The Influence of Different Air-Drying Conditions on Bioactive Compounds and Antioxidant Activity of Berries

Role of Phytonutrients in the Prevention and Treatment of Chronic Diseases: A Concrete Review

Delving into the intricate role of phytonutrients is paramount to effectively preventing and treating chronic diseases. Phytonutrients are "plant-based nutrients" that positively affect human health. Phytonutrients perform primary therapeutic functions in the management and treatment of various diseases. It is reported that different types of pathogenesis occur due to the excessive production of oxidants (reactive nitrogen species and reactive oxygen species). The literature shows that a higher intake of fruits, vegetables, and other plant-based food is inversely related to treating different chronic diseases. Due to many phytonutrients (antioxidants) in fruits, vegetables, and other medicinal plants, they are considered major therapeutic agents for various diseases. The main purpose of this review is to summarize the major phytonutrients involved in preventing and treating diseases. Fourteen major phytonutrients are discussed in this review, such as polyphenols, anthocyanin, resveratrol, phytosterol (stigmasterol), flavonoids, isoflavonoids, limonoids, terpenoids, carotenoids, lycopene, quercetin, phytoestrogens, glucosinolates, and probiotics, which are well-known for their beneficial effects on the human body and treatment of different pathological conditions. It is concluded that phytonutrients play a major role in the prevention and treatment of diabetes mellitus, obesity, hypertension, cardiovascular disorders, other types of cancers, neurological disorders, age-related diseases, and inflammatory disorders and are also involved in various biological activities.

Effect of dipping pre-treatments and drying methods on Aronia melanocarpa quality

This study examined the impact of different dipping pre-treatments (PO: potassium carbonate-olive oil emulsion, HW: hot water) and drying methods (sun, oven, hot air, and freeze) on aronia berry quality. Freeze-drying showed the highest process yield (29.07%-29.43%), while sun-drying had the lowest (24.60%-25.74%). PO pre-treatment showed superior moisture and water activity reductions across all drying methods. Notably, it enhanced carotenoid levels (PO: 399.5, HW: 371.4 mg BCE/kg), antioxidant activity (PO: 9602.8, HW: 9403.3 mg TE/kg), total phenolics (PO: 38176.5, HW: 34804.0 mg GAE/kg) and flavonoids (PO: 6537.1, HW: 6141.5 mg CE/kg) during freeze-drying. Additionally, PO-treated samples exhibited superior rehydration properties, with a ratio of 293.32% and a 1.01 g/g capacity. On the other hand, HW pre-treatment increased ascorbic acid levels (PO: 377.0, HW: 391.7 mg/kg). The highest quality dried aronia berries are generally observed in PO-treated samples, especially in freeze drying, followed by hot-air, oven, and sun drying processes.

Effects of thermal processing on natural antioxidants in fruits and vegetables

Research on the content of polyphenolic compounds in fruits and vegetables, the extraction of bioactive compounds, and the study of their impact on the human body has received growing attention in recent years. This is due to the great interest in bioactive compounds and their health benefits, resulting in increased market demand for natural foods. Bioactive compounds from plants are generally categorized as natural antioxidants with health benefits such as anti-inflammatory, antioxidant, anti-diabetic, anti-carcinogenic, etc. Thermal processing has been used in the food sector for a long history. Implementing different thermal processing methods could be essential in retaining the quality of the natural antioxidant compounds in plant-based foods. A comprehensive review is presented on the effects of thermal blanching (i.e., hot water, steam, superheated steam impingement, ohmic and microwave blanching), pasteurization, and sterilization and drying technologies on natural antioxidants in fruits and vegetables.

Black bean (Phaseolus vulgaris L. cv. "Tolosa") polyphenolic composition through cooking and in vitro digestion

In this study, five different black bean (Phaseolus vulgaris L. cv. Tolosa) populations cultivated in different geographical areas including Oiartzun, Andoain, Azkoitia, San Esteban and Amasa Villabona, were studied and their polyphenolic content was determined. Two food products were prepared from the five different bean populations, cooked "Tolosa" beans and a hummus made with "Tolosa" cooked beans. Moreover, the variations of total polyphenol content (TPC), total anthocyanin content (TAC) and free radical scavenging activity by the 1,1-diphenyl-1-picrylhydrazyl (DPPH) method were analyzed for raw beans, cooked beans, and "Tolosa" beans hummus. Polyphenolic detailed composition was determined by means of HPLC-MS-QTOF analysis. The "Tolosa" bean population richest in polyphenols was selected in order to study the effect of in vitro digestion on the polyphenolic content and antioxidant effect and the degradation of the main anthocyanins was followed during the in vitro digestion. Finally, the effect of the different phases of digestion on the cytotoxicity in Caco-2 cells was determined. The results suggest that cooking "Tolosa" black beans results in an increase in the bioaccessibility of polyphenols and their antioxidant activity, which, additionally has a positive effect on Caco-2 intestinal cell viability.

