MECHANISM FOR BLOATER FORMATION IN BRINED CUCUMBERS

The susceptibility of pickling cucumbers to bloater damage during storage in CO2-charged brine depended upon the internal gas composition of the cucumbers before brining. Gas extracted from fresh cucumbers consisted of about 75% N2, 20% O2, and 6.0% CO2. Replacement of that gas with CO2 or O2, reduced the susceptibility of the fruit to bloater damage upon subsequent storage in carbonated brine. Bloater damage was related directly to % N2 and inversely to % CO2 in the internal gas of the cucumbers when they were brined. These and other findings are the basis of the following mechanism we propose to explain bloater formation of cucumbers in brine containing CO2. When cucumbers are brined, liquid clogs the intercellular gas spaces of the tissues that normally permit rapid diffusion of gases in fresh cucumbers. The liquid-clogged layer encloses the internal gases within the fruit and functions as a differentially permeable barrier to N2 and CO2. Since N2 is the predominant gas within the fresh fruit, and since CO2 concentration in the brine is high, a diffusion gradient for CO2 exists toward the fruit interior. CO2, which is much more water soluble than N2, diffuses from the brine into the fruit faster than N2 can diffuse from the fruit. Ultimately, the transfer of CO2 to the fruit interior results in sufficient internal gas pressure due to CO2 plus N2 to rupture the flesh, causing a gas pocket (bloater formation).