Enhancement of lime oil extraction using ohmic pretreatment = การเพิ่มประสิทธิภาพการสกัดน้ำหอมระเหยจากเปลือกมะนาวด้วยการบำบัดเบื้องต้นด้วยวิธีโอห์มมิค


เอกรินทร์ โกวิทยา


วิทยานิพนธ์. (2012) 98 หน้า



Lime peel is one of the main by-products of lime juice processing. The peel could be used to produce lime essential oil, which is widely used in the flavor and cosmetic industries. Although there are many techniques for essential oil extraction, the yield is still low, i.e., 0.2 ml/100 g for hydrodistillation, a common method used in lime oil extraction. This research hypothesized that ohmic pretreatment may enhance tissue permeabilization and thus increase the efficacy of lime oil extraction. Ohmic heating system for solid foods was developed and the effects of electric field strength (E) and temperature (T) on the degree of tissue damage and yield of extracted lime oil were investigated. The degree of tissue damage is reported in terms of the conductivity disintegration index, Z. Four levels of electric field strength, i.e., 25, 50, 75 and 100 V/cm, and four levels of cut-off temperature, i.e., 30, 40, 50 and 60 °C were explored. The results indicated that, for all field strengths, an increase in the treatment temperature yielded a higher degree of tissue damage. At T≤50 °C, ohmic heating at E ≥75 V/cm resulted in a significantly higher degree of tissue damage than the treatment at E ≥75 V/cm (p<0.05). At T= 60 °C, maximum tissue damage, i.e., Z = 0.33-0.36 was obtained and there was no significant difference in the degree of issue damage of the sample treated at E ≥50 V/cm. Moreover, ohmic heation at E = 50 V/cm and T = 60° C resulted in 50% increase in the yield of lime oil obtained by hydrodistillation; without ohmic heating, only 0.19 ml of lime oil was obtained from 100 g of fresh lime peel. Similar results were obtained at 75 and 100 V/cm treatments. These results also illustrated the relationship between the degree of tissue damage and extraction yield, i.e., the higher hte degree of tissue damage, the higher the extraction yield. Thus, ohmic heating could be used as a pretreatment to enhance essential oil extraction. This enhancement may be due to electroporation effect and thermal softening of tissues during ohmic heating