Effects of high hydrostatic pressure in preventing enzimatic browning and fermentation of fresh cut vacuum-packaged peaches

DENOYA GABRIELA; GABILONDO JULIETA; BUDDE CLAUDIO; GUIDI SILVINA; NANNI MARIANA; SANOW CLAUDIO; VAUDAGNA SERGIO R.; POLENTA BUSTAVO

Skukuza

Congreso; 2nd All Africa Horticulture Congress “Horticulture for Humanity”; 2012

SASHS

Consumers demand fresh cut fruits, free from additives and with fresh appearance. However, the alteration caused to the tissues by the processing operations such as peeling and cutting causes an increase in the metabolic activity and microbial spoilage, which limits the shelf life of these products. One of the major alteration problems of fresh cut fruits is the enzymatic browning, which is catalyzed by the enzyme Poliphenoloxidase (PPO). In the last years, high Hydrostatic Pressure (HHP) has been proposed as a less aggressive alternative to conventional thermal treatments for preservation. This technology could preserve products without altering covalent bonds, so nutritional- and sensorial-associated compounds with low molecular weight are not affected. However, the well-known baroresistance of PPO in some matrices hampers the successful application of HPP. One drawback associated with HHP application is that products must be vacuum packaged before pressurized, which could induce fermentation in living tissues; however, some evidences indicate that the application of HPP before the storage of vacuum-packed products can prevent this problem. The aim of this work is to study the effect of HHP in preventing enzymatic browning and induction of fermentation in vacuum-packaged fresh cut peaches. Cubes of Prunus Persicae cv. limon marelli were washed, dipped first in HClO 200ppm solution for superficial decontamination, and then in a solution of 1% ascorbic acid and 1% citric acid for the inhibition of enzymatic browning. Afterwards, cubes were packaged in Cryovac BB4L film and submitted to three treatments: A) samples were vacuum-packaged and treated with HHP (500MPa-5 min) with a Stanted Fluid Power Ltd. High Pressure Iso-Lab System; B) samples were vacuum-packaged without HHP application and C) samples were neither pressurized nor vacuum packaged. To evaluate the prevention of enzymatic browning, PPO activity was assessed in fruit extracts, while to evaluate fermentation of the product, ethanol production was measured during refrigerated storage (4ºC). Determinations were carried out at days 0, 15 and 21. Samples treated with HHP had significantly (p<0.05) lower amounts of ethanol (except for day 0) and lower PPO activity in comparison with the other treatments. In conclusion, HHP prevented the fermentation of the products, while although PPO activity was not totally inhibited, it was significantly reduced after this treatment. Therefore, HHP can be regarded as a promising treatment when applied in combination with other hurdle factors to control enzymatic browning and extend the shelf life of fresh cut peaches. Our future studies will be focused on the effects of HHP on other characteristics of the product such as sensorial and nutritional properties.