PEPPERMINT OIL YIELD AND COMPOSITION FROM MINI AND INDUSTRIAL DISTILLERIES

Peppermint (Mentha pi perita L.) oil yield and composition from miniature research distillation equipment were compared to that from large commercial distilleries. The mini-stills process small, 10-lb samples in contrast to the 8-ton tubs used by industry. A 2-acre, furrow-irrigated field of peppermint, cultivar 'Black Mitcham', was sampled prior to harvest in 1992 and 1993 at 38 and 59 locations, respectively. In 1992, the mean oil yield of the subsamples (43.0 lb/a) agreed closely with the whole-field yield (41.3 lb/a). The subsamples had a high variability in dry matter (CV=33 percent) and oil yield (CV=25 percent). In 1993, mean oil yield (54.8 lb/a) also agreed closely with the whole field yield (55.2 lb/a). The 1992 oil constituents for all 38 samples were compared against a composite of the same, and against the single whole-field measurement from the large distillery. Unlike yield, oil composition was different between the whole field and small samples, probably due to incongruencies in time between harvest and distillation, the presence or absence of chopping, and/or still size