Quality Characteristics of Raspberry Fruits from Dormancy Plants and Their Feasibility as Food Ingredients

The raspberry (Rubus idaeus L.) is a soft red fruit consumed worldwide due to its bitter-sweet taste and phenolics-associated health benefits. During plant dormancy, raspberry fruits are discarded. However, this work hypothesised that these fruits have the chemical quality to be valorised, which would mitigate their waste if adequately stabilised. This can be achieved by drying. The Pacific Deluxe and Versailles varieties were dried by freeze- and convective-drying (30 °C and 40 °C). The freeze-dried fruits preserved their colour, drupelets structure, and phenolic content. Convective-drying promoted a significant fruit darkening, which was more evident at 30 °C due to the longer drying process, and a loss of drupelets structure. Both temperatures promoted a similar decrease in phenolic content, as determined by HPLC, although the ABTS●+ antioxidant activity at 40 °C was lower (IC50 = 9 compared to 13 μg AAE/mg dry weight). To incorporate dried raspberries into muffin formulations, while keeping their red colour, it was necessary to change the raising agent from sodium bicarbonate to baker's yeast. Sensory analysis by a non-trained panel revealed good acceptance, showing that fresh or dried raspberry fruits from dormancy had suitable characteristics for use as food ingredients.

Infrared-assisted spouted bed drying of Chinese yam cubes: effect of constant and variable temperature drying processes on drying behavior, uniformity, and quality attributes

BACKGROUND

Infrared-assisted spouted bed drying (IRSBD) is an innovative hybrid drying technology based on infrared drying and spouted bed drying, which has the advantages of higher drying efficiency and better uniformity. Temperature is an important process parameter that affects drying characteristics and product quality. Considering the overall quality of the product, drying at a constant temperature may not be the best solution. However, there is a lack of research on dynamically varying drying schemes. In this study, the effects of constant and variable temperature drying processes on the drying characteristics, uniformity, energy consumption, and quality of Chinese yams were evaluated.

RESULTS

The shortest drying time and lowest energy consumption were obtained by IRSBD at 70 °C, followed by staged rising temperature drying (SRTD). However, SRTD achieved the best drying uniformity. The Peleg model could describe the dehydration kinetics of dried yams well (R²  > 0.99). A high drying temperature (70 °C) favored the preservation of bioactive compounds (polyphenols and flavonoids) and gave the best antioxidant activity and equilibrium rehydration ratio of dried yams but resulted in poor color. Samples dried with SRTD showed comparable good antioxidant activity and better color than those dried at 70 °C.

CONCLUSION

A reasonable variable temperature drying scheme using IRSBD is considered to be better when considering the drying performance and overall quality of the products. © 2022 Society of Chemical Industry.

Polyphenol and Flavonoid Stability of Wild Blueberry (Sideroxylon mascatense) during Air- and Freeze-Drying and Storage Stability as a Function of Temperature

Būt (Sideroxylon mascatense) is an indigenous wild blueberry found in Oman. It has a very short season and is commonly preserved by drying. The aims of this study were to determine the physico-chemical characteristics and stability of phytochemicals (i.e., polyphenols and flavonoids) in the berries during drying (i.e., freeze-drying at -40 °C and air-drying at 60 and 90 °C) and the polyphenol stability of the dried berries as a function of storage temperature (i.e., 90, 70, 60, 40, 20, and -20 °C). The moisture content of fresh berry flesh was 64.5 g/100 g sample (wet basis). The crude protein and fat contents were higher in the seeds than in the flesh. Glucose and fructose were the main sugars and their concentrations were highest in the sample air-dried at 60 °C. The initial total polyphenol content (TPC) and total flavonoid content (TFC) of the flesh were 2.009 mg gallic acid equivalent (GAE)/g dry-solids and 0.199 mg catechin equivalent (CE)/g dry-solids, respectively. The samples air-dried at 90 °C and freeze-dried at -40 °C had higher TPC (i.e., 2.638 mg GAE/g dry-solids) and TFC (i.e., 0.395 mg CE/g dry-solids), respectively. There was a significant difference between the TPC and TFC of fresh and dried wild berries (p < 0.05). The freeze-dried wild berries retained a high TPC compared to the air-dried samples. The polyphenol storage stability of freeze-dried wild berries at different storage temperatures showed two phases: an initial release phase followed by a decay phase. The polyphenol storage stability was modeled using the Peleg model and the kinetic parameters were correlated with the storage temperature.

