Bioactive Components, Applications, Extractions, and Health Benefits of Winery By-Products from a Circular Bioeconomy Perspective: A Review.

Significant waste streams produced during winemaking include winery by-products such as pomace, skins, leaves, stems, lees, and seeds. These waste by-products were frequently disposed of in the past, causing resource waste and environmental issues. However, interest has risen in valorizing vineyard by-products to tap into their latent potential and turn them into high-value products. Wine industry by-products serve as a potential economic interest, given that they are typically significant natural bioactive sources that may exhibit significant biological properties related to human wellness and health. This review emphasizes the significance of winery by-product valorization as a sustainable management resource and waste management method. The novelty of this review lies in its comprehensive analysis of the potential of winery by-products as a source of bioactive compounds, extraction techniques, health benefits, and applications in various sectors. Chemical components in winery by-products include bioactive substances, antioxidants, dietary fibers, organic acids, and proteins, all of which have important industrial and therapeutic applications. The bioactives from winery by-products act as antioxidant, antidiabetic, and anticancer agents that have proven potential health-promoting effects. Wineries can switch from a linear waste management pattern to a more sustainable and practical method by adopting a circular bioeconomy strategy. Consequently, the recovery of bioactive compounds that function as antioxidants and health-promoting agents could promote various industries concomitant within the circular economy.

Red Onion Peel Powder as a Functional Ingredient for Manufacturing Ricotta Cheese.

Onion (Allium cepa L.) is a vegetable widely cultivated and consumed due to its rich content in bioactive compounds. Red onion peel (ROP) powder, which is a by-product derived from the onion industry, has been attracting significant interest as a potential functional ingredient for improving the overall quality of foods. The present study explores the potential of ROP powder as a functional ingredient to improve the quality and nutritional value of whey cheese. Despite being frequently viewed as a food processing waste byproduct, ROP is a rich source of bioactive substances, including antioxidants, flavonoids, and dietary fiber, having antioxidant and antibacterial effects. The ROP extract exhibited high amounts of total polyphenols (119.69 ± 2.71 mg GAE/g dw) and antioxidant activity (82.35 ± 1.05%). Different quantities (1 and 3%) of ROP powder were added to cheese formulations, and the subsequent impact on the texture characteristics, sensory attributes, and phytochemical composition of the value-added cheeses was evaluated. The findings show that the addition of ROP powder improved the texture and the color of the cheeses, providing a visually appealing product. Additionally, adding the ROP powder significantly raised the amount of phytochemicals and antioxidant activity (17.08 ± 0.78 µmol TE/g dw for RCROP1, 24.55 ± 0.67 µmol TE/g dw for RCROP2) in the final product's formulation. Moreover, adding powder to cheese is an effective way to increase the value of onion by-products and produce polyphenol-enriched cheese.

Advanced interactional characterization of the inhibitory effect of anthocyanin extract from Hibiscus sabdariffa L. on apple polyphenol oxidase.

In this study, a comprehensive approach to advance the inhibitory effect of Hibiscus sabdariffa extract on apple polyphenol oxidase (PPO) was performed. PPO was extracted, purified, and characterized for optimal activity, whereas response surface methodology generated a quadratic polynomial model to fit the experimental results for hibiscus extraction. The optimum conditions allowed to predict a maximum recovery of anthocyanins (256.11 mg delphinidin-3-O-glucoside/g), with a validated value of 272.87 mg delphinidin-3-O-glucoside/g dry weight (DW). The chromatographic methods highlighted the presence of gallic acid (36,812.90 µg/g DW extract), myricetin (141,933.84 µg/g DW extract), caffeic acid (101,394.07 µg/g DW extract), sinapic acid (1157.46 µg/g DW extract), kaempferol (2136.76 µg/g DW extract), and delphinidin 3-O-ß-d-glucoside (226,367.08 µg/g DW extract). The inactivation of PPO followed a first-order kinetic model. A temperature-mediated flexible fit between PPO and anthocyanins was suggested, whereas the molecular docking tests indicated that PPO is a good receptor for cafestol, gallic acid, and catechin, involving hydrophobic and hydrogen bond interactions. PRACTICAL APPLICATION: It is well known that enzymatic browning is one of the most important challenges in the industrial minimal processing of selected fruit and vegetable products. Novel inhibitors for polyphenol oxidase are proposed in this study by using an anthocyanin-enriched extract from Hibiscus sabdariffa L. Based on our results, combining the chemical effect of phytochemicals from hibiscus extract with different functional groups with minimal heating could be an interesting approach for the development of a new strategy to inhibit apple polyphenol oxidase.

