Edible Fat and Oil Processing

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Introduction

There are a number of suppliers of oil and fat products used for edible purposes. These products include, but are not limited to olive oil, peanut oil, soybean oil, sunflower oil, lard, shortening, butter, and margarine. The raw materials for these products include animal by-products, fleshy fruits (palm and olive), and oilseeds. The crude fats and oils from these sources are recovered using a number of methods such as rendering, pressing and extracting with solvents. Some oils, such as virgin olive oil, are ready for consumption after this initial step (pressing), while other requires additional processing. The extent of fat and oil processing depends on the source, quality, and nature of the end use.

Alkali Refining

The growing demand, in the United States especially, for bland-tasting, stable oils and shortenings for the end user has driven the development of extensive processing techniques. The constituents of crude fats and oils that contribute to unwanted flavor and color are free fatty acids, waxes, color pigments, phospholipids (gums), oxidized products, metal ions, and carotenoids. Many of these undesirables can be removed by Alkali refining. Alkali refining is the removal of these unwanted items by a chemical reaction with an alkali (caustic soda). This process is completed by a four step process: Conditioning, Neutralization, Washing, and Drying. The fats are heated between 40o and 85oC and treated with an aqueous solution of sodium hydroxide or sodium carbonate. Conditioning transforms non-hydrate phospholipids into their hydrate form by breaking down metal/phosphatide complexes with a strong acid. In neutralization the removal of free fatty acids and residual gums takes place. Washing is the removal of residual gums by hot water. And drying is the removal of moisture under a vacuum.

Inductive Conductivity can be used to provide a continuous, on-line indication of the aqueous Alkali solution concentration. The aqueous emulsion formed by the impurities is drawn off the bottom of the tank (in batch refining) or centrifuged off (in continuous refining). After alkali refining, the oil is usually washed with water to remove any residual alkali or emulsion. Measuring the conductivity of this wash water can indicate its quality. Clean water with low dissolved solids will exhibit low conductivity.

Inductive Conductivity

Water Refining

Also known as degumming, water refining consists of treating the crude oil with a small amount of water. "Degumming" is where phosphotites in the Oil are hydrated with water and then removed by separating in the Centrifugal Separators. The Degummed Oil is then subject to neutralization with caustic soda where the free fatty acids are converted into residual gums and are separated in hermetic separators. The neutralized oil is then washed and dried.

The "gummy" emulsion of phospholipids created by the treatment with water is then centrifuged off. In the case of corn and soybean oil, this emulsion can be dried to produce a substance known as lecithin, which is used as a emulsifier in many applications. Because of this, the water used in the degumming process needs to be of high quality. Any impurities in the water will end up in the product after the drying process. Once again, conductivity can provide a low maintenance indication of water quality.

Deodorization

Most fats, even after refining, have characteristic flavors and odors, and vegetable fats especially have a relatively strong taste that is foreign to that of butter and are considered undesirable. In order to produce a tasteless, butter-like fat, these oils may undergo deodorization. To do so steam is blown through the heated oil to distill the volatile components responsible for these flavors and odors. Of course, in order to generate steam you will need water, clean water. pH and conductivity measurements of the feed water are mandatory in this process to ensure the protection of the process equipment from corrosion and scaling. Other than water, you need heat to generate the steam. Proper control of excess oxygen in flue gas allows the boiler to be operated efficiently and safely.

Hydrogenation

For many purposes, it is desirable for the oil to be solid, or semi-solid (margarine and shortenings). The process that converts liquid oils to higher-melting solids is called hydrogenation. The process consists of dispersing hydrogen atoms to double bonds of a molecule through heated oil in the presences of a catalyst¹. Cylinders from a vendor may supply the hydrogen, but some plants produce it on-site. This usually involves the electrolysis² of water to form oxygen and hydrogen. It is critical for the water used in the process to be pure. Contacting conductivity can be used to ensure the quality of the water in order to prevent damage to the expensive equipment used to generate the hydrogen. The purity of the hydrogen used in this process is critical, both for the product quality, and the process efficiency. Gas Density can be used to measure the purity of the hydrogen gas leaving the generation system.

Notes

  1. A catalyst is a substance which speeds up a reaction, but is chemically unchanged at the end of the reaction.
  2. Electrolysis is a method of separating chemically bonded elements and compounds by passing an electric current through them.

