Effect of Different Peeling Methods on the Quality Characteristics of Livingstone Potato Flours Ofoeze M.A1,2, Ukeyima, M.T.2,3 and Girgih, A.T.2,3* 1National Root Crop Research Institute Umudike P.M.B 7006 Umuahia, Abia State, Nigeria, 2Centre for Food Technology and Research, Benue State University, Makurdi, Benue State 3Department of Food Science and Technology, University of Agriculture, Makurdi, Benue State Methods Table 4: Quantification (mean values of triplicate) of secondary metabolites of Plectranthus esculentus tuber flour Livingstone potatoes Postharvest losses in livingstone potatoes Flour Tannin (%) Saponin Flavonoid Phenol Alkaloid AP 0.90a 0.38a 0.31a 0.12a 0.61a KP 0.85b 0.37a 0.29a 0.15b 0.73b LP 0.63c 0.23b 0.21b 0.09c 0.53c Analysis Knife peeling (Kp) Lye peeling (Lp) Abrasion peeling (Ap) Peeling time Peel loss Flour yield The percentage peel loss was determined using the difference in weight before and after peeling The average peeling time was recorded for peeling 1kg of tuber The flour yield was done by difference and expressed as percentage of the original weight of the tuber 5% lye Rubbed between the palm Introduction Peeling with knife Soaked 10mins Livingstone potato (Plectranthus esculentus) which is commonly cultivated in Africa belongs to the family of Lamiacea and it encompasses many aromatic plants [1]. These are erect perennial, herbaceous plants that may grow up to 60 cm tall with yellow flowers and lumpy edible tubers at the base of the stem [2, 3]. It is one of the lesser known tropical crops in Nigeria and other Sub- Sahara African countries [3]. It is eaten raw as snack after peeling and washing or boiled and eaten as porridge. This plant is also being used as a functional food due to its perceived therapeutic value in alleviating stomach upset and pain (folklore medicine). Over the years this plant has remained underutilized. One of the reasons for its underutilization is the difficulty in peeling of the tubers which are finger-like shaped (about 5 cm). The farmers of livingstone potato, mostly rural women use abrasion method of peeling that involves rubbing of the tubers between two palms to create friction that enhances peeling [interview]. This method is only used immediately after harvest during the rainy season when the skin has not strongly stuck to the flesh of the tubers. Alternatively, the unpeeled tubers are cooked with potash to ease peeling and then consumed [interview]. Due to the difficulty in peeling, oftentimes the farmers abandon the harvested tubers thus leading to huge postharvest losses. Presently there is dearth of information regarding the processing, quality characteristics and uses of this crop. Vigorous washing with H2O Knife peeled sample Lye-peeled sample Abrasion peeled sample FLOUR SAMPLES Figure 6: Proximate nutritional values of flour of Plectranthus esculentus tuber PHYTOCHEMICAL SCREENING PROXIMATE COMPOSITION FUNCTIONAL PROPERTIES Conclusion This study has shown that lye peeling and abrasion peeling significantly minimized peel losses thereby enhancing the flour yield of the tubers when compared to the knife peeling method of peeling. Thus post harvest losses of livingstone potato could be reduced, if lye peeling and abrasion peeling (if modified) methods of processing are adopted. TANINS FAT BULK DENSITY CHO SAPONINS WATER ABSORPTION CAPACITY (WAC) References ALKALOIDS ASH Allemann, J. and Hammes, P.S. (2006). Effect of photoperiod on tuberization in the Livingstone potato (Plectranthus esculentus N.E.Br. Lamiaceae). Field Crops Research Journal., 98:76-81. 2. Victor, J. T. O. and Charles, E. O.(1991) Chemical composition of livingstone potato( Plectranthus esculentus), Journal of the science of food and Agriculture, 54:215-217.   3. Ukpabi, J.U., Emmanuel, O. and Ogbogu, N.J. (2011). Culinary and Sensory Characteristics of Hausa Potato (Solenostemon rotundifolius) and Livingstone potato (Plectranthus esculentus) tubers in Nigeria. Journal of Stored Products and Postharvest Research 2(16):301-304. 4. Onwuka, G.I. (2005). Food Analysis and Instrumentation. Theory and Practice. Naphtali Prints, Nigeria, 48. Figure1:Abrasion method of peeling Figure 2: Display of livingstone potatoes for sale CRUDE FIBRE GELATION CAPACITY FLAVONOIDS OIL ABSORPTION CAPACITY (OAC) CRUDE PROTEIN Objectives Results Evaluate the efficiency of different peeling methods To evaluate the effect of different peeling methods on the quality characteristics of livingstone potato flour To determine the functional properties and phytochemical profile of livingstone potato flour. Table 1: Flour yield, Peel loss and peeling time of the fresh experimental sample Flour Flour yield (%) Peel loss Peeling Time (minutes/kg) LP 31.34a 23.23b 15b Kp 23.75b 37.47a 145a AP 31.71a 23.36b 23.66b Acknowledgement Materials and Methods We are grateful to management and staff of National Root Crop Research Institute (NRCRI), Umudike, Abia State, Nigeria, The Centre for Food Technology and Research (CEFTER), Benue State University, Nigeria and Federal University of Agriculture Makurdi Benue State Nigeria. About 15kg of the fresh livingstone tubers were obtained from the Minor Root Crop Programme of the National Root Crops Research Institute (NRCRI), Umudike. The tubers were then sorted and cleaned. They were divided into 3 lots and subjected to different peeling methods: Knife peeling (KP), Lye Peeling (LP) and Abrasion peeling (AP). Table 2: Functional properties (mean values of triplicate) of dehydrated flour samples of Plectranthus esculentus tuber Flour Bulk Density Water Absorption Capacity Oil Absorption Capacity Solubility in water (%) Gelation Temp (°C) LP 0.85a 2.16a 1.60b 11.60a 74.33a KP 2.26a 2.10a 13.04a 73.66ab AP 0.87a 2.30a 12.85a 76.66b Figure 3: Livingstone potato tubers Figure 4: Knife peeling method Figure 5: Peeled livigstone potatoes Ofoeze, Miriam Ahunna, Centre for Food Technology and Research, Benue State University, Makurdi, Benue State mimiofoeze@gmail.com ; +2347030470104