, antimicrobial and in-vitro release properties. CSNPs exhibited spherical morphology with an average hydrodynamic size of 175-235 nm. Increasing EO loading increased the average size of CSNPs from 174 to 293 nm (at CS:EO ratio from 1:0 to 1:1.25). SEM and AFM confirmed the results obtained by hydrodynamic size indicating that EO loading led to formation of large aggregated NPs. The successful physical entrapment of EO within NPs was shown by fourier-transform infrared spectroscopy. X-ray diffractogram of loaded-CSNPs compared to non-loaded CSNPs exhibited a broad high intensity peak at 2θ = 19-25° implying the entrapment of LGEO within CSNPs. Thermogravimetric analysis (TGA) showed that encapsulated EO was decomposed at a temperature of 252 °C compared to a degradation temperature of 126 °C for pure LGEO, indicating a two-fold enhancement in thermal stability of encapsulated CSNPs. Differential scanning calorimetry also proved the physical entrapment of EO into polymeric matrix of chitosan. In-vitro release study showed a time- and pH-dependent release of EO into release media demonstrating a three-stage release behavior with a rapid initial release of EO, followed by a steady state migration of EO from its surrounding envelope at the later stages. Antimicrobial assay showed strong antimicrobial properties of free form of LGEO against the bacteria (both gram positive and gram negative) and fungi species tested. Moreover, loaded-CSNPs exhibited stronger antibacterial and anti-fungal activities than non-loaded CSNPs.

Effect of Alternative Preservation Steps and Storage on Vitamin C Stability in Fruit and Vegetable Products: Critical Review and Kinetic Modelling Approaches

Vitamin C, a water-soluble compound, is a natural antioxidant in many plant-based products, possessing important nutritional benefits for human health. During fruit and vegetable processing, this bioactive compound is prone to various modes of degradation, with temperature and oxygen being recognised as the main factors responsible for this nutritional loss. Consequently, Vitamin C is frequently used as an index of the overall quality deterioration of such products during processing and post-processing storage and handling. Traditional preservation methods, such as thermal processing, drying and freezing, are often linked to a substantial Vitamin C loss. As an alternative, novel techniques or a combination of various preservation steps ("hurdles") have been extensively investigated in the recent literature aiming at maximising Vitamin C retention throughout the whole product lifecycle, from farm to fork. In such an integrated approach, it is important to separately study the effect of each preservation step and mathematically describe the impact of the prevailing factors on Vitamin C stability, so as to be able to optimise the processing/storage phase. In this context, alternative mathematical approaches have been applied, including more sophisticated ones that incorporate parameter uncertainties, with the ultimate goal of providing more realistic predictions.

Effect of Osmotic Pretreatment Combined with Vacuum Impregnation or High Pressure on the Water Diffusion Coefficients of Convection Drying: Case Study on Apples

The paper presents water diffusion coefficients as providing a significant contribution to the creation of a comprehensive database and knowledge of weight variation during the drying process of raw plant materials that is used for modelling the technological process and designing innovative products. Dehydration is one of the most widely used methods for improving the stability and durability of fruit and vegetables because it reduces water activity and microbial activity, and minimises the physical and chemical changes during storage. The considerable impact of pressure on heat exchange and weight during the convection drying process of osmotically pretreated apples is demonstrated. The course of the drying curves and the drying rate is determined by the use of pressures of 0.02 and 500 MPa. Varied pressure applied during osmotic impregnation significantly influences the value of the diffusion coefficient: the average determined for the entire course of the drying curve and the average determined in the intervals of the reduced water content. The lowest values of the average water diffusion coefficient are obtained for apples preboiled under overpressure conditions and, at the same time, the determined diffusion coefficients in the water content are characterised on the drying curve by a clearly decreasing course until the reduced water content reaches approximately 0.2.

