Effects of processing factors on the quality of mechanically expressed Moringa (Moringa oleifera) oil: A response surface approach

Abstract

Edible unrefined oils produced by expellers need to possess high quality attributes; therefore, the effects of processing factors on the quality of mechanically expressed moringa oil were investigated. A 4 × 5 Central Composite Rotatable Design was adopted for the experiments. Processing factors were moisture content, heating temperature, heating time and applied pressure. Oil quality criteria such as FFA, oil impurity and colour were determined. Data analyses were done using multiple linear regression at p = .05. The FFA, impurity and colour intensity ranged from 2.42–7.40 mg/KOH/g, 5.70–7.60 LU and 2.12–3.20% respectively and fell majorly within acceptable limits. Mathematical models were developed relating processing factors to oil quality. Coefficients of determination (R2) for the FFA, impurity and colour intensity were .94, .98 and .99 respectively. Deviations between experimental and predicted values were low and ranged from 0.01–0.68, 0.01–0.12 and 0.01–0.12 for the FFA, colour intensity and impurity respectively. Practical applications Edible unrefined oils being produced by expellers need to possess high quality attributes. Applied pressure, heating temperature, heating duration, and moisture content affect the quality of vegetable oil expression and these factors need to be controlled during expression process. Free fatty acid (FFA), color intensity, and oil impurity are some of the most important oil quality parameters. FFA is responsible for rancidity; color is the most obvious product characteristic evaluated by any consumer of vegetable oil; while oil impurity affects the sensory characteristics of the oil. As the mechanical method of oil expression has gained high importance in modern vegetable oil industry, it is necessary to determine the effects of processing factors on the quality of the expressed oil. In this study, mathematical models were developed to predict the physico‐chemical properties of mechanically expressed moringa oil at various processing conditions. This would serve as useful data to moringa oil processors.

Influence of processing conditions on some physical characteristics of vegetable oil expressed mechanically from Pentaclethra macrophylla Benth kernels: Response surface approach

“…The oil impurities increased with moisture content and heating time (Figure ); this may be due to the fact that moisture constitutes about 87% of volatile impurities which accounts for noticeable influence on moisture content, this is in agreement with Akinoso, Igbeka, and Olayanju () and Fakayode et al ().In Equation , moisture content and heating temperature caries negative sign but moisture content is the most significant. Second order of heating temperature and interaction between heating duration and temperature are negligible using three significance figures.…”

“…Defective kernels were discarded while selected ones were kept in airtight polythene bags. The kernels were further conditioned to desired moisture levels by dehydration and rehydration; the mass of water added to obtain desired moisture levels (8, 10, 12, 14, and 16% dry basis) was obtained using Equation (Akinoso, ; Bisht, ; Fakayode et al, ): Where: M is the mass of water added (g), X is the initial mass of samples, y is the initial moisture content of samples, and z is the desired moisture content.…”

“…The oil expression efficiency of mechanical method of oil separation is affected by the condition of the oleaginous biomaterial and other pretreatment parameters; it has an advantage of low initial and operating costs and expressed oil samples are free of hazardous chemical substances (Bamgboye & Adejumo, ; Ibrahim & Ogunwusi, ).Processing and extraction conditions affect oil characteristics, which can also be dependent on other agronomic factors like climatic conditions, soil composition, ascension, and harvesting time (Compaore et al , ; Fakayode, Ajav, & Akinoso, ; Maestri & Guzman, ; Ogunsina, Owolarafe, & Olatunde, ). Independent variables that influence the quality and quantity of vegetable oil expressed mechanically include processing parameters like heat applications (duration and temperature) (Aktas, Gerçekaslan, & Uzlaşır, ; Raba, Chambre, Copolovici, Moldovan, & Copolovici, ; Rahma, Zekhnini, El‐Alem, & Hatimi, ) and moisture content (Fakayode & Ajav, ; Pornpipat, Hattha, & Tantanawat, ; Sarah, Widyastuti, & Ningsih, ; Udoh, Olayanju, Dairo, & Alonge, ; Zheng et al , ).…”

Size characterization of moringa (Moringa oleifera) seeds and optimization of the dehulling process

“…The graded moringa seeds were conditioned to selected moisture content levels using Equation (2) as adopted by Fakayode, Ajav, and Akinoso (). …”

The Potential of Some Moringa Species for Seed Oil Production

“…However, the yields under cold extraction are usually low, corresponding to about 60% of the extractive efficiency obtained with hexane [67,76]. Several parameters can be optimized to maximize recovery, including the seeds' size, moisture content, applied pressure, and temperature [89]. Aqueous enzymatic extraction has also been approached with positive outcomes, with up to 70% oil recovery [90,91], with easier phase separation efficiency when kernels are previously submitted to high pressure treatments, an increasingly common technique in the food industry [92].…”