No abstract

In this study, Cabernet Sauvignon red wine was subjected to reverse osmosis and nanofiltration processes at four different pressures (25, 35, 45, and 55 bar) and two temperature regimes (with and without cooling). The aim was to obtain concentrates with a higher content of phenolic compounds and antioxidant activity and to determine the influence of two membrane types (Alfa Laval RO98pHt M20 for reverse osmosis and NF M20 for nanofiltration) and different operating conditions on phenolics retention. Total polyphenol, flavonoid, monomeric anthocyanin contents, and antioxidant activity were determined spectrophotometrically. Flavan-3-ols and phenolic acids were analyzed on a high-performance liquid chromatography system and sample colour was measured by chromometer. The results showed that the increase in applied pressure and decrease in retentate temperature were favorable for higher phenolics retention. Retention of individual compounds depended on their chemical structure, membrane properties, membrane fouling, and operating conditions. Both types of membranes proved to be suitable for Cabernet Sauvignon red wine concentration. In all retentates, phenolic compounds content was higher than in the initial wine, but no visible color change (ΔE* < 1) was observed. The highest concentrations of phenolic compounds were detected in retentates obtained at 45 and 55 bar, especially with cooling.

Wine aroma represents one of the main properties that determines the consumer acceptance of the wine. It is different for each wine variety and depends on a large number of various chemical compounds. The aim of this study was to prepare red wine concentrates with enriched aroma compounds and chemical composition. For that purpose, Cabernet Sauvignon red wine variety was concentrated by reverse osmosis (RO) and nanofiltration (NF) processes under different operating conditions. Different pressures (2.5, 3.5, 4.5 and 5.5 MPa) and temperature regimes (with and without cooling) were applied on Alfa Laval LabUnit M20 equipped with six composite polyamide RO98pHt M20 or NF M20 membranes. Higher pressure increased the retention of sugars, SO2, total and volatile acids and ethanol, but the temperature increment had opposite effect. Both membranes were permeable for water, ethanol, acetic acid, 4-ethylphenol and 4-ethylguaiacol and their concentration decreased after wine filtration. RO98pHt membranes retained higher concentrations of total aroma compounds than NF membranes, but both processes, reverse osmosis and nanofiltration, resulted in retentates with different aroma profiles comparing to the initial wine. The retention of individual compounds depended on several factors (chemical structure, stability, polarity, applied processing parameters, etc.).

Summary The aim of this study was to investigate influence of partial replacement of sucrose with trehalose on phenolics, antioxidant activity, colour and texture of orange jelly during 135 days of storage under the light at room temperature. After preparation, phenol content was 1185.6 and 1050.3 mg GAE kg−1 in orange jelly and orange jelly with trehalose addition, respectively. Loss of phenols during 135 days of storage in orange jelly was 27.8% in comparison with 9.14% in orange jelly with trehalose addition. Browning index of samples with trehalose addition had lower values than orange jelly after their preparation as well as after storage. Evaluated textural parameters were gel strength, rapture strength, brittleness and adhesiveness. After preparation, both jellies had the same gel strength and adhesiveness. Orange jelly had higher rapture strength and higher value of brittleness than orange jelly with trehalose addition.

It is well known that carbohydrates are the main source of calories in most diets. However, by inhibiting carbohydrases, intake of calories is reduced and weight loss is improved. α-amylase is an enzyme that hydrolyses α-1,4 glycosidic linkages of α-linked polysaccharides, resulting in low-molecular-weight products such as glucose, maltose and maltotriose, while α-glucosidase catalyzes the hydrolysis of nonreducing α-1,4-linked glucose moieties from disaccharides or oligosaccharides. Currently, one of the most common nutritional disorders in the world is hyperglycemia. One of the new therapeutic approaches to treat this disease is the application of natural inhibitors, such as polyphenols, that control starch digestion and regulate blood glucose level. Dietary polyphenols showed potential inhibitory activity against α-amylase and α-glucosidase and this review summarizes the recently published literature that studied inhibition mechanisms and the structure–activity relationship between individual dietary polyphenols and mentioned digestive enzymes. It is known that higher binding interactions cause higher inhibitory activities; thus, different polyphenols can affect different steps in the digestion of polysaccharides. The aim of this review is to clarify these mechanisms and to introduce polyphenol-rich functional foods as potential tools for the inhibition of α-amylase and α-glucosidase.