Cabernet Sauvignon Red Must Processing by UHPH to Produce Wine Without SO2: the Colloidal Structure, Microbial and Oxidation Control, Colour Protection and Sensory Quality of the Wine

Abstract

A cryo-macerated must of V. vinifera L. cabernet sauvignon was processed by ultra-high-pressure homogenisation (UHPH) sterilisation without the use of SO2. The UHPH treatment of the must was carried out continuously at a pressure of 300 MPa and reaching a maximum temperature of 77 °C for less than 0.2 s. The colloidal structure of the UHPH must was evaluated by atomic force microscopy (AFM) measuring an average particle size of 457 nm. The initial microbial load was 4-log CFU/mL (yeast), 3-log CFU/mL (bacteria). No yeast and non-sporulating bacteria were detected in 1 mL and 10 mL of the UHPH-treated must, respectively. Furthermore, no fermentative activity was detected in the non-inoculated UHPH-treated musts for more than 50 days. A strong inactivation of the oxidative enzymes was observed, with lower oxidation (≈ × 3) than controls. The antioxidant activity of the UHPH-treated must was much higher (106%) than that of the control must. UHPH had a protective effect in total anthocyanins, and especially in acylated anthocyanins (+ 9.3%); furthermore, the fermentation produces fewer higher alcohol (-44,3%) and more 2-phenylethyl acetate (+ 63%).

Red Wine and Health: Approaches to Improve the Phenolic Content During Winemaking

“…UHPH is a continuous flow technique applicable to liquid samples, for example, musts, at pressures between 200 and 600 MPa, followed by instantaneous depressurization to atmospheric pressure with the consequent generation of 100–300 nm nanofragmentations in the treated sample ( 94 ). It is characterized by having a total process time of 0.2 s, with the advantage of not generating damage at the level of vitamins, aromatic compounds, and pigments, even at temperatures close to 80 ° C ( 94 , 107 , 110 ). Another advantage of UHPH is a greater release of nitrogenous compounds for the nutrition of the yeast in the treated musts, besides allowing the synthesis of fermentative esters with a positive impact on the aroma of the wine compared to the conventional treatment with SO 2 ( 109 ).…”

“…However, one of the challenges to overcome with this technology is its applicability in red musts containing peels and seeds (grape mash), considering that this technology has been evaluated in liquid foods with particle sizes of less than 0.5 mm ( 94 ). An alternative to taking advantage of the benefits of UHPH would be its sequential application in processes that include maceration in the presence of peels and seeds, with subsequent draining, for the later application of UHPH to the pure must, according to the methodology proposed by Vaquero et al ( 110 ). It could also include the application of US, PEF, irradiation, or ozone in the maceration stage, with subsequent draining of the must and application of UHPH to reduce the microbial load and inactivate PPO, protecting polyphenols against oxidation.…”

“…The application of UHPH allows an almost complete inactivation of the enzyme polyphenoloxidase (PPO) (> 90%) ( 107 , 109 ), with the consequent protection of phenolic compounds, besides maintaining the antioxidant capacity of the must, and color stability, even when exposed to air ( Table 2 ) ( 110 ), being greater its capacity to inactivate oxidative enzymes concerning high hydrostatic pressure (HHP).…”

“…Considering that one of the main advantages of UHPH is its inhibitory effect on PPO ( 107 , 109 , 110 ), an interesting alternative has recently been reported in Cabernet Sauvignon red must ( 110 ), which, after a maceration process at 0 ° C for 15 days, was separated from peels and seeds, and subsequently treated with UHPH at 300 MPa ( Table 2 ). Among the most important results, the maintenance of anthocyanin levels in the wine produced stands out.…”

“…Another alternative could include the application of technologies that allow greater extraction of phenolic compounds during maceration from the grape mash, such as ultrasound, pulsed electric fields, irradiation, or ozone, following the methodology developed by Vaquero et al ( 110 ), with the subsequent draining of the must to separate seeds and peels, followed by the application of UHPH to reduce the microbial load and inactivate the PPO, protecting the polyphenols against oxidation.…”