Technologically Driven Approaches for the Integrative Use of Wild Blackthorn (Prunus spinosa L.) Fruits in Foods and Nutraceuticals.

Different technological approaches were used in this study for the valorization of blackthorn (Prunus spinosa L.) fruits in marmalade, jam, jelly, and nutraceuticals. Marmalade showed the highest concentrations of polyphenols (7.61 ± 0.05 mg gallic acid equivalents/g dry weight (DW)) and flavonoids (4.93 ± 0.22 mg catechin equivalents/g DW), whereas jam retained the highest content of anthocyanins (66.87 ± 1.18 mg cyanidin-3-O-glucoside equivalents/g DW). A good correlation between polyphenol and flavonoid contents and antioxidant activity was found, the highest value being 21.29 ± 1.36 mmol Trolox/g DW for marmalade. Alternatively, the fresh pulp was enriched with inulin, followed by inoculation with Lactobacillus acidophilus, and freeze-dried, allowing a powder to be obtained with a viable cell content of 6.27 × 107 CFU/g DW. A chromatographic analysis of blackthorn skin revealed that myricetin (2.04 ± 0.04 mg/g DW) was the main flavonoid, followed by (+)-catechin (1.80 ± 0.08 mg/g DW), (-)-epicatechin (0.96 ± 0.02 mg/g DW), and vanillic acid (0.94 ± 0.09 mg/g DW). The representative anthocyanins were cyanidin 3-O-glucoside, cyanidin 3-O-rutinoside, and peonidin 3-O-glucoside, with an average concentration of 0.75 mg/g DW. The skin extract showed comparable IC50 values for tyrosinase (1.72 ± 0.12 mg/mL), α-amylase (1.17 ± 0.13 mg/mL), and α-glucosidase (1.25 ± 0.26 mg/mL). The possible use of kernels as calorific agents was demonstrated through the evaluation of calorific power of 4.9 kWh/kg.

Customized Technological Designs to Improve the Traditional Use of Rosa canina Fruits in Foods and Ingredients.

The rosehip fruits from Romanian spontaneous flora were valorized in three different customized variants, including jellified products, juices, and a nutraceutical. Prior to the technological design, the rosehip samples were characterized for individual polyphenolic content. The samples (non)-enzymatically treated showed epicatechin as the major compound, whereas the enzymatic treatment enhanced the extraction of quercetin (40.23 ± 0.48 mg/100 g DW extract), gallic acid (9.74 ± 0.24 mg/100 g DW extract), and kaempferol. Different ratios and types of sugars were added to obtain jellified products, leading to a significantly different bioactive profile. The sugar-free and steviol samples showed the highest content in carotenoids (89.36 ± 0.06 mg/g dry weight (DW) and 39.22 ± 1.16 mg/g DW, respectively), leading to the highest antioxidant activity (8.19 ± 0.80 mMol Trolox/g DW and 20.16 ± 0.31 mMol Trolox/g DW, respectively). The gelling capacity increased with the increase in sugar content. The enzymatically treated rosehip fruit pulp was mixed in various ratios with apple juice, followed by pasteurization. The polyphenolic content was approximately two times higher in the blended juices (20.75 ± 1.40 mg gallic acid equivalents (GAE)/100 mL). The overall impression highlighted the preferences of panelists for sugar-free products, whereas adding apple juice significantly influenced their preferences. The fresh pulp was enhanced with pectin, followed by inoculation with Lactobacillus acidophilus, and freeze-dried showed satisfactory cell viability (approximately 7 log CFU/g DW), whereas an antidiabetic, anti-tyrosinase and anti-obesity potential of the powder was suggested. Our results provide enough evidence for customized processing of rosehip fruits in foods and nutraceuticals as a response to consumers' choices, highlighting the bioactive compounds and nutrient contents, whereas selected in vitro health-related evidence was suggested.

Optimizing of the extraction conditions for anthocyanin's from purple corn flour (Zea mays L): Evidences on selected properties of optimized extract.

