Infusion of grape phenolics into fruits and vegetables by osmotic treatment: Phenolic stability during air drying

Neuroprotective Potential of Thinned Peaches Extracts Obtained by Pressurized Liquid Extraction after Different Drying Processes

Genetic, environmental and nutritional factors are suggested as primary factors of Alzheimer’s disease (AD), and secondary metabolites such as polyphenols present in thinned peaches are considered as good candidates for AD prevention. Thinned peaches are usually dried to avoid putrefaction, but the effects of the drying method and the extraction process on the polyphenol composition and the neuroprotective potential have never been addressed. In this work, a pressurized liquid extraction (PLE) method was optimized and applied to thinned peaches dried under different conditions, and their neuroprotective potential was evaluated in vitro. In addition, the PLE extracts were characterized via HPLC-Q-TOF-MS/MS, and a permeability assay was performed to evaluate the ability of the identified metabolites to cross the blood–brain barrier (BBB). The PLE extracts obtained from freeze-dried (FD) samples with 50% ethanol in water at 180 °C showed the best neuroprotective potential. Finally, among the 81 metabolites identified, isoferulic acid, 4-methyldaphnetin, coniferyl aldehyde and 3,4-dihydroxyacetophenone were found at higher concentrations in FD extracts. These metabolites are able to cross the BBB and are positively correlated with the neuroprotective potential, suggesting FD together with PLE extraction as the best combination to exploit the neuroprotective capacity of thinned peaches.

Changes in Phytochemical Profiles and Biological Activity of Olive Leaves Treated by Two Drying Methods

Olive leaves, which are the most abundant byproducts of the olive industry, offer multiple health benefits. The investigation of the phytochemical profiles and relevant biological activities is an essential step toward transforming these low-value byproducts into value-added ones. This study systematically investigated the phytochemical profiles, antioxidant capacity, and inhibition rates of olive leaves from four cultivars on the α-glucosidase, α-amylase, and angiotensin-converting enzyme (ACE). The leaves were prepared using two common drying methods, namely, hot air-drying and freeze-drying. A total of 33 bioactive compounds were identified in the olive leaves, namely, 19 flavonoids, 2 phenylethanoids, 2 coumarins, 2 hydroxycinnamic acids, 2 iridoids, and 6 triterpenic acids. Quantification of the bioactive compounds revealed high amounts of polyphenols, especially flavonoids [2,027–8,055 mg/kg dry weight (DW)], iridoids (566–22,096 mg/kg DW), and triterpenic acids (13,824–19,056 mg/kg DW) in the olive leaves. The hot air-dried leaves showed significantly (P < 0.05) higher iridoid (oleuropein and secoxyloganin) content than the fresh leaves, while freeze-drying resulted in significantly (P < 0.05) higher flavonoid aglycone and hydroxytyrosol content. Additionally, freeze-drying led to samples with the highest radical scavenging, α-amylase, α-glucosidase, and ACE inhibition abilities. The flavonoid (e.g., quercetin, luteolin, eriodictyol, kaempferol-7-O-glucoside, and luteolin-7-O-glucoside), hydroxytyrosol, and oleanolic acid contents in the olive leaves were positively correlated (P < 0.05) with their bioactive potentials.

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.

Immunomodulation effects of polyphenols from thinned peach treated by different drying methods on RAW264.7 cells through the NF-κB and Nrf2 pathways

Thinned peach is abundant in polyphenols, and has been shown to exhibit various bioactivities. In this study, we evaluated the underlying immunomodulatory activity of polyphenol extracts of thinned peach (PETP) via the NF-κB and Nrf2 signaling pathways in RAW264.7 macrophages. The results demonstrated that the PETP efficiently activated the nuclear translocation of NF-κB and Nrf2, as well as downstream cytokines (IL-1β, IL-6, TNF-α and IFN-γ), SOD activity and ROS levels in RAW264.7 cells. Specifically, the PETP of natural drying and hot air drying exhibited less efficacy than that of freeze drying in NF-κB pathway. Interestingly, the PETP of hot air drying at 50 °C was more effective than freeze-dried PETP in activating Nrf2 nuclear translocation. Additionally, 50 µg/mL PETP enhanced immune responses, whereas 800 µg/mL PETP inhibited inflammatory development in macrophages. These findings indicated that different PETP affected the immunomodulation effects differently, which associated with the drying methods and incubation concentrations.