Effect of Storage and Drying Treatments on Antioxidant Activity and Phenolic Composition of Lemon and Clementine Peel Extracts

Obtaining polyphenols from horticultural waste is an emerging trend that enables the valorization of resources and the recovery of value-added compounds. However, a pivotal point in the exploitation of these natural extracts is the assessment of their chemical stability. Hence, this study evaluates the effect of temperature storage (20 and -20 °C) and drying methods on the phenolic composition and antioxidant activity of clementine and lemon peel extracts, applying HPLC-DAD-MS, spectrophotometric methods, and chemometric tools. Vacuum-drying treatment at 60 °C proved to be rather suitable for retaining the highest antioxidant activity and the hesperidin, ferulic, and coumaric contents in clementine peel extracts. Lemon extracts showed an increase in phenolic acids after oven-drying at 40 °C, while hesperidin and rutin were sustained better at 60 °C. Hydroethanolic extracts stored for 90 days preserved antioxidant activity and showed an increase in the total phenolic and flavonoid contents in lemon peels, unlike in clementine peels. Additionally, more than 50% of the initial concentration was maintained up to 51 days, highlighting a half-life time of 71 days for hesperidin in lemon peels. Temperature was not significant in the preservation of the polyphenols evaluated, except for in rutin and gallic acid, thus, the extracts could be kept at 20 °C.

Varietal Effect on Composition and Digestibility of Seedless Table Grapes (Vitis vinifera L.) under In Vitro Conditions

Grapes are one of the richest sources of polyphenols in the Mediterranean diet and, therefore, a very good source of antioxidants in the human diet. For practical reasons, in recent years the market for seedless grape varieties has grown exponentially. These varieties are not well characterized yet, and therefore it is necessary to study the changes in composition that these new varieties bring in. Likewise, the effect of digestion on the bioavailability of polyphenols in foods of plant origin is well known, which, consequently, will also affect antioxidant activity and, in general, bioactivity. In this work, we studied the effect of the grape variety on the initial grape composition and on the absorbable fraction, as it would reach the intestine after in vitro digestion. Our results showed that black and red varieties have great potential for increasing the antioxidant content of the diet. Additionally, we have concluded that all polyphenols, with the exception of flavanols, see their bioavailable fraction diminished under in vitro conditions.

Solid-State Fermentation of Sorghum by Aspergillus oryzae and Aspergillus niger: Effects on Tannin Content, Phenolic Profile, and Antioxidant Activity

Sorghum contains antioxidants such as tannins. However, these are considered antinutritional factors since they are responsible for the low digestibility of proteins and carbohydrates. Nevertheless, these can be extracted by solid-state fermentation (SSF). Therefore, this study aimed to evaluate the effects of SSF from Aspergillus oryzae and Aspergillus niger Aa210 on the tannin contents, phenolic profiles determined by HPLC-MS, and antioxidant activities (ABTS, DPPH, and FRAP) of two genotypes of sorghum. The results showed that with SSF by A. niger Aa210, a higher tannin content was obtained, with yields of 70-84% in hydrolyzable tannins (HT) and 33-49% in condensed tannins (CT), while with SSF by A. oryzae the content of HT decreased by 2-3% and that of CT decreased by 6-23%. The extracts fermented by A. niger at 72 and 84 h exhibited a higher antioxidant activity. In the extracts, 21 polyphenols were identified, such as procyanidins, (+)-catechin, (-)-epicatechin, scutellarein, arbutin, and eriodictyol, among others. Therefore, SSF by A. niger was an efficient process for the release of phenolic compounds that can be used as antioxidants in different food products. It is also possible to improve the bioavailability of nutrients in sorghum through SSF. However, more studies are required.

Cider apple pomace as a source of nutrients: Evaluation of the polyphenolic profile, antioxidant and fiber properties after drying process at different temperatures

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Influence of cider apple pomace drying temperature was studied.

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Temperature affected drying kinetics and antioxidant and dietary fibre properties.

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Antioxidant properties were best preserved when drying in the range of 80–100 °C.

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The best properties of alcohol insoluble residue were found when drying at 40–60 °C.

