1. 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:
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):
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 ;