Effect of ultrasonic vacuum pretreatment on mass transfer kinetics during osmotic dehydration of black jamun fruit

The study investigates the effects of novel combination of ultrasound and vacuum pre-treatment on osmotic dehydration of black jamun fruit. The osmotic dehydration was conducted under three different conditions namely atmospheric osmotic dehydration (AOD), vacuum pre-treated osmotic dehydration (VOD), ultrasonic vacuum pre-treated osmotic dehydration (USVOD). The changes in water and solute content during osmotic dehydration were fitted to Peleg model to predict the equilibrium moisture and solute content values. The adequacy of Weibull distribution model for predicting the moisture and solute contents during osmotic dehydration at different temperatures were assessed. The effective diffusivity of samples in AOD, VOD and USVOD were estimated by application of Fick's second law. The high regression coefficient (R² > 0.9) and low χ² value represented the suitability of Peleg model for predicting equilibrium moisture and solute content and Weibull model for predicting both moisture and solute fraction in jamum fruit during AOD, VOD and USVOD processes. Both vacuum and ultrasound vacuum pretreatment enhanced the moisture loss and solute uptake during osmotic dehydration. The results showed the osmotic drying rate was significantly influenced by different pre-treatment techniques and both vacuum and ultrasonic vacuum pretreatment process enhanced moisture loss and solute uptake during osmotic dehydration. The effective moisture and solute diffusivity were highest in ultrasonic vacuum pretreated samples and the values at 30-50 °C temperature were ranged from 8.53 × 10^-10 to 9.27 × 10^-10 m²/s and 3.81 × 10^-10 to 4.39 × 10^-10 m²/s respectively. The results were interrelated to changes in tissue structure caused by application of vacuum and ultrasonic vacuum pretreatment.

Evaluation and modelling of osmotic pre-treatment of peach using alternative agents in a multiple-component solution

BACKGROUND

Peach is a perishable fruit of great importance for the Greek food export market which is prone to rapid deterioration after harvesting. Its short shelf life can be substantially prolonged by applying an appropriate osmotic dehydration (OD) pre-treatment, which is a mild, non-thermal procedure. The aim of this study was to describe mass transfer and quality retention induced by the OD process.

RESULTS

Peach pieces were immersed in tertiary solutions of glycerol, erythritol, steviol glucosides and mineral salts at pre-selected OD conditions (25-45 °C for 3-240 min, w_fruit /w_solution = 1:5). Water loss (WL), solid gain (SG), water activity (a_w ) as well as representative quality indices (colour, texture) were measured during OD, showing that osmotically dehydrated peach presented significant a_w reduction (from 0.97 to 0.88) combined with quality retention.

CONCLUSION

This research showed that OD can be an effective pre-processing step in the production of intermediate moisture novel products. A second-degree polynomial model was developed describing adequately the effect of OD time and temperature and glycerol concentration on WL, SG, a_w , colour and texture of osmotically dehydrated peach, and analysis of variance was applied to identify those factors that significantly affect the aforementioned parameters. It was concluded that OD using alternative osmotic agents is an efficient method with respect to product colour and texture retention, allowing for the production of novel products with extended shelf life. © 2018 Society of Chemical Industry.

Influence of storage conditions in the evolution of phytochemicals in nutraceutical products applying high resolution mass spectrometry

An adequate knowledge about possible transformation of bioactive compounds in nutraceutical products during long storage is important in order to know potential modifications of this type of compounds. In this study, one year monitoring was performed in different types of nutraceutical products based on natural extracts (green tea, soy, royal jelly and grapes) observing the appearance of new bioactive compounds, which were not detected at the initial conditions, as well as the decrease of some of the detected compounds. To determine these transformation products, an analytical procedure based on high resolution mass spectrometry (Exactive-Orbitrap analyzer) was applied. It was noted that transformation products were detected after 3 months of storage in green tea and soy products, while 6 months were necessary to observe transformation products in royal jelly.

Effect of osmotic treatments and drying methods on bioactive compounds in papaya and tomato

FIR and hot air drying enhanced lycopene and lutein contents, whereas osmotic treatment preserved sinapic acid and ferulic acid.

Use of dehydrated waste grape skins as a natural additive for producing rosé wines: study of extraction conditions and evolution

Dehydrated waste grape skins from the juice industry were used as an additive to produce rosé wines. Maceration time, particle size, dosage, alcoholic content, and maceration temperature were first studied in model wine solutions using two different dehydrated waste grape skins. Full factorial experimental designs together with Factor Analysis and Multifactor ANOVA allowed for the evaluation of each parameter according to the composition of color and phenolic and aroma compounds. Higher maceration time favored the extraction of anthocyanins; phenolic compound release was influenced by dosage independent from other factors studied. Rosé wines were produced by direct addition of dehydrated waste grape skins, according to selected parameters in two different white wines, achieving characteristics equivalent to commercial rosé wines. After three months of storage, rosé wine composition was stable.