EP0785249A2

EP0785249A2 - Method for neutralizing and deodorization of vegetable oils, especially for food industry

Info

Publication number: EP0785249A2
Application number: EP96250157A
Authority: EP
Inventors: Ján Chrbet; Jana Chrbetová
Original assignee: Bell sro
Current assignee: Bell sro
Priority date: 1995-12-27
Filing date: 1996-07-12
Publication date: 1997-07-23
Also published as: SK278951B6; EP0785249A3; CZ37696A3; CZ283188B6; HU9602006D0; HUP9602006A2; SK165695A3; PL315473A1

Abstract

A method of neutralizing and deodorization of filtered and/or settled raw and/or degummed and blanched vegetable oil, wherein vegetable oil heated to the temperature of l85 to 255 °C, is supplied to an unheated short-way drop vacuum evaporator, and the neutralizing and deodorization of oil is realized by means of a distillation of a thin film dropping down, at pressure of 2Ol to l OOO Pa and at the temperature of l8l to 250 °C. A physical neutralizing and deodorization of vegetable oil pursuant to the presented invention enables to produce oil with a high durability, biological and physiological value, as well as with sensoric properties of a high quality.

Description

Sphere of the Art

The invention relates to a method of refining which resides in neutralizing and deodorization of vegetable oils, designed, above all, for food purposes and gained by pressing and/or extracting; said method is based on physical principles.

State of the Art

A refining of vegetable oils comprises in fact four technological operations: degumming, neutralizing, bleaching and deodorization; said operations are applied in various modifications.
Several processes are applied at present for neutralizing, i.e. for removing from vegetable oil free fatty acids which affect its stability in an undesirable way, as well as for deodorization, i.e. for removing undesirable odours and tastes.
The most popular method for neutralizing resides in utilizing a chemical process, when an aqueous solution of an alcali lye affects vegetable oil which results in neutralizing free fatty acids comprised in oil, i.e. lye reacts with free fatty acids, and soaps are formed. Said soaps have an emulgating effect and in this way a loss of oil is increased; more over, lye affects vegetable oil in a negative way because it caused a partial hydrolysis of oil, which results in further losses, and more over it accelerates subsequent reactions, especially multiple bonds of unsaturated fatty acids, i.e. of oileic acids, linoleic acids, linoleinic acids in acyls of triglicerides, which decreases oxidizing and sensoric stability of oil, as well as its biological value.
After a chemical neutralizing of vegetable oils, there is used a distillation with steam at a high temperature in vacuum for deodorization which represents a process needing much energy.
There are also known neutralizing processes and deodorization ones of vegetable oils on the basis of a physical refining.
By means of a vacuum distillation with steam at a pressure of 300 to 8OO Pa, there are removed free fatty acids according to processes described in US patents No. 2 980 717, 2 991 298 and 3 206 487. Drawbacks of said methods reside in high investment costs and operational ones at producing steam and vacuum.
By means of a vacuum distillation without using steam from a thin wiped-off film of a heated vacuum evaporator at pressures of l to 2OO Pa and at temperatures of l30 to 180⁰C, there can be removed free fatty acids and aromatic agents from vegetable oils pursuant to the method protected by the patent SK 277 771. In said case there also exist high investment costs and operational ones at the neutralizing process and deodorization one The high price of the apparatus is affected especially by a vacuum circuit and by a freezing system of vapours of aromatic agents. The proper evaporator is a complicated and expensive machine, especially with respect to the production of a wiping off teflon system and machining accuracy of the wiping off surface. As there is used a heated vacuum evaporator, the evaporation surface is heated and oil is burned onto the evaporation surface; more over, polymerized layers formed mainly during putting aside (oil dries out) prevent the film from a heat transfer. Said drawbacks can be obviated considerably by the method for neutralizing and refining of vegetable oil pursuant to the presented invention.

