Study of physiological and textural properties of roasted peanuts defatted by an innovative oil extraction process. Correlation with consumer evaluation
Abstract The growing demands for novel low fat products and health conscious awareness posed a strong incentive to develop a new efficient defatting process of high quality. In this study, mechanical oil extraction, reconstitution by soaking and roasting were conducted on peanuts followed by quantitative and qualitative studies on the morphological and textural properties of the defatted grains to investigate the best extraction parameters (water content, pressure, processing duration) The novelty of this defatting process lies in the use of a specific separation material to avoid irreversible deformation and damage. Instrumental results and consumer evaluation were extremely correlated and findings showed that defatting promotes better grain appearance and increase in expansion ratio, hardness, friability and work required to crush the roasted peanuts that become less crunchy. A multiple optimization, using Response Surface Methodology, resulted in the following optimal conditions: 13.2% d.b. water content, 12 MPa pressure and 19.2 min processing duration. Industrial relevance This study was performed within the Lebanese food project and low fat peanuts were produced in an industrial environment. The work described is innovative in the process implementation and design, thus, results were recently patented under the following publication numbers LB 10,492 and LB 10,493. This article reveals a novel process of defatting called MEPPI "Mechanical Extraction Preserving Product Integrity" applied on hydrated peanuts (7 to 13% d.b. using mechanical expression method at pressures varying between 4 and 10 MPa for different processing durations (10 to 30 min) The additional advantage of this process is that high oil extraction yields (attaining 70 to 80% have been obtained without any recourse to conventional polluting agents such as chemicals (hexane, petroleum ether,.etc. Only mechanical pressing and hydration by soaking have been used during this healthy, eco friendly and cost effective defatting process. By applying this new process, higher oil yields have been achieved with lower processing times (3 4 min) and lower pressures Previous defatting processes were abandoned by the industries as they yielded high percentages of broken and cracked nuts with a harsh texture. Contrariwise, the novelty of this study lies in the use of a specific separation material to avoid irreversible deformation and damage during defatting and to preserve by that the appearance and texture of the finished product. The results of the present study were significant and would be helpful for the food industries as the textural and morphological quality of the new product was studied and the process parameters were optimized for a better acceptance by the consumers. These results demonstrated that this novel process has successfully found solutions to health conscious consumers who are in need of high protein crunchy snacks but of reduced fat, and to food industry by having developed a cost effective method in comparison to current applications. This innovative process can have a broader perspective by applying it to other snack products in order to reduce their fat content while preserving shape integrity, without using any chemical agent.