Edible coatings as osmotic dehydration pretreatment in nutrient-enhanced fruit or vegetable snacks development: A review

Edible coatings (ECs) are thin layers applied on food to protect it and improve quality. They are made from bio-based materials such as polysaccharides, proteins, lipids, or their composites. The incorporation of functional agents, such as bioactive compounds, vitamins, or antimicrobials into the EC, has been investigated to control the shelf life of many food products from horticulture ones to processed food. Osmotic dehydration (OD) as a mild technology may also positively impact the availability of innovative fruit snacks and consequently influence consumer health. Combination of the EC with the OD aims to remove water through the semipermeable membrane while limiting the transfer of solutes from the dehydrated tissue and in the opposite direction from the osmotic solution to the food. The development trend of the snack market is expanding, especially with health-promoting properties. Consumers pay increasing attention to quality of food and its beneficial effects on health. This review attempts to provide the advancement of recent studies on the application of the EC before the OD of different fresh or fresh-cut fruit and vegetables. A fundamental theory related to the methodology of creating the EC, their composition, and the influence on the physicochemical properties of products that are osmo-dehydrated to a medium water content or additionally dried to a low water content have been described. Efforts have been exerted to introduce hydrocolloids used in the production of the EC, including new sources of biopolymers such as agricultural waste and by-products. The perspectives of using ECs in the technology of producing pro-healthy snacks are emphasized.

Osmotic dehydration: More than water loss and solid gain

The immersion of food in a hypertonic solution results in an osmotic dehydration process (OD) with the loss of water (WL) from the food to the solution and the gain of solids from the solution (SG) by the food. For this reason, OD is commonly used to produce semi-dehydrated or enriched foods by incorporation. Although the most of OD studies are focused on the WL and SG processes, many publications addresses the physicochemical and nutritional changes resulting from OD in the food matrix and in the osmotic solution. Such changes must be handled in order to improve the quality of the product. This work is a compilation of publications with this approach.

Structure and Applications of Pectin in Food, Biomedical, and Pharmaceutical Industry: A Review

Pectin is a biocompatible polysaccharide with intrinsic biological activity, which may exhibit different structures depending on its source or extraction method. The extraction of pectin from various industrial by-products presents itself as a green option for the valorization of agro-industrial residues by producing a high commercial value product. Pectin is susceptible to physical, chemical, and/or enzymatic changes. The numerous functional groups present in its structure can stimulate different functionalities, and certain modifications can enable pectin for countless applications in food, agriculture, drugs, and biomedicine. It is currently a trend to use pectin to produce edible coating to protect foodstuff, antimicrobial bio-based films, nanoparticles, healing agents, and cancer treatment. Advances in methodology, use of different sources of extraction, and knowledge about structural modification have significantly expanded the properties, yields, and applications of this polysaccharide. Recently, structurally modified pectin has shown better functional properties and bioactivities than the native one. In addition, pectin can be used in conjunction with a wide variety of biopolymers with differentiated properties and specific functionalities. In this context, this review presents the structural characteristics and properties of pectin and information on the modification of this polysaccharide, its respective applications, perspectives, and future challenges.

Chitosan Nanoparticles as a Promising Nanomaterial for Encapsulation of Pomegranate (Punica granatum L.) Peel Extract as a Natural Source of Antioxidants

The encapsulation of pomegranate peel extract (PPE) in chitosan nanoparticles (CSNPs) is an advantageous strategy to protect sensitive constituents of the extract. This study was aimed to develop PPE-loaded CSNPs and characterize their physical, structural morphology, antioxidant and antimicrobial properties. Spherical NPs were successfully synthesized with a mean diameter of 174–898 nm, a zeta potential (ZP) of +3 – +36 mV, an encapsulation efficiency (EE) of 26–70%, and a loading capacity (LC) of 14–21% depending on their loaded extract concentrations. Based on these results, CSNPs with chitosan:PPE ratio of 1:0.50 (w/w) exhibited good physical stability (ZP = 27 mV), the highest loading (LC = 20%) and desirable encapsulation efficiency (EE = 51%), and thus, selected as optimally loaded NPs. The FTIR analysis of PPE-CSNPs demonstrated no spectral changes indicating no possible chemical interaction between the PPE and CSNPs, which confirms that the PPE was physically entrapped within NPs. Moreover, FTIR spectra of pure PPE showed specific absorption bands (at 3293–3450 cm⁻¹) attributed to the incidence of phenolic compounds, such as tannic acid, ellagic acid and gallic acid. Total phenolic content (TPC) and antioxidant analysis of selected CSNPs revealed that the encapsulated NPs had significantly lower TPC and antioxidant activity than those of pure PPE, indicating that CSNPs successfully preserved PPE from rapid release during the measurements. Antibacterial tests indicated that pure PPE and PPE-loaded CSNPs effectively retarded the growth of Gram-positive S. aureus with a minimum inhibitory concentration (MIC) of 0.27 and 1.1 mg/mL, respectively. Whereas Gram-negative E. coli, due to its protective cell membrane, was not retarded by pure PPE and PPE-CSNPs at the MIC values tested in this study. Gas chromatography-mass spectroscopy analysis confirmed the incidence of various phytochemicals, including phenolic compounds, fatty acids, and furfurals, with possible antioxidant or antimicrobial properties. Overall, CSNPs can be regarded as suitable nanomaterials for the protection and controlled delivery of natural antioxidants/antimicrobials, such as PPE in food packaging applications.