In this study, the Response Surface Methodology was used to optimize the extraction conditions for anthocyanins from purple corn flour (PCF), whereas the optimized extract was characterized in terms of phytochemicals content, inhibitory activity against metabolic associated enzymes and the potential to stimulate the metabolic activity of yeasts. The optimized conditions using a Box-Behnken design (BBD) of response surface methodology (RSM) were as follow: temperature (39 °C), extraction time (5 h), liquid/solid ratio (30 mL/g) and ethanol concentration (73 %), yielding a maximum response predicted and experimental values of 13.77 and 14.04 ± 0.02 mg cyanidin 3-O-glucoside equivalents (C3G)/g dry weight (DW). The extract showed a high content in myricetin, quercetin 3-ß-d-glucoside, kaempferol, whereas the main anthocyanin was C3G. The extract was test the effect on metabolic activity of Saccharomyces cerevisiae, with the highest multiplication rate obtained at 1.2 mg/100 mL. The extract showed potential antidiabetic, hypocholesterolemic and preventive effects against Parkinson's disease and melanoma. The findings provide the optimum conditions to obtain an anthocyanin enriched extract, for multiple applications.

Upgrading the Functional Potential of Apple Pomace in Value-Added Ingredients with Probiotics.

Emerging customized designs to upgrade the functional potential of freeze-dried apple pomace was used in this study, in order to transform the industrial by-products into ingredients containing probiotics, for a better and healthier food composition. The freeze-dried apple pomace was analyzed for free and bounded phenolic contents, highlighting a significant level of caffeic acid (4978.00 ± 900.00 mg/100 g dry matter (DM)), trans-cinnamic acid (2144.20 ± 37.60 mg/100 g DM) and quercetin 3-ß-D-glucoside (236.60 ± 3.12 mg/100 g DM). The pectin extraction yield was approximatively 24%, with a degree of esterification of 37.68 ± 1.74%, and a methoxyl content of 5.58 ± 0.88%. The freeze-dried apple pomace was added in a different ratio as a supplement to cultural medium of Loigolactobacillus bifermentans MIUG BL 16, suggesting a significant prebiotic effect (p < 0.05) at concentration between 1% and 2%. The apple pomace was used to design three freeze-dried ingredients containing probiotic, with a high level of polyphenolic content (6.38 ± 0.14 mg gallic acid equivalents/g DM) and antioxidant activity (42.25 ± 4.58 mMol Trolox/g DM) for the powder containing apple pomace ethanolic extract. When inulin was used as a prebiotic adjuvant, the obtained powder showed a 6 log/g DM viable cell count. The ingredients were added to fermented vegetable soy milk-based products, allowing us to improve the polyphenolic content, antioxidant activity and viable cell counts. The approach designed in this study allowed us to obtain ingredients suitable to add value to food, whereas premises to align with the current circular economy premises, by reintegrating the industrial waste as sources of high added value compounds, are also provided.

Extraction of Polyphenols and Valorization of Fibers from Istrian-Grown Pomegranate (Punica granatum L.).

Pomegranate fruit is an ancient fruit that is used not only because of its deep-red color and tasty arils but also due to the health benefits of its extracts. Pomegranate is a valuable source of bioactive compounds, including colorful anthocyanins and other polyphenols. The main objective of the present study was to gain comprehensive knowledge of the phenolic composition and antioxidative activity of a new pomegranate cultivar, grown in Northwest Istria, a part of the North Adriatic coastal area. Various parts of the pomegranate fruit parts were extracted in 70% ethanol or water. Total phenolic content and antioxidative capacity were respectively determined with Folin-Ciocalteu reagent and ABTS radical. Phenolics were examined and analyzed with TLC, LC-MS, and HPLC. Pomegranate juice was prepared from red arils and after thermal treatment, the stability of anthocyanins was monitored for several months to understand the effect of storage. The highest total phenolics were determined in ethanol pomegranate peel extracts (30.5 ± 0.6 mg GAE/g DM), and water peel extracts exhibited the highest antioxidative activity (128 ± 2 µg TE/g DM). After five months of storage of thermally treated pomegranate juice, 50-60 percentage points increase in anthocyanin degradation was observed. Pomegranate peel was further tested as a sustainable inedible food source for papermaking. Due to the low content of cellulose and the high percentage of extractives, as well as a distinguished texture and appearance, the paper made from pomegranate peel is best suited for the production of specialty papers, making it particularly interesting for bioactives recovery, followed by material restructuring.

