Study of the possible chemical and biochemical events that affect the increase of the acidity in process extraction of maize oil

Abstract

The present work has the objective of studying the chemical and biochemical factors that promote the increase in acidity in oil produced from maize grains during storage in silos, the degermination and palletizing. A water activity ((aw) of 0,805 ± 0,003 was determined in maize grains, a peroxide index (IP) of 6,75 ± 0,20 in degermination, and a % acidity of 4,07 ± 0,06 in palletized oil. The lipase activity was performed by potentiometry in the presence of bovine bile and olive oil. The enzymes were extracted in a 1% (p/v) saline medium at 13000 rpm (15 min), resulting in an activity at pH 7,6, 36 °C of 2.6 meq/g min in samples without physical processing treatments, and 0,02-0,04 meq/g min in samples submitted to processing . A bifactorial design and central stars surface type composition studied the hydrolytic deterioration of the oil. The water flow was significant. The mathematical equation obtained was: % acidity = 4.88 - 0.741557A, with a regression coefficient of (R2) 91.76%.

Keywords

• acidity
• lipase
• maize grain
• maize oil