Effect of Ethanol and Ultrasound Pretreatments on Pineapple Convective Drying

Research background

Drying represents a viable unit operation for the preservation of food. Convective drying is the most used method for plant materials. However, it can result in negative changes in food nutrient composition, and other quality parameters, besides requiring high energy consumption. Pretreatments can represent an alternative to minimise these negative aspects of dried materials. This work aims to evaluate the use of ethanol and ultrasound before pineapple convective drying and its effect on the product´s colour, water activity, ascorbic acid and total carotenoid contents.

Experimental approach

For the pretreatment step, fruit samples were immersed in ethanol solutions of different volume fractions, and experiments were carried out for 10 min with and without using ultrasound (25 kHz). Fruit samples were dried at 60 ºC. A control group (without the pretreatment step) was also dried under the same condition. Semi-theoretical models were used for drying data fitting, and the diffusional model was used to describe the moisture transfer and calculate the effective diffusivity. Water activity, ascorbic acid, total carotenoids and colour analyses were performed.

Results and conclusions

The combination of ethanol and ultrasound as a pretreatment reduced the drying time of pineapple. Higher effective moisture diffusivities were obtained when ethanol and ultrasound were applied before drying. The two-term exponential model presented the best fit for drying experimental data. The dried samples had a darker colour than the fresh sample. The pretreatment with ethanol resulted in increased retention of the studied bioactive components. The satisfactory results of this study represent an improvement in the drying process.

Novelty and scientific contribution

Ultrasound and ethanol as a pretreatment to convective drying are promising. However, each food matrix has a typical structure and composition. Therefore, the application of the pretreatment in other products or using other conditions is still necessary to deeply understand and explain their effect on the process and the quality of the dried products.

Quality Characteristics of Semi-Moist Apricot-Cornflakes: Effect of Different Composite Coating Application and Storage Time

The effect of different composite coatings on quality of semi-moist apricot cubes mixed with cornflakes was investigated during 180 days of storage. The apricot cubes were osmotically dehydrated (OD) and coated before hot-air drying (HAD) at 60 °C. Chitosan-bees wax (CBW) and whey protein isolate-bees wax-oleic acid (WPI-BW-OA) coatings were applied after HAD and the samples were added to cornflakes. Application of OD and pectin-ascorbic acid (Pec-AA) coating (prior to HAD) and WPI-BW-OA coating (after HAD) led to significant retention of total phenol compounds, β-carotene and antioxidant activity in apricot cubes compared to uncoated and CBW-coated samples. WPI-BW-OA-coated samples gave significantly higher L* values (lighter color) and b* values (more creamy or yellowish color) and lower a* values (less reddish color) and browning values than control followed by CBW-coated apricots at any time of storage (p < 0.05). The rate of apricot moisture loss and cornflakes moisture gain was higher in uncoated apricot cubes, followed by CBW- and WPI-BW-OA-coated samples. Application of WPI-BW-OA coating was effective in retaining the crispness measured by lower firmness (Fmax) values in cornflakes upon storage. Based on the obtained results, WPI-BW-OA coating allowed effectively preserving the quality characteristics of semi-moist apricot cubes and cornflakes components in the mixed state.

Active Polypropylene-Based Films Incorporating Combined Antioxidants and Antimicrobials: Preparation and Characterization

