Production of instant soup flour from potato peels

Abstract

Potato peels are considered waste products from the potato processing industry in Uganda. However, potato peels have a lot of benefits including being a good source of energy, minerals, vitamins, and fibre and can be used in the production of several value-added products. In Uganda, the potential of using potato peels in production of value added products has not yet been explored. This study therefore focused on using potato peels as a main ingredient in production of an instant flour for making soup. The potato peels were washed and subjected to two treatments namely heating at 61ᵒC for 10, 20 and 30 minutes and steaming for 5, 10 and 15 minutes. The heated peels were then oven dried at 100ᵒC for 7 hours, milled using a hammer mill and sieved using a 250-micron sieve. The functional and physicochemical properties of the potato peel flour were determined using standard methods. The potato peel flour with highest water absorption capacity among the heated and steamed potato peels was used in the formulation of instant soup; and after proximate composition and sensory evaluation was determined using standard methods. The oil absorption capacity (OAC) of potato-based soup flour from peels heated at 61 oC varied from 261.2 to 195.4%. The oil absorption capacity of the potato-based soup flour from peels steamed ranged from 258.3 to 205.4 The water absorption capacity of the potato-based soup flour from peels heated at 61oC ranged from 365.3 to 287.0%. The water absorption capacity of the potato-based soup flour from peels steamed ranged from 296.5 to 280.1%. The swelling power of the potato-based soup flour from peels heated at 61oC ranged from 2.1 to 2.2%. The swelling power of the potato-based soup flour from peels steamed ranged from 2.3 to 1.9%. The water absorption index of the potato-based soup flour from peels heated at 61oC ranged from 5.2 to 5.5%. The water absorption index of the potato-based soup flour from peels steamed varied from 4.0 to 4.8%. The water solubility index of the potato-based soup flour from peels heated at 61oC ranged from 7.4 to 10.7%. The water solubility index of the potatobased soup flour from peels steamed ranged from 9.3 to 15.1%. The pasting properties showed that the flours from the potato peels heated at 61oC for 10 minutes showed the highest peak viscosity (457cp), trough (426cp), setback(411cp) and final(837cp) viscosity. The flours from the potato peels steamed for 5 minutes had the highest peak viscosity (641cp), trough(501cp), breakdown(140cp), setback(702cp) and final(1203cp) viscosity though the control: reference sample showed the highest pasting properties. The peak time ranged from 5.73 to 7.00 minutes with the reference sample having 5.73 minutes and the others having 7.00 minutes. The proximate composition of the formulated potato peel flour had a higher fibre content of 5.94%, ash content of 10.28%, fat content of 3.10%, protein content of 13.89% and carbohydrate content of 56.72%. The flour also had a 7.08% moisture content below the recommended flour moisture content of 8% as recommended by Jay (1978). The v soup with formulation two (75% peel flour) from the potato peels steamed recorded the highest acceptability score for appearance, colour, thickness, mouthfeel and overall acceptability. The physicochemical and functional properties of the flours were influenced by the heat treatments and the steaming process with 75% peel flour (formulation two) gave the most acceptable flour. The study findings indicated that potato peels are suitable raw materials for instant flour that can be used in production of soup.