Summary

There are many points in the processing of edible fats and oils that benefit from the use of analytical measurements. Inductive Conductivity, Contacting Conductivity, Gas Density and pH can be utilized to increase the quality of the end product, as well as protecting expensive process

Product Recommendations

Yokogawa SC4A and the SC42 series

Sensors:

For measurements of low conductivity, contacting sensors are recommended such as the Yokogawa SC4A and the SC42 series. For cleaning and rinse processes, inductive conductivity offers the best solutions with a minimum of maintenance.

For pH measurements the FU24 All-in-One pH/ORP sensor is the best solution. By incorporating the successful Yokogawa patented Bellow system integrated in the FU24 electrode, the built-in bellows ensures immediate interior pressure equalization to the outside pressure, making the sensor virtually insensitive to external pressure variations and potential plugging.

EXAxt450

Holders:

All of Yokogawa sensors can be installed online, retractable, or flow-thru, depending on which installation the customer requirements. Material construction for Yokogawa sensors and holder may vary, but typically is 316SS.

Analyzers:

The Yokogawa model EXAxt450 analyzers should be used for applications where 115 VAC equipment is required, The Yokogawa Model FLXA21 analyzer should be used for application where 24 VDC loop powered equipment is required.

Related Products & Solutions

2-Wire Transmitter/Analyzer FLXA202/21

The FLEXA™ series analyzers are used for continuous on-line measurements in industrial installations. With an option for single or dual sensor measurement, they are the most flexible two-wire analyzer available.

4-Wire pH/ORP Analyzer PH450

The PH450 pH and ORP analyzer is a multivariable analyzer that combines pH with temperature and ORP (Redox) measurement, which can be utilized through different output functions: two mA current outputs, four independent SPDT contact outputs and HART. 

All-in-One Digital Smart pH/ORP Sensor FU20F

All-In-One pH and ORP digital SMART sensor that keeps the motto "Simple is best" while combing the sensor with built-in intelligence and direct digital communication. 

All-in-One Digital SMART pH/ORP Sensor FU24F

The FU24F is a digital SMART pH/ORP sensor made with a chemical resistant PPS 40GF body for harsh pH applications.

All-in-One pH/ORP Sensor Series FU20/FU24/PH20

The PH20, FU20 and FU24, all-in-one pH and ORP, sensors show how Yokogawa applies the motto "Simple is best" to sensor technology.

Contacting Conductivity Sensors SC42/SC4A(J)

The measurement of specific conductivity in aqueous solutions is becoming increasingly important for the determination of impurities in water.  Yokogawa has designed a full range of precision sensors and instruments to cope with these measurements, even under extreme conditions.

GD40 Detector

The GD40 detector is designed for intrinsically safe and flameproof, explosion protected applications. It is designed to be virtually maintenance free for all accepted applications.

GD402 Analyzer

The Model GD402 gas density analyzer and Model GD40 detector not only provide continuous measurement of gas density, but also several other valuable parameters, including specific gravity and molecular weight. The Model GD402 is a rugged microprocessor-based converter designed in two versions to meet both general area and explosion-proof application requirements.

Pure Water (Low) Conductivity sensors SC4A(J)/SC42

Intended for the low conductivity applications found in the semi-conductor, power, water and pharmaceutical industries, these sensors are in a convenient compact style.

SENCOM PC Software

The SENCOM PC Software, SPS24, offers a unique means to optimize the performance of pH/ORP sensors for enhanced reliability and process safety. The software allows the operator to monitor pH/ORP sensor performance, calibrate and configure various parameters.

 

Gas Density/Hydrogen Purity Analyzer

Gas Density detectors and analyzers provide continuous measurement of gas density; as well as, several other valuable paramenters, including specific gravity and molecular weight.

pH and ORP Analyzers

pH and ORP meters, analyzers and transmitters are used for continuous process monitoring of pH and ORP to ensure water/product quality, monitor effluent discharge, batch neutralization, pulp stock, scrubbers, cooling towers, chemical, water/wastewater treatment and many other applications.

pH and ORP Sensors

pH electrodes and sensors are the sensing portions of a pH measurement. Various installation options including retractable, flow thru, immersion, and direct insertion. Proper pH electrode/sensor selection is critical for optimal measurement results.

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