Sustainable Design of Innovative Kiwi Byproducts-Based Ingredients Containing Probiotics.

Industrial processing of kiwifruits generates a large quantity of byproducts, estimated to be one million tons per year. The resulting byproducts are rich sources of bioactive components that may be used as additives, hence minimizing economic and environmental issues. In this study, kiwifruit byproducts were used to develop added-value food-grade ingredients containing probiotics. The byproducts were divided into peels and pomace. Both residues were inoculated with a selected strain of probiotic (Lacticaseibacillus casei 431®), and two variants were additionally enhanced with prebiotic sources (buckwheat and black rice flours). The inoculated powders were obtained by freeze-drying, and the final ingredients were coded as KP (freeze-dried kiwi peels), KBR (freeze-dried kiwi pomace and black rice flour), KPB (freeze-dried kiwi pomace and buckwheat flour), and KPO (freeze-dried kiwi pomace). The phytochemical profile was assessed using different spectrophotometric methods, such as the determination of polyphenols, flavonoids, and carotenoids. The kiwi byproduct-based formulations showed a polyphenolic content varying from 10.56 ± 0.30 mg AGE/g DW to 13.16 ± 0.33 mg AGE/g, and the survival rate of lactic acid bacteria after freeze-drying ranged from 73% to 88%. The results showed an increase in total flavonoid content from the oral to gastric environment and controlled release in the intestinal environment, whereas a maximum survival rate of probiotics at the intestinal end stage was 48%. The results of SEM and droplet size measurements revealed vesicular and polyhedral structures on curved surfaces linked by ridge sections. The CIEL*a*b* color data were strongly associated with the particular pigment in kiwi pulp, as well as the color of the additional flour. Finally, the ingredients were tested in protein bars and enhanced the value of the final food product regarding its phytochemical and probiotic content.

Chemical Composition and Antioxidant Profile of Sorghum (Sorghumbicolor (L.) Moench) and Pearl Millet (Pennisetumglaucum (L.) R.Br.) Grains Cultivated in the Far-North Region of Cameroon.

Sorghum and pearl millet are grain crops that can grow in semi-arid climates, with nutritional and bioactive properties superior to those of major cereals such as rice, wheat, and maize. However, these properties vary a lot, depending on the genetic factors, growing conditions, and place of cultivation. Four sorghum and two pearl millet grains cultivars grown in the Far-North region of Cameroon were screened for their chemical composition and antioxidant profile. The proximate and mineral analyses were performed using AOAC standard methods. The antioxidant profile was assayed spectrophotometrically and details on the phenolic compounds were investigated using HPLC. The pearl millet cultivars, especially mouri, showed higher contents of proteins, lipids, ash, calcium, copper, iron, and zinc. The red sorghum specifically exhibited the greatest amounts of total polyphenols (82.22 mg GAE/g DE), total flavonoids (23.82 mg CE/g DE), and total 3-deoxyanthocyanidin (9.06 mg/g DE). The most abundant phenolic compound was gallic acid, while the most frequent were chlorogenic and ferulic acids. The maximum antioxidant activity against DPPH was observed in yellow-pale sorghum (87.71%), followed by red sorghum (81.15%). Among the studied varieties of cereals, mouri pearl millet and red sorghum were the best sources of nutrients and bioactive compounds, respectively. Their consumption should be encouraged to tackle nutrient deficiencies and non-communicable diseases within local populations.

Thermal Stability and Inhibitory Action of Red Grape Skin Phytochemicals against Enzymes Associated with Metabolic Syndrome.

