Stability of Bioactive Compounds and Antioxidant Activity in Rosehip Juice (Rosa spp.)

Rosehip fruits, characterized by their high concentrations of bioactive compounds and antioxidant activity (AA), have been traditionally used to make jams, infusions, and juices. Thus, the objective of this research was to evaluate the stability of rosehip juice by determining the concentrations of bioactive compounds and total phenols and the AA using chromatographic and spectroscopic methods. The stability of the juice was evaluated with three treatments and different storage conditions, namely, unpasteurized-refrigerated, pasteurized-room temperature, and pasteurized-refrigerated, and measurements were taken for eight months. Individual and total phenolic compounds, evaluated by chromatographic methods, reported differences until the end of this study. The total phenolic compounds by Folin-Ciocalteu method presented an average decrease of 57% in the three treatments in relation to the initial conditions. On the other hand, the ascorbic acid content decreased considerably, disappearing at week six. Furthermore, for the unpasteurized-refrigerated and pasteurized-refrigerated samples, a correlation was found between flavonols, total phenols, ascorbic acid, and antioxidant activity determined by the TEAC method. For the pasteurized-room temperature samples, correlations were found between the levels of several flavonols, hydroxycinnamic acid, total phenols, and ascorbic acid and the antioxidant activity determined by the CUPRAC method. The stability of the compounds was mainly correlated with the storage conditions of the juice and not with pasteurization. The highest stability was observed for the unpasteurized-refrigerated and pasteurized-refrigerated samples. Although the concentrations of the compounds evaluated decreased during this study, significant levels of AA persisted, providing beneficial characteristics for consumer health.

Phenolic composition, antioxidant capacity and physical characterization of ten blackcurrant (Ribes nigrum) cultivars, their juices, and the inhibition of type 2 diabetes and inflammation biochemical markers

The objective was to analyze the phenolic composition, antioxidant capacity, and physical characteristics of 10 blackcurrant cultivars, their juices, and the enzymatic inhibition of dipeptidyl peptidase-IV, α-amylase, α-glucosidase, nitric oxide synthase, and cyclooxygenase-2. Fruit masses ranged from 0.47 to 1.22 g and diameters from 7.42 to 14.42 mm. For the juices, pH ranged from 2.80 to 2.96, soluble solids from 11.33% to 17.5%, total acidity from 3.17 to 4.26 g/100 mL, and viscosity from 1.28 to 273.83 mPa·s. Total anthocyanins (TA) ranged from 1.81 to 5.48 mg eq cyanidin 3-O-glucoside/100 g, total polyphenols (TP) from 7.67 to 39.70 mg eq gallic acid/100 g, total condensed tannins from 3.24 to 7.76 g eq catechin/100 g, and antioxidant capacity from 219.24 to 499.26 μmol eq Trolox/100 g. Juices of the cultivars Coronet and Consort contained the highest levels of TA, TP, and antioxidants. Whistler cultivar contained high concentrations of major anthocyanins. Juices from all cultivars favorably inhibited the activities of enzymes used as surrogate biochemical markers for T2 diabetes and inflammation.

Storage Stability of Novel Functional Drinks Based on Ricotta Cheese Whey and Fruit Juices

To study the storage stability of drinks produced by blending ricotta cheese whey (RCW) with fruit juices, apple-RCW and apple and blueberry mix (50:50)-RCW (juice/RCW ratio: 70/30, 14.5% soluble solids content) were prepared. Color, sugar and organic acid profiles, antioxidant composition, and sensory features were analyzed after 15 to 150 days of storage on an open shelf at room temperature. A browning phenomenon occurred in the apple-RCW-based drink, while no significant color changes occurred in the mix-based drink. Significant degradation of polyphenol compounds (TPC) occurred in both drinks, but more markedly in the mix-based one. Storage strongly influenced the stability of the total monomeric anthocyanins (MAP) due to their sensitivity to temperature and light. Antioxidant capacity was preserved in both drinks, suggesting that the antioxidant capacity of Maillard reaction products and/or polymeric anthocyanins formed during storage compensated for the TPC/MAP loss. Sugar and organic acid profiles changed without influencing the sensory characteristics. Except for the sourness intensity in the apple-based drink, which increased significantly, storage did not negatively influence the sensory parameters, so both RCW-based drinks obtained high acceptance scores at the end of the storage period. Despite the bioactive compound losses, both drinks provided interesting nutritional value at the end of the storage period, particularly the mix-based drink. The overall results showed that both products are stable enough to hypothesize their commercialization.