Application of High-Pressure Homogenization for Apple Juice: An Assessment of Quality Attributes and Polyphenol Bioaccessibility.

In the current work, the influence of high-pressure homogenization (HPH) (200, 250, and 300 MPa) on pH, Brix, turbidity, viscosity, particle size distribution (PSD), zeta potential, color, polyphenol oxidase (PPO), peroxidase (POD), polyphenol profile and bioaccessibility of total phenolic compounds was studied. The results show no change in the apple juice's pH, TSS and density. In contrast, other physiochemical properties of apple juice treated with HPH were significantly changed. Besides total phenolic content (15% degradation) in the HPH-treated apple juice at 300 MPa, the PPO and POD activities were reduced by a maximum of 70 and 35%, respectively. Furthermore, among different digestion stages, various values corresponding to PSD and zeta potential were recorded; the total phenolic content was gradually reduced from the mouth to the intestine stage. The polyphenol bioaccessibility of HPH-treated apple juice was 17% higher compared to the untreated apple juice.

Bioaccessibility of Betalains in Beetroot (Beta vulgaris L.) Juice under Different High-Pressure Techniques.

The influence of high hydrostatic pressure (HHP) and supercritical carbon dioxide (SCCD) on the bioaccessibility of betalains in beetroot (Beta vulgaris L.) juice was investigated. Freshly squeezed juice (FJ) was treated at a mild temperature of 45 °C for 10 min (T45), pasteurization at 85 °C for 10 min (T85), HHP at 200, 400, and 500 MPa at 20 °C for 5 min (HHP200, HHP400, HHP500) and SCCD at 10, 30 and 60 MPa at 45 °C for 10 min (SCCD10, SCCD30, SCCD60). The juice was subjected to an in vitro digestion system equipped with dialysis. The content of betalains was measured with the aid of a High-Performance Liquid Chromatography (HPLC), the antioxidant capacity (AC) (ABTS•+, DPPH•) was analyzed during each digestion step, and the bioaccessibility of betacyanins and betaxanthins was assessed. The SCCD at 30 and 60 MPa significantly increased pigments' bioaccessibility compared with other samples. The 30 MPa proved particularly advantageous, as it increased the bioaccessibility of the total betacyanins and the betaxanthins by 58% and 64%, respectively, compared to the T85 samples. Additionally, higher bioaccessibility of betacyanins was noted in HHP200 and HHP400, by 35% and 32%, respectively, compared to FJ, T45, and T85 samples. AC measured by ABTS•+ and DPPH• assays were not unequivocal. However, both assays showed significantly higher AC in SCCD60 compared to T85 (21% and 31%, respectively). This research contributed to the extended use of the HHP and/or SCCD to design food with higher health-promoting potentials.

Bioaccessibility of Antioxidants in Blackcurrant Juice after Treatment Using Supercritical Carbon Dioxide.

Blackcurrant juice (Ribes nigrum L.) was subjected to supercritical carbon dioxide (SCCD) at 10, 30, and 60 MPa for 10 min at 45 °C, as well as thermally treated at 45 and 85 °C for 10 min to determine the stability, antioxidant capacity (AC), and bioaccessibility (BAc) of vitamin C, total anthocyanins, and their individual monomers. An in vitro gastrointestinal digestion model completed with dialysis was used to assess BAc. The use of SCCD at each of the pressures applied improved the stability of vitamin C, total anthocyanins, and AC before in vitro digestion. As a result of digestion, the total content of vitamin C, anthocyanins, and AC decreased. The highest BAc of vitamin C was noted in fresh juice (FJ) (40%) and after mild heat treatment at 45 °C (T45) (46%). The highest BAc of total anthocyanins was also noted in the FJ (4.4%). The positive effect of the application of SCCD on the BAc of the delphinidin-3-O-glycosides was observed compared to T45 and thermal pasteurization at 85 °C (T85). Although SCCD did not significantly improve the BAc of vitamin C and total anthocyanins, the higher AC of SCCD samples after intestinal digestion (ABTS+• and DPPH•) and in dialysate (ABTS+•) compared to thermally treated was observed. The protocatechuic acid was detected by UPLC-PDA-MS/MS as the major metabolite formed during the digestion of delphinidin-3-O-rutinoside. This may indicate the influence of SCCD on improvement of the accessibility of antioxidants for digestion, thanks to which more metabolites with high antioxidant activity were released.

The Bioaccessibility of Antioxidants in Black Currant Puree after High Hydrostatic Pressure Treatment.

The aim of the study was to investigate the effect of high-pressure processing (HPP) and thermal processing (TP) on the bioaccessibility of vitamin C and anthocyanins as well as changes in the antioxidant capacity (AC) using ABTS+• and DPPH• tests on blackcurrant (Ribes nigrum L.) puree during the steps in the digestive process. The puree was subjected to HPP at 200, 400, and 600 MPa for 5 min (room temperature) or TP at 85 °C for 10 min. The controls were untreated puree (P) and fruit crushed in a mortar (M). All the samples were digested in a static in vitro digestion model, including the mouth, stomach, and small intestine, and subjected to dialysis. The vitamin C, anthocyanin, and antioxidant capacity were monitored at each step of the digestion process. The potential bioaccessibility of the antioxidants studied was calculated in relation to the undigested sample. TP and HPP enabled a high content of vitamin C, anthocyanins, and AC to be maintained. After simulated digestion in the small intestine, a significant decrease was observed in the vitamin C and anthocyanins (approximately 98%) content. However, a high stability (approximately 70%) of both compounds was noted at the gastric stage. HPP and TP significantly affected the potential bioaccessibility of vitamin C and anthocyanins, although the bioaccessibility of both compounds in the samples treated using HPP was higher than when using TP. Moreover, the potential bioaccessibility of vitamin C after HPP treatment (400 and 600 MPa) was higher than the bioaccessibility calculated for the M and P control samples. TP and HPP treatment negatively affected anthocyanin bioaccessibility after dialysis. The most favorable pressure was 400 MPa, as it allowed maintaining the best antioxidant activity after digestion.