Reducing Ochratoxin A Content in Grape Pomace by Different Methods

Abstract

Grape pomace (GP) is the residue of grapes after wine making and is a valuable source of dietary polyphenol and fiber for health promotion. However, studies found the presence of ochratoxin A (OTA) in GP at very high concentrations, which raises a safety issue in the value-added utilization of GP. This study evaluated the effects of thermal pressure, baking, acid and enzymatic treatments on OTA content in GP. Thermal pressure treatment was conducted with wet GP at 121 °C for 10–30 min in an autoclave; acid treatments were conducted with hydrochloric acid, acetic acid, citric acid, and lactic acid, respectively, at 50 °C for 24 h. Baking was conducted using a cookie model. For enzymatic treatment, purified OTA solution was treated with carboxypeptidase A, alcalase, flavourzyme, pepsin, and lipase, respectively, and the effective enzymes were selected to treat GP. Results show that autoclaving for 10–30 min reduced 19–80% of OTA, varying with treatment time and GP variety. The effectiveness of acid treatment was similar to that of autoclaving and varied with acid type and GP variety. Baking increased the detectable OTA. Among all tested enzymes, carboxypeptidase A was the most effective in reducing OTA, followed by lipase and flavourzyme, but their effects were significantly lower in GP samples.

Determination of Ochratoxin A and Ochratoxin B in Archived Tokaj Wines (Vintage 1959–2017) Using On-Line Solid Phase Extraction Coupled to Liquid Chromatography

“…Ochratoxin A is a very persistent mycotoxin and is not considered to be reduced during wine aging. Several studies have dealt with its reduction throughout the winemaking process using solid mass adsorption and fermentation or by an additional laborious process [35,36]. Terminating any processes before storing, OTA is stable in an acidic medium.…”

Practical Strategies to Reduce Ochratoxin A in Foods

“…Yu et al [ 114 ] determined the effect of enzymatic processing on the fate of OTA in grape pomace or OTA in buffer solution. When OTA buffer solution (pH 5.4) was treated with flavozyme, lipase, and carboxypeptidase A at 37 °C for 24 h, 36, 60, and 100% of OTA reduction was observed, respectively, while these enzymes reduced 10.2% (lipase) and 18.3% (carboxypeptidase A) of OTA in grape pomace, and flavozyme did not reduce any OTA [ 114 ]. They also showed that this difference was due to the polyphenols in grape pomace that can inhibit different hydrolytic enzymes such as proteaseand lipase [ 114 ].…”

“…When OTA buffer solution (pH 5.4) was treated with flavozyme, lipase, and carboxypeptidase A at 37 °C for 24 h, 36, 60, and 100% of OTA reduction was observed, respectively, while these enzymes reduced 10.2% (lipase) and 18.3% (carboxypeptidase A) of OTA in grape pomace, and flavozyme did not reduce any OTA [ 114 ]. They also showed that this difference was due to the polyphenols in grape pomace that can inhibit different hydrolytic enzymes such as proteaseand lipase [ 114 ].…”

“…Therefore, Yu et al (2020) investigated the effect of autoclaving on OTA fate in grape pomace. The autoclaving conditions were at 15 psi and 121 °C for 10, 20, and 30 min, and the reductions in OTA in different varieties of grape pomace were about 19.2–67.6%, 37.6–80.0%, and 43.8–78.0% at 10, 20, and 30 min, respectively [ 114 ]. This study also determined the effect of baking at 178 °C for 20 min on OTA fate in a different variety of grape pomace cookies, but what was very interesting was that all cookies showed higher OTA contents in the range of 45.4–69.8% than their corresponding doughs that contained 8.8 ng/g of OTA (dry basis) [ 114 ].…”

“…Yu et al [ 114 ] examined the effect of organic acids on the reduction in OTA in three grape pomaces of cabernet franc, cabernet sauvignon, and chardonnay, at pH 2 and 37 °C for 24 h. While the results were variable, the reductions in OTA in wine pomace by acetic acid, citric acid, lactic acid, and hydrochloric acid were 59.8, 56.8, −4.4, and 8.1% in cabernet franc, 14.7, 56.8, 67.2, and 62.8% in cabernet sauvignon, and 61.4, 20.2, 46.4, and 25.0% in chardonnay, respectively [ 114 ]. Even though the pH was as low as 2 in this study, such low pH levels in foods are rare except lemon juice, beer, vinegar, etc.…”