Development of polypropylene (PP) films incorporating antioxidant-antimicrobial agents can inhibit microbial growth and reduce undesirable deteriorating reactions and can preserve the quality of food. This study was aimed to use a combination of sorbic acid (SA), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) to provide a synergistic effect at their reduced concentrations. A Combination of the additives was more effective in enhancing mechanical properties compared to their single state in film composition. The PP-2%SA-3%BHA film (T₃) had the highest tensile strength (17.9 MPa) and the lowest elongation at break (7.1%) than other films. The fourier-transform infrared (FTIR) proposed physical mixing of active additives within PP-matrix. Scanning electron microscopy showed uniform dispersion of the additives in PP-2%SA-1%BHT-1%BHA film (T₄) compared to others. BHT containing films decreased the storage and loss moduli leading to weakening of film viscoelastic behaviour and reducing film melting point. The prepared active films showed higher antioxidant activity than control PP-film following an order of T₄ > T₂ > T₃ corresponding to DPPH radical scavenging values of 89.1, 83.4 and 79.1%, respectively. All active films inhibited gram-negative and gram-positive bacteria growth. The results of this study indicated that the prepared active films possess desirable mechanical, thermal, antioxidant and antimicrobial properties enabling their use in food packaging.

Physicochemical, Thermal and Rheological Properties of Pectin Extracted from Sugar Beet Pulp Using Subcritical Water Extraction Process

The objective of this study was to characterize the properties of pectin extracted from sugar beet pulp using subcritical water (SWE) as compared to conventional extraction (CE). The research involved advanced modeling using response surface methodology and optimization of operational parameters. The optimal conditions for maximum yield of pectin for SWE and CE methods were determined by the central composite design. The optimum conditions of CE were the temperature of 90 °C, time of 240 min, pH of 1, and pectin recovery yield of 20.8%. The optimal SWE conditions were liquid-to-solid (L/S) ratio of 30% (v/w) at temperature of 130 °C for 20 min, which resulted in a comparable yield of 20.7%. The effect of obtained pectins on viscoamylograph pasting and DSC thermal parameters of corn starch was evaluated. The contents of galacturonic acid, degree of methylation, acetylation, and ferulic acid content were higher in the pectin extracted by SWE, while the molecular weight was lower. Similar chemical groups were characterized by FTIR in both SWE and CE pectins. Color attributes of both pectins were similar. Solutions of pectins at lower concentrations displayed nearly Newtonian behavior. The addition of both pectins to corn starch decreased pasting and DSC gelatinization parameters, but increased ΔH. The results offered a promising scalable approach to convert the beet waste to pectin as a value-added product using SWE with improved pectin properties.

Current Applications of Ultrasound in Fruit and Vegetables Osmotic Dehydration Processes

Ultrasound (US) is a promising technology, which can be used to improve the efficacy of the processes in food technology and the quality of final product. US technique is used, e.g., to support mass and heat transfer processes, such as osmotic dehydration, drying and freezing, as well as extraction, crystallization, emulsification, filtration, etc. Osmotic dehydration (OD) is a well-known process applied in food processing; however, improvements are required due to the long duration of the process. Therefore, many recent studies focus on the development of OD combined with sonication as a pretreatment method and support during the OD process. The article describes the mechanism of the OD process as well as those of US and changes in microstructure caused by sonication. Furthermore, it focuses on current applications of US in fruits and vegetables OD processes, comparison of ultrasound-assisted osmotic dehydration to sonication treatment and synergic effect of US and other innovative technics/treatments in OD (such as innovative osmotic solutions, blanching, pulsed electric field, reduced pressure and edible coatings). Additionally, the physical and functional properties of tissue subjected to ultrasound pretreatment before OD as well as ultrasound-assisted osmotic dehydration are described.

Effects of Osmotic Dehydration on the Hot Air Drying of Apricot Halves: Drying Kinetics, Mass Transfer, and Shrinkage

This study aimed to determine the effects of osmotic dehydration on the kinetics of hot air drying of apricot halves under conditions that were similar to the industrial ones. The osmotic process was performed in a sucrose solution at 40 and 60 °C and concentrations of 50% and 65%. As expected increased temperatures and concentrations of the solution resulted in increased water loss, solid gain and shrinkage. The kinetics of osmotic dehydration were well described by the Peleg model. The effective diffusivity of water 5.50–7.387 × 10−9 m2/s and solute 8.315 × 10−10–1.113 × 10−9 m2/s was calculated for osmotic dehydration. Hot air drying was carried out at 40, 50, and 60 °C with air flow velocities of 1.0 m/s and 1.5 m/s. The drying time shortened with higher temperature and air velocity. The calculated effective diffusion of water was from 3.002 × 10−10 m2/s to 1.970 × 10−9 m2/s. The activation energy was sensitive to selected air temperatures, so greater air velocity resulted in greater activation energy: 46.379–51.514 kJ/mol, and with the osmotic pretreatment, it decreased to 35.216–46.469 kJ/mol. Osmotic dehydration reduced the effective diffusivity of water during the hot air drying process. It also resulted in smaller shrinkage of apricot halves in the hot air drying process.

