Food or edible material: processes – compositions – and products – Inhibiting chemical or physical change of food by contact... – Treating liquid material
Reexamination Certificate
2002-03-05
2003-10-28
Paden, Carolyn (Department: 1761)
Food or edible material: processes, compositions, and products
Inhibiting chemical or physical change of food by contact...
Treating liquid material
C426S417000, C426S423000
Reexamination Certificate
active
06638551
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to processes and compositions for purifying edible cooking oils. The compositions and processes of the present invention remove various oil contaminants such as color bodies, polar materials, soaps, fatty acids and trace metals, thereby improving the quality of, and extending the usable life of, the oil.
2. Description of Related Art
Edible frying oils, which are typically used to fry various foods such as chicken, French fries, potato chips, and other meat, vegetable or dough products, can decompose over time and with use due to the formation and acquisition of various contaminants released or produced during cooking. Contaminants such as water, soaps, polar compounds, polymers, free fatty acids, color bodies, and trace metals build up in the oil over time and contribute to the degradation and increased instability of the oil. As these contaminants build up in the oil, the oil can become discolored, develop a displeasing smell and taste, begin to foam due to the formation of soaps, produce heavy smoke at normal cooking temperatures, and/or quickly become rancid and unusable.
Without treatment this degeneration typically occurs rapidly, requiring complete replacement of the used oil with fresh oil as often as every 2 or 3 days, thereby significantly raising the cost of production of fried foods. The FDA Food Safety and Inspection Service (FSIS) Meat and Poultry Inspection Manual provides guidelines that must be observed by industrial meat and poultry fryers. For instance, Section 18.40(a), directed to frying of meat, explains that the suitability of fats and oils used for deep fat frying “can be determined from the degree of foaming during use or from color, odor, and flavor.” Additionally the Manual indicates that “fat or oil should be discarded when it foams over the vessel's side during cooking, or when its color becomes almost black as viewed through a colorless glass container.” Of course, the amount of time that fats and oils may be used for frying varies depending upon a number of factors, such as the type and volume of food fried, the temperature, the quality of new oil or fat added and the frequency of addition or new oil or fat, as well as the treatment used for decontamination of the oil.
The various contaminants that accumulate in the oil create several problems with the oil and the food fried in the oil. For instance, the high cooking temperatures and the water released from the food being fried causes the formation of free fatty acids. The free fatty acids combine with various trace metals in the oil to form soaps. Soaps not only cause unpleasant foaming of the oil, which can present a safety hazard for those operating the frying equipment, but also cause the food to absorb more of the oil during cooking. The absorption of more oil not only results in a greasier, less desirable product but may also result in the food product becoming overcooked, giving it a harder or tougher consistency than desired.
The accumulation of polar compounds is another serious problem in used oil. Polar compounds contribute to unpleasant taste and increased oxidation which leads to the oil becoming rancid and completely unusable. A build up of polar compounds in the oil also leads to a reduction in the smoke point of the oil. Carmelization, caused by buildup of color bodies that turn the oil a darker color, produces fried food with a darker, overcooked and unappealing appearance. Trace metals such as magnesium, phosphorous, copper, and iron also increase the oxidation of the oil by reacting with oxygen in the air to catalyze the oxidation process. This increases the peroxide value of the oil indicating increased instability and promoting further oxidation and rapid spoiling of the oil.
Combinations of impurities, such as free fatty acids and polar compounds can result in the formation of a film on the surfaces of the frying equipment. Additionally, buildup of fat and other impurities will reduce the smoke point of the oil, causing the oil to smoke heavily at operating temperatures of around 300° F. To prevent the problems associated with the buildup of these contaminants, oil must either be replaced often, or treated to remove or neutralize the contaminants, thereby extending the life of the oil.
Known cooking oil treatments, or “frying aids,” have various drawbacks. For instance, some treatments do not address more than one or two of the above-mentioned problems, while others fail to significantly extend the life of the oil, and some even introduce additional health and/or safety concerns. One method directed to reducing soap formation involves heating the oil to 300° F. and mixing the oil with a composition of water, a porous carrier and a food-compatible acid. Similarly, another method involves contacting the oil with a food-compatible acid to help counteract soap formation. Both of these methods help eliminate soaps, but fail to address the other problems caused by contaminants present in the oil.
Another method for treating oil attempts to reduce the accumulation of free fatty acids and raise the smoke point of used cooking oil by mixing the used oil with an adsorbent of alkaline earth oxides or carbonates, which adsorbent is then separated out of the oil after mixing for between 3 and 15 minutes. In another method, used cooking oil is contacted with a composition of activated clay or magnesium silicate and between 15% to 75% weight of gel derived alumina to reduce both the amount of free fatty acids present in the oil as well as remove color from the oil. Yet another method for reducing the fatty acid content of used oil discloses contacting the oil with hydrated magnesium silicate. Once again, these methods treat only one or two problems with the used oil, thereby failing to significantly extend the overall shelf life of the oil.
One method for treating oil uses various silicas and acid-treated silicas to remove trace metals and phospholipids from used cooking oils, but fails to remove any other contaminants from the oil. In another treatment the used oil is contacted with a composition of 60% to 80% amorphous silica and 20% to 40% alumina. However, this method is ineffective in extending the life of the oil beyond about 5-10 days because the treatment fails to adequately reduce the levels of various contaminants. Moreover, each treatment with this product absorbs approximately 6 oz of oil for each 6 oz of the composition, thereby requiring frequent addition of more fresh oil.
Another method utilizes a metal-substituted silica xerogel having pH of at least 7.5 and optionally combined with an organic acid. This method is directed to removing contaminants such as phospholipids, soaps, metals and chlorophyll from glyceride oils. However the silica xerogel composition does not effectively decolorize the oil, and smoking of the oil occurs within about 5 days of use. As a result, oil treated with the silica xerogel will still require replacement after only about 5 to 7 days of use and treatment with the silica xerogel.
A commonly used treatment for frying oils is Silasorb™ (Celite corporation, Denver, Colo.), a synthetic calcium silicate. This treatment lowers free fatty acids in the oil by a combination of adsorption and neutralization. However, the neutralization of a fatty acid with an alkaline metal produces a fatty acid soap and may result in uncontrollable foaming, leading to safety hazards for operators of frying equipment. Additionally, Silasorb contributes to the darkening of the oil.
Yet another method directed to removal of free fatty acids from used oil involves treating a used cooking oil or fat with a composition of magnesium silicate and at least one alkali material. Whereas many other treatments involve contacting the oil with a composition that absorbs the contaminants in the oil, the composition of this method works at least in part by neutralization. For instance, the magnesium silicate acts as a bleaching agent to change the color of the color bodies within the oil, thereby lightenin
Levy Ehud
Li Cang
Tazi Mohammed
Gray Bruce D.
Kilpatrick & Stockton LLP
Selecto Scientific, Inc.
LandOfFree
Methods and compositions for purifying edible oil does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Methods and compositions for purifying edible oil, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Methods and compositions for purifying edible oil will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3130366