Apple pomace, the by-product of the cider industry, contains a high content of antioxidant compounds and dietary fiber. Drying would allow its preservation for a later use. The aim of this study was to evaluate the effect of the drying temperature on the drying kinetics, antioxidant properties and the fiber characteristics. For this, drying experiments were performed at different temperatures (40–120 °C). The increase in temperature enhanced the drying rate, as was shown by the effective diffusivity and mass transfer coefficient identified by modelling. The influence of temperature was quantified through the activation energy (38.21 kJ/mol). Regarding the retention of antioxidant properties, the best results were found at 80–100 °C while 40–60 °C was the best temperature range for the fiber characteristics. Therefore, 80 °C could be an adequate temperature for drying of cider apple pomace, as it represents a good balance between kinetics, and antioxidant and fiber properties.

The role of emerging technologies in the dehydration of berries: Quality, bioactive compounds, and shelf life

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Berries comprise essential nutrients necessary for healthy living.

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Convective, vacuum, microwave, and freeze-drying are the most common methods.

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Pre-treatments improve permeability, accelerate drying, and inactivate oxidation.

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Combined methods are recommended to assure high quality of dehydrated berries.

Berries are among the fruits with the highest nutritional and commercial value. This paper reviews the conventional and emerging dehydration methods most commonly used as postharvest treatment and discusses their efficacy in maintaining and/or improving the nutritional and functional qualities of dried berries. The characteristics of the conventional methods (e.g., convective drying, freeze-drying, spray-drying, osmotic dehydration), their pre-treatments, their combination, and intermittent drying, as well as their potential disadvantages are discussed. The use of emerging dehydration techniques (e.g., electromagnetic radiation drying, explosion puffing drying, heat pump drying, low-pressure superheated steam drying, microwave drying) allows to improve the quality of the dried berries compared to conventional techniques, in addition to reducing drying times, increasing drying speed and energy efficiency. Finally, the use of pre-treatments and the combination of technologies can enhance the quality of the final product as a result of the improvement in the effectiveness of the dehydration process.

Development of blueberry (Vaccinium corymbosum L.) waste powder as a potential food ingredient with functional properties

Salta province, northwestern Argentina, produces blueberries for export and discards fruits with a potential quantity of bioactive compounds. These bioactive compounds have health-promoting properties that prevent or delay the appearance of chronic diseases. This study aimed to formulate blueberry microcapsules using discarded fruit, to determine and evaluate the effect of spray-drying and lyophilization on the bioactive compounds and their physical properties. Fourteen capsule prototypes were obtained by applying a randomized full factorial design with two factors: type of drying and type of wall material. The former factor had two levels (spray-drying and lyophilization) and the latter had three levels, each with defined quantities to be used, namely maltodextrin (0%, 10%, 15%, and 30%), gum Arabic (0%, 10%, 15%, and 30%), and modified starch (0%, 10%, 15%, and 30%). Spray-drying, lyophilization, total polyphenols, anthocyanins, proanthocyanidins, antioxidant activity, and the physical properties of the microcapsules were analyzed using ANOVA, PCA, and cluster analysis. Results showed significant differences between the two processes (P < 0,05), with lyophilization being better at preserving bioactive compounds. The PCA test also showed a positive association between lyophilization and bioactive compounds, while spray-drying powders were related to negative characteristics, like moisture and water activity.

Effect of food processing on antioxidants, their bioavailability and potential relevance to human health

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Processing alters the amount, matrix interaction, and structure of antioxidants.

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It is not easy to dissociate processing effects from food matrix effects.

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It is still difficult to make general statements on the effects of processing on bioavailability.

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Facilitated release by heat, pressure, etc. contributes to increased bioaccessibility.

It has long been recognized that the antioxidants present in fresh plant materials may be very different to those we ingest via our foods. This is often due to the use of food processing strategies involving thermal/non-thermal treatments. Current research mostly focuses on determining what is present in vegetative starting materials; how this is altered during processing; how this influences activity in the gut and following uptake into bloodstream; and which in vivo physiological effects this may have on human body. Having a better understanding of these different steps and their importance in a health-and-nutrition-context will place us in a better position to breed for improved crop varieties and to advise the food industry on how to optimize processing strategies to enhance biochemical composition of processed foods. This review provides an overview of what is currently known about the influence which food processing treatments can have on antioxidants and gives some pointers as to their potential relevance.

