Maize (Zea mays L.) is a grass native to North America (the United States is the largest producer in the world). It is an annual plant. The caryopsis contains about 5% of oil of which 80% is concentrated in the germ. To extract the oil, the germ is isolated from the rest of the seed by means of wet grinding. Corn germ oil is extracted by means of solvents. The crude oil has a red-amber color and has a high content of phosphatides and traces of waxes. It is used as a table oil and is considered one of the most valuable seed oils as it has a remarkable stability to oxidation. According to the regulations in force, the oil must meet the requirements indicated in the following technical data sheet:
| CARATTERISTICA | REQUISITI | METODO DI ANALISI | |
|---|---|---|---|
| Relative density at a 20/20°C | from 0,917 to 0,925 | See A.1.1 | |
| Refractive index nD at 40°C | from 1,465 to 1,468 | See A.1.2 | |
| Number of iodine | from 103 to 135 | See A.1.3 | |
| Content in sterols mg / kg | from 5000 to 22100 | See A.1.5 | |
| Acidity, expressed as oleic acid,% | max 0,5 | See A.1.6 | |
| Number of peroxides, meq oxygen / kg | max 7,0 | See A.1.7 | |
| Impurities (petroleum ether)% | max 0,05 | UNI EN ISO 663 | |
| Soaps, expressed as sodium oleate, mg / kg | max 10 | See A.1.8 | |
| Metals, mg / kg (**) | |||
| iron | max 1,5 | UNI EN ISO 8294 | |
| copper | max 0,1 | UNI EN ISO 8294 | |
| lead (1) | max 0,1 | UNI EN ISO 12193 | |
| arsenic | max 0,1 | See A.2.1 | |
| Solvents, mg / kg (***) | |||
| hexane | max 1 | ||
| CARATTERI ORGANOLETTICI | |||
| smell and taste | Delicate flavor characteristic of the oil, free from anomalous or unpleasant odors or tastes | ||
| appearance | clear 20°C | ||
| color | the spectrophotometric absorptions, measured on diluted oil with the same volume of hexane, in a 1 cm tray, with reference to normal hexane, must not exceed the values of 0.20 and 0.10 respectively at 420 and 453 nm | ||
| Permitted additives and relative limits | According to current legislation (2) | ||
| Aromatic polycyclic hydrocardides | According to CE 333/07 and subsequent amendments | ||
| Composition of fatty acids, GLC (capillary),% ISO 5508 | Composition of sterols, GLC (capillary),% See A.1.4 | ||
| CHARACTERISTIC | REQUIREMENTS | CHARACTERISTIC | REQUIREMENTS |
| C12:0 - Lauric Acid | ND - 0,1 | Cholesterol | from 0,2 to 0,6 |
| C14:0 - Myristic acid | ND - 0,1 | Brassicasterolo | ND - 0,2 |
| C16:0 - Palmitic acid | from 8,6 to 14,0 | 24-Methylene cholesterol | § |
| C16:1 - Palmitoleic acid * | ND - 0,5 | Campesterol | from 16,0 to 24,1 |
| C17:0 - Heptadecenoic acid | ND - 0,1 | Campestanol | § |
| C17:1 - Heptadecenoic acid | ND - 0,1 | Stigmasterolo | 4,3 to 8,0 |
| C18:0 - Stearic acid | ND - 3,3 | Delta 7 - Campesterol | § |
| C18:1 - Oleic acid * | from 20,0 to 42,2 | Delta 5.23 - Stigmastadienol | § |
| C18:2 - Linoleic acid | from 34,0 to 65,6 | Clerosterol | § |
| C18:3 - Linoleic acid | ND - 1,2 | Beta - sitosterol | from 54,8 to 66,6 |
| C20:0 - Arachic acid | from 0,3 to 1,0 | Sitostanol | § |
| C20:1 - Eicosenoic acid | from 0,2 to 0,6 | Delta5 - Avenasterolo | from 1,5 to 8,2 |
| C20:2 - Eicosadienoic acid | ND - 0,1 | Delta 7.9 (0.11) - Stigmastadienol | § |
| C22:0 - Behenic acid | ND - 0,2 | Delta 5.24 - Stigmastadienol | § |
| C22:1 - Erucic acid | ND | Delta 7 - Stigmastenol | from 0,2 to 1,0 |
| C22:2 - Docosadienoic acid | ND | Delta7 - Avenasterol | from 0,3 to 1,2 |
| C24:0 - Lignoceric acid | ND - 0,3 | ||
| C24 :1 - Tetracosenoic acid | ND |
* Sum of positional isomers which may or may not be separated under the test conditions
** Codex Alimentarius
*** Law Decree n. 64/1993
(1) EC Regulation 466 of 08/03/2001
(2) At the date of publication of this standard, the D.M. n. 209 – 27.2.1996, (Official Gazette no. 96 – 24.4.1996)
§ The components indicated with § and for which no limit value has been set must not be taken into consideration for the purity assessment.
NORMATIVE REQUIREMENTS
ISO 5508 – Animal and Vegetable fats and oils – Analysis by gaschromatografy of methilesthers of fatty acids
ISO 5509 – Animal and Vegetable fats and oils – Preparation of methyl esters of fatty acids
UNI EN ISO 663 – Vegetable and animal oils and fats – Determination of the content of insoluble impurities
UNI EN ISO 8294 – vegetable and animal oils and fats – Determination of the content of copper, iron and nickel. Method for atomic absorption spectrometry with a graphite furnace.
UNI EN ISO 12193 – Vegetable and animal oils and fats – Determination of lead content. Method for atomic absorption spectrometry with a graphite furnace.
APPENDIX (information)
A BIBLIOGRAPHY
A.1 NGD REFERENCE METHODS (GRASS STANDARDS AND DERIVATIVES)
A.1.1 NGD C18- Determination of the relative density
A.1.2 NGD C31 – Determination of the refractive index
A.1.3 NGD C32- Determination of the iodine number according to Wijs
A.1.4 NGD C71 – Determination of sterol composition by capillary column gas chromatography
A.1.5 NGD C72 – Determination of sterol content by capillary column gas chromatography
A.1.6 NGD C10 – Determination of acidity
A.1.7 NGD C35 – Determination of the number of peroxides
A.1.8 NGD C8 – Determination of soaps
A.2 OTHER REFERENCE METHODS
A.2.1 AOAC 963.21 – 1990 Arsenic in food. Kjeldahl Flask Digestion. Final action.
AOAC 952.13- 1990 Arsenic in food. Silver Diethyldithiocarbamate method. Final action.