The present study focuses on heat-induced structural changes and the degradation kinetics of phytochemicals and antioxidant activity of red grape skin extract. The thermal degradation of anthocyanins, flavonoids, polyphenols, and antioxidant activity followed a first-order kinetic model, increasing with temperature due to the intensification of the degradation process. The activation energy (Ea) highlighted this phenomenon. Likewise, the kinetic and thermodynamic parameters certified the irreversible degradation of the bioactive compounds from the skin of the Babeasca neagra grape variety. Both temperature and duration of heating had a significant impact on the content of bioactive compounds. In addition, the red grape skin extract inhibited certain enzymes such as α-amylase, α-glucosidase, lipase, and lipoxygenase, which are associated with metabolic syndrome and inflammation. Further knowledge on the possible inhibition mechanisms exerted by the major anthocyanins found in red grape skin extract on the metabolic syndrome-associated enzymes was gathered upon running molecular docking tests. Detailed analysis of the resulting molecular models revealed that malvidin 3-O-glucoside binds in the vicinity of the catalytic site of α-amylase and lipase, whereas no direct contact with catalytic amino acids was identified in the case of α-glucosidase and lipoxygenase.

Supercritical CO2 Extraction and Microencapsulation of Lycopene-Enriched Oleoresins from Tomato Peels: Evidence on Antiproliferative and Cytocompatibility Activities.

Tomato peels are used as a valuable material to extract lycopene-rich oleoresins by supercritical CO2 extraction. The extraction involves continuous circling of CO2 to the extractor after removing the solute in the separators, S40 and S45, where the solvent power of the CO2 is reduced by reducing pressure down to 20 MPa in S40 and 5 MPa in S45, respectively, leading to two extracts. Lycopene is found to be the major compound, representing 93% and 76% of the total carotenoids in S40 and S45 extracts, respectively. The two extracts are microencapsulated in whey protein concentrate and acacia gum by complex coacervation and freeze-drying, leading to corresponding P40 and P45 powders, with antioxidant activity of 8.57 ± 0.74 and 9.37 ± 0.48 mMol TEAC/g DW in P40 and P45, respectively. Different structural and morphological patterns are observed, with finer microparticles of 1-2 µm in P45. Both powders show dose and time-dependent antiproliferative activity. The half-maximal inhibitory concentration values are 100 µg/mL for P40 and 750 µg/mL for P45 sample, indicating a higher antiproliferative effect of P40 over P45 in HT-29 cell culture. The powders have an extended range of cytocompatibility, up to 1000 µg/mL, in L929 normal cells, stimulating the cell growth. Lycopene retention is tested, and values of 48% and 29% in P40 and P45 are found after 21 days at 25 °C, with the degradation rate in P45 significantly higher, due to the higher content of the surface lycopene, which favored its degradation.

Bovine ß-lactoglobulin peptides as novel carriers for flavonoids extracted with supercritical fluids from yellow onion skins.

Our study describes in detail the binding mechanism between the main flavonoids that were extracted from onion skins by supercritical CO2 and peptides from whey proteins, from the perspective of obtaining multifunctional ingredients, with health-promoting benefits. The supercritical CO2 extract had 202.31 ± 11.56 mg quercetin equivalents/g DW as the major flavonoid and antioxidant activity of 404.93±1.39 mM Trolox/g DW. The experiments on thermolysin-derived peptides fluorescence quenching by flavonoids extract allowed estimating the binding parameters, in terms of binding constants, and the number of binding sites. The thermodynamic analysis indicated that the main forces involved in complex formation were hydrogen bonds and van der Waals interactions. Molecular docking tests indicated that peptide fluorescence quenching upon gradual addition of onion skin extract might be due to flavonoids binding by Val15 -Ser21 . All 7 to 14 amino acids long peptides appeared to have affinity toward quercetin-3,4'-O-diglucoside and quercetin-4'-O-monoglucoside. The study is important as a potential solution for reuse of valuable resources, underutilized, such as whey peptides and yellow onion skins flavonoids for efficient microencapsulation, as a holistic approach to deliver healthy and nutritious food. PRACTICAL APPLICATION: A growing interest was noticed in the last years in investigating the interactions between proteins and different biologically active compounds, such as to provide knowledge for efficient development of new food, pharmaceutical, and cosmetic products. Recent studies suggest that flavonoid-protein complexes may be designed to improve the functional performance of the flavonoids. The results obtained in this study bring certain benefits in terms of exploiting the bioactive potential of both flavonoids and bioactive peptides, for developing of formulas with improved functional properties.

Microencapsulation of Red Grape Juice by Freeze Drying and Application in Jelly Formulation.