Effects of Processing and Storage Conditions on Functional Properties of Powdered Blueberry Pomace

Promoting a circular economy through valorisation of food processing waste into functional ingredients is a challenge today. The combination of hot air drying with milling is a cheap and highly available option for obtaining powdered products from blueberry pomace, a residue with a large amount of fibre and a high proportion of polyphenols from the fruit. The objective of this work was to analyse the effect of drying temperature (60 °C and 70 °C) and granulometry (coarse and fine) on physicochemical properties, including antioxidant properties and monomeric anthocyanins content. The potential prebiotic effect of blueberry pomace powders, as well as their water and oil interaction properties, were also assessed. Stability of physicochemical properties over 20 weeks of storage was also evaluated. Powders obtained showed a total fibre content higher than 30% with a good proportion between insoluble and soluble fractions and a high retention of monomeric anthocyanins from fresh pomace (75% at 60 °C and 66% at 70 °C). The powders showed good water interaction properties and interesting technological properties, such as solubility and hygroscopicity, which were not affected by differences in particle size. Stability of powders’ physicochemical properties was evidenced throughout the storage period.

Phenolic compounds in Nordic berry species and their application as potential natural food preservatives

An increasing demand for natural food preservatives is raised by consumers. For Nordic berry species, abundance of phenolic compounds and potent activities of anti-oxidation and anti-bacteria enables a great potential as food preservatives. This review provides a systematic examination of current literature on phenolic profiles, anti-oxidative and anti-bacterial activities of various extracts of Nordic berry species, as well as the impact of various structure features of phenolics on the bioactivities. Special attention is placed on exploitation of leaves of berry species and pomaces after juice-pressing as side-streams of berry production and processing. The current progress and challenges in application of Nordic berry species as food preservatives are discussed. To fully explore the potential application of Nordic berry species in food industry and especially to valorize the side-streams of berry cultivation (leaves) and juice-pressing industry (pomaces), it is crucial to obtain extracts and fractions with targeted phenolic composition, which have high food preserving efficacy and minimal impact on sensory qualities of food products.

A Red-Berry Mixture as a Nutraceutical: Detailed Composition and Neuronal Protective Effect

Recommendations towards increased consumption of fresh fruit and vegetables are well supported by epidemiological and clinical trials. However, in some specific cases, it is difficult to follow these recommendations and the use of nutraceuticals or, in the present work, a freeze-dried fruits mixture can be recommended in order to afford the optimal consumption of dietary polyphenols naturally present in fruits and vegetables. In this work we have carefully characterized a red-berry mixture in terms of polyphenol composition, encountering mainly anthocyanins, which account for a total of 2.8 mg/g as cyanidin-3-glucoside equivalents. Additionally, we have assayed the red-berry blend in a cell model of neurological damage by differentiating the cells and measuring the effect of red-berry polyphenols on cell viability and redox state by flow cytometry. The berry-fruit extract showed an inhibitory effect on differentiated SH-SY5Y ROS formation at a concentration as low as 250 µg/mL (33% inhibition). The results show the potential of this berry-fruit blend for its nutraceutical use in the prevention of the neurodegeneration associated with age or environmental agents.

Dietary Plant Polyphenols: Effects of Food Processing on Their Content and Bioavailability

Dietary plant polyphenols are natural bioactive compounds that are increasingly attracting the attention of food scientists and nutritionists because of their nutraceutical properties. In fact, many studies have shown that polyphenol-rich diets have protective effects against most chronic diseases. However, these health benefits are strongly related to both polyphenol content and bioavailability, which in turn depend on their origin, food matrix, processing, digestion, and cellular metabolism. Although most fruits and vegetables are valuable sources of polyphenols, they are not usually consumed raw. Instead, they go through some processing steps, either industrially or domestically (e.g., cooling, heating, drying, fermentation, etc.), that affect their content, bioaccessibility, and bioavailability. This review summarizes the status of knowledge on the possible (positive or negative) effects of commonly used food-processing techniques on phenolic compound content and bioavailability in fruits and vegetables. These effects depend on the plant type and applied processing parameters (type, duration, media, and intensity). This review attempts to shed light on the importance of more comprehensive dietary guidelines that consider the recommendations of processing parameters to take full advantage of phenolic compounds toward healthier foods.

Effect of Selected Drying Methods and Emerging Drying Intensification Technologies on the Quality of Dried Fruit: A Review

Drying is one of the oldest methods for food preservation that removes the water from fruit and makes it available for consumption throughout the year. Dried fruits can be produced by small- and large-scale processors, which makes them a very popular food among consumers and food manufacturers. The most frequent uses of drying technology include osmotic dehydration, vacuum drying, freeze-drying and different combinations of other drying technologies. However, drying may provoke undesirable changes with respect to physiochemical, sensory, nutritional and microbiological quality. Drying process energy efficiency and the quality of dried fruits are crucial factors in fruit drying. Recently, innovative technologies such as ultrasound, pulsed electric field and high pressure may be used as a pretreatment or in combination with traditional drying technologies for process intensification. This could result in quality improvements of dried fruits and enhanced efficiency and capacity of the production process, with a positive impact on environmental and economic benefits.