Principle of the invention

The principle of the invention resides in the fact that a filtered and/or settled raw or degummed and blanched vegetable oil, heated to the temperature of l85 to 255 °C, is supplied to an unheated short-way drop vacuum evaporator, and the neutralizing and deodorization of oil is realized subsequently in the above mentioned evaporator by means of a distillation of a thin film dropping down, without using steam, without heating and without wiping off, at pressures of 2Ol to l OOO Pa and temperatures of l8l to 250 °C.
For heating vegetable oil, it is advantageous to use two stages, viz. vegetable oil is preheated in a preheater to the temperature of lOO to l70 °C and finish heated in a heater to the temperature of l85 to 255 °C.
For preheating the vegetable oil, it is advantageous to use neutralized and deodorized vegetable oil leaving the above mentioned evaporator.
The method according to the invention provides, in comparison with methods described in the State of Art, many advantages.
When performing the method according to the invention, it is not necessary to heat the evaporation surface, because into the vacuum evaporator there is supplied oil already heated. Oil, sufficionally heated, is cooled down only a little after the distillation, and it is not necessary, even in the surroundings of a low pressure, to go on in stressing it thermally by further heating. As the vacuum evaporator is not heated, oil is not burned onto the evaporation surface, and polymerized layers, formed especially during putting aside, due to drying up of oil, do not protect the film from heat transfer, as it occurs, if a heated vacuum evaporator with a film being wiped off is applied. As for the method according to the invention there is applied an unheated drop evaporator, and the distillation is realized from a thin dropping film, an expensive wiping off system is not necessary.
A time shortening of a high temperature influence upon oil is an important factor; in this way oil is prevented from oxidizing in a maximum extent. A removal of free fatty acids is nearly perfect, the achieved stage of neutralizing is about l/20 of the original content of free fatty acids in oil.
A physical neutralizing and deodorization of vegetable oil pursuant to the presented invention enables to produce oil with a high durability, biological and physiological value, as well as with sensoric properties of a high quality. Oil, treated in such a way, keeps its proper natural, biologically very important agents, such as tocopherols, phospholipides, natural antioxidants, phytosterols, vitamins, etc.
The mentioned process according to the invention, in comparison with other above mentioned processes of physical neutralizing and deodorization, does not require such high investment costs and operational ones. It does not require direct application of steam, the production of which requires much power. The applied vacuum is not so deep as in case of the patent SK 277 771, and said fact also spares investment costs and operational ones. The apparatus for performing the method according to the invention is more simple, cheaper and more reliable.

Examples

Examples which follows explain the invention:

Example l

Rape-seed oil gained by pressing (acidity No. O.95 mg KOH/g) is heated to 75 °C, and after adding O.9 wt. per cent of water it is hard mixed for twenty minutes. Subsequently there is added l wt. per cent of activated bleaching clay and it is hard mixed for further ten minutes. The gained suspension is filtered when hot. The colature is used as a spray in the heater where it is heated up to 210 °C. Oil, heated in this way, is supplied to an unheated short way drop vacuum heater, where it forms a thin dropping film in the evaporating space, and in this way a neutralizing and deodorization takes place. The oil supply is controlled so that the outlet temperature does not drop under 204 °C. Pressure in the evaporator was 250 Pa. The gained oil comprises O.OO5 per cent of water and its acidity number is O.O9 mg KOH/g.

Example 2

Sunflower oil, gained by pressing and extraction, with the acidity number 2.45 mg KOH/g, after having been settled and heated to 8O °C, was mixed with O.5 wt. per cent of water and after 20 minutes of mixing with O.6 wt per cent of bleaching clay. After l5 minutes of hard mixing, oil was finish filtered. Oil prepared in such a way was first preheated in in a preheater by means of outlet oil to l55 °C, and subsequently finish heated in the heater to l95 °C. Oil heated in such a way was neutralized and deodorized in an unheated short-way drop vacuum evaporator at a vacuum of 6OO Pa. Oil leaving the evaporator in the preheater (heat exchanger) preheats the supplied oil, and its temperature is decreased from l86 °C to 60 °C. Gained oil has a pleasant taste and odour of a sunflower; its acidity number is O.l8 mg KOH/g.

Example 3

Corn oil gained by pressing, having the acidity number 2.l mg KOH/g, was made free from mechanical impurities by means of filtration, and it is used directly as a spray into a preheater, where it is heated up to l7O °C. Oil heated in this way is supplied into a heater, it is heated up to the temperature of 220 °C, and then it is led into an evaporation space of an unheated short-way drop vacuum evaporator at the vacuum value of 5OO Pa. Gained oil is cooled down to 6O °C so that it hands over its heat to the entering oil. Gained oil has a pleasant taste and odour, and its acidity number is O.l25 mg KOH/g.

Industrial applicability

The method of neutralizing and deodorization of vegetable oils, designed above all for food purposes, on a physical principles pursuant to the presented invention may be applied especially for the production of edible oils, advantageously oils gained by pressing, suitable for applications in cold kitchen. Vegetable oils, especially rape-seed oil, sunflower one, corn oil and other ones, if refined in said way, without using chemicals, keep maximum quantity of their original natural agents, physiologicly very valuable, which advantageously affect and considerably prolong the oxidizing stability and sensoric one of oil refined in such a way.

Claims

A method of neutralizing and deodorization of filtered and/or settled raw and/or degummed and blanched vegetable oil, characterized in that vegetable oil heated to the temperature of l85 to 255 °C, is supplied to an unheated short-way drop vacuum evaporator, and the neutralizing and deodorization of oil is realized by means of a distillation of a thin film dropping down, at pressure of 2Ol to l OOO Pa and at the temperature of l8l to 250 °C.
The method as in Claim l, wherein vegetable oil is preheated in a preheater to the temperature of lOO to l70 °C and finish heated in a heater to the temperature of l85 to 255 °C.
The method as in Claim 2, wherein for preheating vegetable oil, there is used neutralized and deodorized vegetable oil leaving the evaporator.
The method as in any above Claim, wherein vegetable oil is oil for food purposes.
The method as in any above Claim, wherein vegetable oil is oil gained by pressing.