The aim of this work is to obtain new food products enriched with bioactive compounds from concentrated grape juice microencapsulated by freeze drying using a whey protein isolate-chitosan system. The obtained powder showed an encapsulation efficiency of (86.1±4.0) %, with an anthocyanin mass fraction (expressed as cyanidin-3-O-glucoside equivalent) of (1.4±0.2) mg/g, while the total polyphenolic (expressed as gallic acid equivalents) and flavonoid (expressed as catechin equivalents) mass fractions were (3.3±0.6) and (1.6±0.5) mg/g, respectively. The confocal laser microscopy revealed the presence of the flavonoid pigments wrapped inside the matrix, whereas the anthocyanins were grouped into large and compact clusters. The microencapsulated powder was used for jelly formulation. The new food formulations have a satisfactory anthocyanin mass fraction ranging from (0.03±0.01) to (0.12±0.02) mg/g, while no significant differences were observed in flavonoid content. All the value-added jelly showed appreciable antioxidant activity. The in vitro digestibility results confirm a slow release of anthocyanins from the food matrices during simulated gastric digestion and a significant release of the bioactive compounds into the gut. The addition of microencapsulated powder caused a significant decrease in firmness, cohesiveness and springiness, leading to the destabilization of the gel structure, while reducing the attraction forces between the matrix components. The sensorial analysis indicated that the panellists preferred the sample with grape juice the most.

Fluorescence spectroscopy and molecular modeling of anthocyanins binding to bovine lactoferrin peptides.

This work was aimed to obtain lactoferrin peptides, with anthocyanins-binding capabilities, by using eggplant peels extract as a source of anthocyanins. The chromatographic analysis of the extract evidenced the presence of five individual anthocyanins, with delfinidin-3-rutinoside being identified as the predominant. 20 small peptides were identified, from which four are containing Trp at C-terminal. By estimating the thermodynamic parameters, van der Waals and hydrogen bonding were found to have important roles in binding of anthocyanins to LF and LF-derived peptides. In order to complement the experimental results, the in silico methods were further employed to add single molecule level details on the potential interactions between different peptides and the main anthocyanins from eggplant peels. The docking tests indicated that the Trp containing peptides can bind, with different affinities either delphynidine-3-glycoside or delphynidine-3-rutinoside, therefore explaining the fluorescence quenching results. Our results have indicated a mechanism for the interactions between anthocyanins and LF and its small molecular weight peptides, whereas providing insights for formulating ingredients and foods with enhanced bioactives-binding properties.

Valorizations of Sweet Cherries Skins Phytochemicals by Extraction, Microencapsulation and Development of Value-Added Food Products.

Sweet cherries are processed in various ways, leading to significant amounts of underutilized by-products that can potentially be used as a source of bioactive compounds, including antioxidants. The present study focuses on identifying ways to exploit bioactive compounds from sweet cherry skins, namely the extraction, microencapsulation, and functionalizing of some food product to obtain added value. The anthocyanins from skins were extracted and encapsulated in a combination of whey proteins isolate and chitosan by freeze-drying, with an encapsulation efficiency of 77.68 ± 2.57%. The powder showed a satisfactory content in polyphenols, of which anthocyanins content was 14.48 ± 1.17 mg cyanidin 3-glucoside/100 g dry weight (D.W.) and antioxidant activity of 85.37 ± 1.18 µM Trolox/100 g D.W. The powder was morphologically analyzed, revealing the presence of coacervates, ranging in size from 12-54 µm, forming large spheresomes (up to 200 µm). The powder was used as a functional ingredient to develop two value-added food products, namely yoghurt and marshmallows. The powder was tested for its prebiotic effect on L. casei 431® in the yoghurt samples during 21 days at 4 °C, when a decrease in viability was found, up to 6 log CFU·g-1. The anthocyanins and antioxidant activity decreased in yoghurt and increased in marshmallows during storage time. The obtained results support the potential use of extracts from underutilized sources in the development of functional ingredients and value-added food products.

Antioxidative Capacity of and Contaminant Concentrations in Processed Plum Products Consumed in Romania.