The Effect of Plant Additives on the Stability of Polyphenols in Dried Black Chokeberry (Aronia melanocarpa) Fruit

Chokeberry fruit exhibits a high level of pro-health potential, associated with a significant amount of polyphenol content and antioxidant activity. The fruit is easily perishable and therefore needs to be processed in short order to ensure its availability throughout the year. For this purpose, the fruit is dried, which has an impact on the preservation of bioactive components such as polyphenols. In the study, chokeberry fruit was influenced by a suspension of spices, including clove and cinnamon, and subsequently dried using the freeze-drying, convection, and microwave radiation methods. Freeze-drying was concluded to be the most desirable method of drying, which preserves the largest amount of polyphenols while soaking fruit in a suspension of cinnamon or cloves accelerated the loss of anthocyanins during the storage period. The obtained test results may constitute a valuable source of information for manufacturers in designing new products with increased pro-health potential, whose properties result from the high content of polyphenols and other plant additives.

Changes in the Quality of Old Apple Cultivars After Freeze-Drying

There are several thousand different cultivars of apple trees but only a limited number are cultivated on an industrial scale. Old cultivars can be useful, for example, in the processing industry due to their different composition. In many cases, they have higher organic acid content. The content of mineral components, colour, and polyphenols in the fruit of 7 old apple tree cultivars, growing in the Wolinski National Park, was studied. The changes that occurred in the fruit after freeze-drying were also evaluated. The trees from which the fruit was picked for analysis, despite the lack of chemical protection, were fruiting and the apples had only a few symptoms of damage caused by pests or diseases. The fruit was characterised by a high soluble solids content (14.4-16.4%), in which sugars and especially fructose dominated. The number of organic acids varied greatly and ranged from 0.27 (Oberlander Himbeerapfel) g to 1.07 g/100 g (Winter Goldparmane). The content of polyphenols in fresh apples ranged from 186 mg (Horneburger Pfannkuchenapfel) to 354 mg/100 g (Winter Goldparmane) and increased after freeze-drying from 666 mg (Weisser Winterkalvill) to 1486 mg/100 g (Winter Goldparmane). The dominant group of polyphenolic compounds was phenolic acid. The freeze-drying process caused unfavourable changes in the colour of the pulp. The fruits of Oberlander Himbeerapfel cultivar were most susceptible to these changes. However, the least darkened fruit of Horneburger Pfannkuchenapfel.

Influences of Postharvest Storage and Processing Techniques on Antioxidant and Nutraceutical Properties of Rubus idaeus L.: A Mini-Review

The growth of agricultural mechanization has promoted an increase in raspberry production, and for this reason, the best postharvest storage and processing techniques capable of maintaining the health beneficial properties of these perishable berry fruits have been widely studied. Indeed, raspberries are a rich source of bioactive chemical compounds (e.g., ellagitannins, anthocyanins, and ascorbic acid), but these can be altered by postharvest storage and processing techniques before consumption. Although there are clear differences in storage times and techniques, the content of bioactive chemical compounds is relatively stable with some minor changes in ascorbic acid or anthocyanin content during cold (5 °C) or frozen storage. In the literature, processing techniques such as juicing or drying have negatively affected the content of bioactive chemical compounds. Among drying techniques, hot air (oven) drying is the process that alters the content of bioactive chemical compounds the most. For this reason, new drying technologies such as microwave and heat pumps have been developed. These novel techniques are more successful in retaining bioactive chemical compounds with respect to conventional hot air drying. This mini-review surveys recent literature concerning the effects of postharvest storage and processing techniques on raspberry bioactive chemical compound content.

Conjugation of Pea Protein Isolate via Maillard-Driven Chemistry with Saccharide of Diverse Molecular Mass: Molecular Interactions Leading to Aggregation or Glycation

Diverse saccharides are effectively grafted to pea protein isolate (PPI) through Maillard-driven chemistry. The development of conjugates (glyco-PPI) was validated by ultraviolet-visible spectroscopy, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and size exclusion chromatography-high performance liquid chromatography. The impact of covalent conjugation on color development, structural modification, solubility, thermal stability, and volatiles of glycoprotein was examined. The protein solubility was improved, while its thermal stability seemed to be negatively influenced. The principle proposed involves Maillard-driven generation of the conjugates, which enhanced the surface hydrophilicity and unfolding of protein architecture of glyco-PPI. Additionally, both molecular mass and the grafted number of saccharides played a vital role in determining the solubility and thermal stability of glyco-PPI. Protein tends to denature at reaction conditions of 80 °C and pH 10.0, and its cross-linkage occurred in the aqueous system. The two potential routes of molecular interactions between PPI and saccharides were denaturation and glycation or self-cross-linkage. Flavor profile alteration of glycoprotein before and after conjugation was depicted, and relevant off-odors were quantified via headspace solid-phase microextraction gas chromatography-mass spectrometry. These outcomes could furnish valuable in-depth information for dictating functionalities of plant-based protein for food application.

