Page 402 - Biosystems Engineering

Extraction, Refining, and Stabilization of Edible Oils 379

in a continuous countercurrent device. However, there has been the
possibility of negative effects at high temperatures during deodoriza-
tion. Ziegler et al. worked on deodorizing and deacidifying peanut
18
oil using CO . The efficient deodorization and deacidification of an
2
actual crude oil pressed from roasted peanuts and accomplished by
extraction with CO was done at 47°C and 20 MPa.
2
Extraction with deacidification is expensive, especially with
oils with high initial acidity or where the quality and purity of the
extracted components are important. Good manufacturing prac-
tice also implies the following: use of stainless steel equipment,
careful deaeration at <100°C before heating to the final stripping
temperature, use of oxygen-free steam, and strict feedstock speci-
fications (typically Fe 0.1, Cu 0.01, P S, bleaching earth 5 mg/kg oil
maximum).

13.5 Stability of Edible Oils and Antioxidants
Lipid oxidation is primarily responsible for the deterioration of the
sensory and nutritional quality of foods. This process, known as
rancidity, is responsible for economic losses associated with the
deterioration of edible oils. When this deterioration occurs, the oil
or the oil-containing food becomes unacceptable to consumers
because of off-flavors and unpleasant odors associated with the for-
mation of oxidized products. In addition, many of these oxidized
products are considered unhealthy and harmful. One way of pre-
venting lipid oxidation and enhancing the shelf-life of oils and oil-
containing foods is by adding antioxidants. These antioxidants may
be indigenous to the food product or added after processing.
Because of health concerns associated with the use of synthetic anti-
oxidants, there has been an increasing interest in natural antioxi-
dants. This chapter briefly reviews lipid oxidation and discusses the
efficacy of natural antioxidants in minimizing or preventing oxida-
tive changes from occurring.
Food components such as lipids are very susceptible to oxidation,
which results in detrimental changes to the color, odor, and nutritive
value of the affected food products. Antioxidants prevent such
changes by retarding or slowing down the process of oxidation or
rancidity.
Fat deterioration can be divided into four types 19
1. Hydrolysis—leads triacylglycerols to form free fatty acids and
glycerol, often characterized by a “soapy flavor.”
2. Rancidity—a term widely used in the food industry that nor-
mally covers a large number of objectionable off-flavor volatile
components generated from the auto-oxidation of polyun-
saturated fatty acids.