The use of mineral oil as a trapping agent for volatiles produced by Ceratocystis moniliformis (Hedg.)

Abstract

Ceratocystis moniliformis grows well in a semi-synthetic liquid medium containing 30:1 glucose:yeast extract, vitamins, and minerals. At 25°C and 100 rpm on a rotary shaker, the culture grows and produces many pleasing and potentially useful fruity aroma-bearing compounds. A sensory evaluation panel described the aromas "banana," "citrus," "fruity," "peach," and "floral" in samples of this culture. However, yields of the compounds that cause these aroma perceptions are low, as their production is limited due to toxicity, or perhaps a feedback inhibition mechanism. Seventeen volatile aroma compounds were tentatively identified by Gas Chromatography - Mass Spectrometry (GC- MS), and of these, the production of isoamyl acetate, B -myrcene, acetophenone, i1-octanol, and geraniol was studied using GC analysis. In an attempt to increase the production of these compounds relative to the production level of aroma-bearing compounds obtained by traditional incubation methods, mineral oil was added to the growth medium as a thin (2 mm) layer. Difficulties in analyzing oil-free cultures made it impossible to directly compare yields in oil-free versus oil-containing cultures. However, the mineral oil acted as a trapping agent, and production of aroma compounds continued in the presence of mineral oil for up to 8 days, yielding from 246 to 2071 ug/100 ml culture of the aroma compounds. The above-mentioned compounds are similar to natural and synthetic essential oil components that are currently used as food flavorants. Thus, aroma-bearing compounds that are produced by Ceratocystis moniliformis may prove to be valuable alternative sources for food flavoring.