The Quality of Freeze-Dried and Rehydrated Blueberries Depending on their Size and Preparation for Freeze-Drying

A significant increase in highbush blueberry plantings has been observed annually. However, there is a problem with the handling of fruit that does not meet the requirements for dessert berries. One of the methods to use the fruit is drying. The research was conducted in the Department of Horticulture at the West Pomeranian University of Technology in Szczecin. The fruit was harvested at a plantation specialising in the production of highbush blueberry from irrigated and non-irrigated plots. This study aimed to assess how cutting or pricking highbush blueberry fruit affects the duration of the sublimation drying process – freeze-drying. The biological value of fresh, freeze-dried, and rehydrated fruit was assessed. The amount of fruit left on bushes depended on the weather prevailing in the growing season, especially during the harvest period. The mass of fruit left on the bushes was approx. 1 to 2 t/ha. Although these fruits were small, they had a very high biological value. After freeze-drying and rehydration, the blueberry fruit retained their colour, high content of polyphenols and showed high antidiabetic activity and antioxidant capacity. The large fruit reached the moisture content of approx. 12%, which ensures safe storage and the appropriate texture, after 46 hours of drying, and the smaller fruit - after 32 hours. Fruit cutting or pricking reduced the drying time by half. Reducing this time decreased drying costs and increased biological value.

Chemometric analysis reveals influences of hot air drying on the degradation of polyphenols in red radish

Hot air drying is a commonly used technology in the preservation of red radish. This study was designed to investigate the correlations among total polyphenol content, total flavonoid content, antioxidant activities and polyphenol compounds in hot air dried red radish via chemometric analysis. UHPLC-QqQ-MS/MS analysis detected nine non-anthocyanin polyphenols and one anthocyanin in fresh and dried red radish samples, and found that hot air drying at 80 °C caused an increase in the p-coumaric acid and ferulic acid content of the red radish. The integral effect of hot air drying on the polyphenol profile of red radish was analyzed by principle component analysis, while sparse partial least squares-discriminant analysis showed that hot air drying induced changes mainly in the contents of poncirin, naringenin, phloetin and cyanidin-3-glucoside. These polyphenol degradations occurred as non-spontaneous and endothermic reactions during the hot air drying process, following first-order reaction kinetics.

Effect of hot air drying on the polyphenol profile of Hongjv (Citrus reticulata Blanco, CV. Hongjv) peel: A multivariate analysis

Hongjv peel (HP), a spice rich in polyphenols, is generally dried for its preservation. Hot air drying (HAD) at 50°C, 60°C, 70°C, and 80°C was performed in this study to dehydrate HP and it was found that the drying rate increased in line with the increase of HAD temperature. Absorbance analysis showed that HAD induced significant decreases in the total polyphenol content (TPC), total flavonoid content (TFC), and antioxidant activity of HP. Ultra performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis found 18 phytochemicals in the HP, including 11 flavonoids, 6 phenolic acids, and 1 triterpenoid, while multivariate analysis revealed that chlorogenic acid, hesperidin, naringenin, and phloretin in the HP were influenced mainly by HAD. HAD-induced degradations were non-spontaneous, endothermic reactions, consistent with the first-order reaction kinetics. In addition, the results suggest that HAD is more likely to degrade polyphenols that include an ester bond or glucoside. PRACTICAL APPLICATIONS: Among the various methods of preservation used to process spices, HAD is still the most effective. The polyphenol of HP possesses numerous health benefits, including being anti-oxidative, anti-inflammatory, anticancer, antiproliferative, and other qualities. This study provides a method through which to obtain insight into the effects of HAD on polyphenols in food, and indicates potential targets to increase the polyphenol content in HP.

