Quality Characteristics Of Palm Oils Produced From Improved Traditional, Artisanal, Medium And Large Scale Processes

ABSTRACT

The quality of palm oil depends on the method of extraction. Mechanized methods of extracting palm oil result in better oil quality. In Ghana over 80% of palm oil is produced by small scale processors whose lack of mechanization results in poor oil quality. A study conducted in 2011 resulted in the development of an improved traditional process (ITP) to augment the quality of palm oil from the small scale. This study sought to compare palm oils from different processing scales to ITP oil to identify gaps in quality for further improvements. The objective therefore was to assess the quality characteristics of palm oils produced from the improved traditional process, small (artisanal), medium and large scale processes. Palm oils from 8 different processing methods were purposively sampled. Physico-chemical analysis which included; moisture, impurities, colour, Free fatty acids (FFA), peroxide value, iodine value and saponification value were conducted on both fresh and stored palm oil samples. A descriptive sensory analysis was also done by a trained panel to identity, describe and quantify perceivable palm oil sensory attributes. Analysis of Variance (ANOVA) was carried out to establish the effects of the extraction method on physico-chemical parameters. Principal Component Analysis (PCA) was used to identify major sensory attributes of the different palm oil samples. FFA which is the key quality index in determining oil quality varied among processing methods. Palm oil sample from the large scale processing facility where fruits are harvested and processed almost immediately (L1) had the lowest FFA of 2.51%. It was the only sample that met the standard of 5% maximum FFA. ITP samples recorded 5.93% while oil samples from the small scale had the poorest quality with over 31% FFA. Moisture values for all samples except L1 (0.1%) ranged from 0.5 - 1.15% and may alter the physical state of the oils. Palm oil samples from the spindle press (SSP) and hydraulic press (SHP) were not clarified and had very high amounts of impurities (0.45%). The range of values obtained for both iodine value and saponification value (50 – 55 and 190 – 210 respectively) identifies the oils as palm oil. Stored palm oils deteriorated with storage especially after the first four weeks. Deterioration in L1 was minimal. Orange - red colour, turbidity, rancidity, smoky, burnt, bitter taste, sweet taste, mouth coating and roughness were the descriptors used to identify the perceivable palm oil sensory attributes. Oils from the small scale were predominantly rancid, oils from the medium scale and the improved traditional process were smoky while oils from the large scale were fresh. Palm oils from the large scale had better physico-chemical and sensory quality and longer shelf stability due to mechanized processing which is more efficient. Boiling of fresh fruit bunches (FFB) should be done to facilitate fruit stripping so that fruit storage which is the major cause of FFA accumulation can be avoided. Careful clarification and the introduction of a drying process would be necessary to extend shelf stability of palm oil produced at the small and medium scale levels.