Reclamation of Used Edible Oil

Abstract

Although the abolition ratio of edible oil depends on usage and where it is used, the amount of abolished oil in Japan seems to be vast; presumably, 20% of annual consumption of edible tallow vegetable oil, 2.5 million tons (1), is abolished at present. But one half of the used oil is rarely recovered because of domestic use (2). In spite of enthusiastic efforts of some groups making soap from it, most used frying oil is discarded after it is solidified with a gelling agent or bottled or is discarded directly to soil or kitchen drains (3). Thus, complete recovery of used edible oil will be a difficult goal to achieve immediately. The rest of the used oil is generated from food manufacturing industries, restaurants, supermarkets, and other food-related businesses and recovered by renderers, oil collectors, and blenderers, then classified by appearance and other properties and reused after simple treatments or burned. In short, some used edible oil ends up as a fatty acid source, feed oil for animals, paint, ink, fuel oil, or soap or is burned/discarded (2,4). Insufficient reuse of recovered oil is primarily due to tough competition between the price of good-grade oil coming from fancy restaurants and other such sources and the cost of refining low-grade, poorcolored oil (Gardner color 11), as well as to the relationship between the demand and the supply of both oils.

Effects of Deteriorated Frying Oil in SHR/NDmc-cp Rats

“…The mean body weight was 195. 1 13.4 g. Animal care and handling were in accordance with the Ethical Agreement Concerning Care and Use of Laboratory Animals for Research and Education, KobeGakuin University.…”

Color Deterioration of Oil during Frying

“…(C/A) n C At the final stage (after final addition of (A C), oil is used for B h and banned) initial portion of oil decreases to A(C/A) n+1 , and last added virgin oil, the most fresh portion, decreases to (A C)C/A, the second last added virgin oil to (A C)(C/A) 2 , and so on. Sum of all the portions makes C. For example, if A = 20 L, B = 5 h (frying time per day; virgin oil is added daily in the morning from the second day on), and C = 17 L, at the end of the 5th day the whole batch of oil is banned.…”

Reclamation of Used Edible Oil. II

“…One hundred grams each of alkali-refined oils SB, SBW, SM, SA, and SAN were poured into separate 500 mL four-necked flasks and heated to 115-120 , after which 5% hydrogen peroxide was added carefully (to avoid excessive bubbling) under stirring at 1000 rpm (3). After one hour of high agitation, the oil was heated at 130 for 30 min at 1 kPa to dry.…”

“…Chaotropic reagents disturb lipophilic interactions and increase the solubility of nonpolar substances in water (22). Polar proteins in recovered oil were removed easily by the first filtration, but the remaining proteins were less polar and hard to remove despite repeated filtration (3). When the Hofmeister theory is applied to proteins in oil, it is highly possible that barium hydroxide particularly destabilized lipophilic proteins and made them removable by washing and filtra-…”