New insights into Paeoniaceae used as medicinal plants in China

Paeoniaceae is an abundant germplasm resource with significant medicinal values in China, the principal medicinal components of which include paeoniflorin and paeonol. These compounds are typically obtained from air-dried root samples, which the use of freeze-drying as an alternative method has not been tested. Additionally, the presence of these two compounds in various wild Paeoniaceae species has not been previously explored, nor have the differences between various plant organs been fully evaluated. Here, freeze-drying and air-drying methods were compared to assess the changes in paeoniflorin and paeonol in root samples using ultra-performance liquid chromatography-mass spectrometer. The contents of these compounds in the roots, leaves, stems, and petals were then tested in freeze-dried materials. We also quantitatively detected the paeoniflorin and paeonol contents in the roots of 14 species collected from 20 natural habitats. Results indicated that the paeoniflorin content decreased under air-drying in comparison to freeze-drying, while the opposite trend was observed for paeonol. Our findings also demonstrated that the root xylem of species in Section Moutan, particularly Paeonia ostii, contains considerable paeonol and paeoniflorin and should thus be fully utilized as a medicinal resource. Furthermore, paeonol was mainly detected in the roots, while paeoniflorin was widely distributed in different organs; the highest content was in the leaf at the budding stage, suggesting that the leaves should be developed as a new paeoniflorin resource. Paeoniflorin contents were also found to be higher at earlier development stages. Based on the standards of the Chinese Pharmacopoeia, five species of Section Moutan and six species of Section Paeonia could be used as potential traditional Chinese medicinal resources. These findings of this study enhance our understanding of these two medicinal compounds and provide a foundation for the further development and utilization of Paeoniaceae as medicinal plant resources.

Convective Drying of Fresh and Frozen Raspberries and Change of Their Physical and Nutritive Properties

Raspberries are one of Serbia's best-known and most widely exported fruits. Due to market fluctuation, producers are looking for ways to preserve this fresh product. Drying is a widely accepted method for preserving berries, as is the case with freeze-drying. Hence, the aim was to evaluate convective drying as an alternative to freeze-drying due to better accessibility, simplicity, and cost-effectiveness of Polana raspberries and compare it to a freeze-drying. Three factors were in experimental design: air temperature (60, 70, and 80 °C), air velocity (0,5 and 1,5 m · s^-1), and state of a product (fresh and frozen). Success of drying was evaluated with several quality criteria: shrinkage (change of volume), color change, shape, content of L-ascorbic acid, total phenolic content, flavonoid content, anthocyanin content, and antioxidant activity. A considerable influence of convective drying on color changes was not observed, as ΔE was low for all samples. It was obvious that fresh raspberries had less physical changes than frozen ones. On average, convective drying reduced L-ascorbic acid content by 80.00-99.99%, but less than 60% for other biologically active compounds as compared to fresh raspberries. Convective dried Polana raspberry may be considered as a viable replacement for freeze-dried raspberries.

Multivariate Analysis Illuminates the Effects of Vacuum Drying on the Extractable and Nonextractable Polyphenols Profile of Loquat Fruit

The current study evaluated the effects of vacuum drying on the whole polyphenol profile of loquat fruit, including extractive and nonextractive polyphenols. Absorbance analysis determined that total polyphenol content and antioxidant levels were higher in loquat fruit vacuum dried at 140 °C than in loquat fruit vacuum dried at 70 °C. The results of ultra-HPLC-triple quadruple mass spectrum analysis showed that 15 phenolic acids and 17 flavonoids were found in dried loquat fruit. Multivariate integrative (MINT) sparse partial least square-discriminant analysis showed that vacuum drying affects the polyphenol profile of loquat fruit. Co-analysis of principal component analysis, partial least square-discriminant analysis, and orthometric partial least square-discriminant analysis revealed that vacuum drying mainly changed the content of chlorogenic acid, cryptochlorogenic acid, protocatechuic acid, phloretin, and hesperidin in loquat fruit. Chlorogenic acid (12.020 to 39.153 µg/g d.b. [dried base weight]), the main polyphenol in dried loquat fruit, was degraded to caffeic acid (0.028 to 2.365 µg/g d.b.) and protocatechuic acid (0.014 to 18.285 µg/g d.b.) during vacuum drying. Moreover, vacuum drying also induced the isomerization of chlorogenic acid into cryptochlorogenic acid (1.628 to 12.737 µg/g d.b.). These results might be used to develop dried loquat fruit with high levels of polyphenols and antioxidant activity. PRACTICAL APPLICATION: Interests in polyphenols of loquat fruit had increased greatly because of their possible role in health benefits. This work provided a holistic insight in the effects of vacuum drying on polyphenols profile of loquat fruit. Current results have contributed to the development of vacuum-drying method, which produced loquat fruit rich in polyphenols. Furthermore, it also suggested that multivariate analysis was a feasible method to reveal the important changes of polyphenols profile during food processing.