The bioactive compounds (total phenols, anthocyanins, and flavonoids) and antioxidant activity of plum-based products (prunes, jams, and marmalade) were evaluated based on spectrophotometric assays and acrylamide and 5-hydroxymethyl-2-furaldehyde concentrations to determine the quality and safety of these products in the Romanian marketplace. The total polyphenol concentrations in prunes, marmalade, and jams were 0.93 to 5.63 g of gallic acid equivalent per kg of dry matter, and the antioxidant activity was 3.0 to 17.2 mmol/kg. The concentrations of potentially harmful acrylamide in the plum products ranged from the limit of quantitation (<20 µg/kg) to 37.44 µg/kg, and the concentration was higher in prunes (26.66 to 163.72 µg/kg) than in jams. The 5-hydroxymethyl-2-furaldehyde concentrations in plum products were also variable, at 36 to 2,149 mg/kg. These data revealed a very low concentration of acrylamide in thermally processed plum products, and the results for total polyphenols and the antioxidant activity of prunes and plum jams may be relevant for evaluating these products as important sources of bioactive compounds.

The kinetics of thermal degradation of polyphenolic compounds from elderberry ( Sambucus nigra L.) extract.

This main focus of this study was to evaluate the thermal degradation kinetics and the phytochemical characterization of the elderberries extract. Pelargonidin-3-sophoroside and delphinidin-3-glucoside were identified as the major anthocyanin compounds and catechin hydrate as the major flavonoid compound. In order to further understand the action of the heat treatment on the bioactive compounds from elderberry extract, fluorescence studies were also carried out. In general, heating at temperatures ranging from 100 to 150 ℃ for up to 90 min caused a decrease in fluorescence intensity, simultaneously with significant redshifts in λmax suggesting important molecular changes inside the anthocyanins structure, affecting the antioxidant activity. Increasing the heating time up to 120 min, the elderberry extract peaked at about 88 nm shifted toward higher wavelengths with respect to that of untreated solutions (peak at 442 nm). The kinetics studies of anthocyanins, fluorescence intensity, and antioxidant activity evidenced a decrease of the degradation rate constants with increased temperature while the activation energies for heat-induced fluorescence intensity, monomeric anthocyanins, and antioxidant activity were 39.62 ± 9.60, 49.97 ± 5.61, and 31.04 ± 19.92 kJ/mol, respectively. Our results can be valuable in terms of establishing the appropriate processing and formulation protocols that could lead to a more efficient utilization of these pigments in actual food products and/or nutraceuticals.

Phytochemicals content and antioxidant properties of sea buckthorn (Hippophae rhamnoides L.) as affected by heat treatment - Quantitative spectroscopic and kinetic approaches.

The effect of thermal processing (50-100°C) on the degradation of the phytochemicals in sea buckthorn extract was investigated using chromatographic, fluorescence and FT-IR spectroscopy techniques and degradation kinetics. Heating the sea buckthorn extract resulted in structural changes that led to red- or blue-shifts in maximum emission, depending on temperature and excitation wavelengths. The attenuated total reflectance analysis of the sea buckthorn extract revealed a satisfactory thermostability of compounds at high temperatures. A fractional conversion kinetic model was used to describe the mechanism of degradation in terms of rate and activation energy. Activation energies for total carotenoids, polyphenolic, flavonoids, and antioxidant activity were 8.45±0.93kJ/mol, 2.50±0.66kJ/mol, 22.50±7.26kJ/mol and 15.22±2.75kJ/mol, respectively. The kinetic parameters evidence a higher thermal stability of carotenoids and polyphenols, suggesting higher degradation rates for flavonoids and antioxidant activity. Our results demonstrate that industrial process optimization in terms of time-temperature combinations demands product specific kinetic data.

Thermal and high-pressure inactivation kinetics of polyphenol oxidase in Victoria grape must.

The inactivation kinetics of polyphenol oxidase (PPO) in freshly prepared grape must under high hydrostatic pressure (100-800 MPa) combined with moderate temperature (20-70 degrees C) was investigated. Atmospheric pressure conditions in a temperature range of 55-70 degrees C were also tested. Isothermal inactivation of PPO in grape must could be described by a biphasic model. The values of activation energy and activation volume of stable fraction were estimated as 53.34 kJ mol(-1) and -18.15 cm3 mol(-1) at a reference pressure of 600 MPa and reference temperature of 50 degrees C, respectively. Pressure and temperature were found to act synergistically, except in the high-temperature-low-pressure region where an antagonistic effect was found. A third-degree polynomial model was successfully applied to describe the temperature/pressure dependence of the inactivation rate constants of the stable PPO fraction in grape must.