Impact of Innovative Technologies on the Content of Vitamin C and Its Bioavailability from Processed Fruit and Vegetable Products

Nowadays, thermal treatments are used for extending the shelf-life of vegetable and fruit products by inactivating microorganisms and enzymes. On the other hand, heat treatments often induce undesirable changes in the quality of the final product, e.g., losses of nutrients, color alterations, changes in flavor, and smell. Therefore, the food industry is opening up to new technologies that are less aggressive than thermal treatment to avoid the negative effects of thermal pasteurization. Non-thermal processing technologies have been developed during the last decades as an alternative to thermal food preservation. Processing changes the structure of fruit and vegetables, and hence the bioavailability of the nutrients contained in them. In this review, special attention has been devoted to the effects of modern technologies of fruit and vegetable processing, such as minimal processing (MPFV), high-pressure processing (HPP), high-pressure homogenization (HPH), ultrasounds (US), pulsed electric fields (PEF), on the stability and bioavailability of vitamin C.

Physicochemical properties and sensory acceptability of beetroot chips pre-treated by osmotic dehydration and ultrasound

Abstract Red beet (or beetroot) is highly nutritious and can be preserved by drying, in order to avoid wastage, to take advantage of crop surpluses, and to add value during the off-season. The objective of this study was to evaluate the effects of osmotic dehydration (OD) and ultrasound (US) pre-treatments on the nutritional quality and sensory characteristics of dried beetroot chips. The kinetics of moisture loss during OD and US were predicted by fitting the experimental data with thin-layer models. The physicochemical parameters (moisture, protein, lipid, carbohydrate, energy, ash, sodium and nitrate) and sensory properties (affective preference-ordering and acceptance test) were determined. Correlations between the treatments and the sensory acceptability evaluated by consumer’s perceptions were performed by applying unsupervised chemometric techniques (Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA)). The two-term exponential model provided the best fit for the experimental drying data. The US treatment promoted a higher drying rate and lower lipid, ash and energy values, while the OD process resulted in higher ash and sodium values. Multivariate analysis revealed that the US and OD treatments improved the sensory properties of the beetroot chips. The US was more efficient pre-treatment for producing beet chips due to its leads a significant reduction on drying time and intermediate level of sensory preference.

The effect of osmotic dehydration conditions on the calcium content in plant matrice

Osmotic dehydration is used as a pre-treatment before drying. This process can also be used as a method of modulation of the sensory values of plant components and fortifying them with selected components. The aim of this study was to examine the effect of osmotic dehydration as a method of pumpkin flesh 'Melon Yellow' (Cucurbita maxima) fortification with calcium. The studies showed for the first time that by selecting the appropriate process conditions it is possible to significantly increase the level of calcium in plant matrice. The highest calcium content was found in the pumpkin pulp dehydrated in 50% xylitol and inulin solutions with a calcium carbonate (5%), where the process was conducted for 120 min at 30 °C (1,380.4 and 1,328.4 mg Ca/100 g). Therefore, study has shown an innovative application of the osmotic dehydration process for the design of food with health-promoting properties, including for those at risk of osteoporosis.

Edible and Functionalized Films/Coatings—Performances and Perspectives

In recent years, food packaging has evolved from an inert and polluting waste that remains after using the product toward an active item that can be consumed along with the food it contains. Edible films and coatings represent a healthy alternative to classic food packaging. Therefore, a significant number of studies have focused on the development of biodegradable enveloping materials based on biopolymers. Animal and vegetal proteins, starch, and chitosan from different sources have been used to prepare adequate packaging for perishable food. Moreover, these edible layers have the ability to carry different active substances such as essential oils—plant extracts containing polyphenols—which bring them considerable antioxidant and antimicrobial activity. This review presents the latest updates on the use of edible films/coatings with different compositions with a focus on natural compounds from plants, and it also includes an assessment of their mechanical and physicochemical features. The plant compounds are essential in many cases for considerable improvement of the organoleptic qualities of embedded food, since they protect the food from different aggressive pathogens. Moreover, some of these useful compounds can be extracted from waste such as pomace, peels etc., which contributes to the sustainable development of this industry.