Seeds purity standards

All herbage seed production in the UK is overseen by FERA and NIAB. Only Basic seed is used for Cl generation production (termed CS). In some cases it is permitted for seed crops to be taken from the same crop for two seasons, but no C2 generation multiplication is pernritted. All seed crops are inspected at around the time of ear emergence to estabUsh variety type and to check for off-types, weeds and isolation. Standards for varietal purity are quite high and in the case of Basic seed only one off-type is allowed per 30 square metres. In the case of CS seed the standard is one per 10 square metres. 

The simplest and cheapest procedure to obtain standards is based on selective extraction followed by crystallization. A method developed to obtain lycopene from tomato residue using factorial experimental design consisted of a preliminary water removal with ethanol, followed by extraction with EtOAc and two successive crys-talhzation processes using dichloromethane and ethanol (1 4), producing lycopene crystals with 98% purity, measured by HPLC-PDA. Using this approach, bixin was extracted with EtOAc from annatto seeds that were previously washed with... 

While, this paper purposefully foeused on 5-HTP, other compounds are of interest and natural Griffonia seeds are also known to 4-indole-3-aeetyl-aspartic aeid (lAAA) and 5-hydroxyindole-3-acetie aeid (5-HlAA). In addition, the GSB reeognizes the importance of the fatty acid profile of the seeds, and that changes in the fatly aeids will reflect seed and oil age, quality and purity. As such, rountine measurements of both free fatly aeids and the peroxide value of the Griflbiua seed oil are recommended to be tested and included in grades and standards. 

The minimum standard at which certified cereal seed can be marketed is 99% analytical purity (99.7% for Cl and 99.9% for Cl HVS), 85% germination (80% for triticale and 75% for naked oats) and a maximum of 17% moisture content. There are also specific standards for the content of wild oats and eigot pieces and also seeds of com cockle, couch, sterile brome and wild radish. 

Certified, Pre-Basic and Basic seeds of oilseed and turnip rape have a minimum analytical purity of 98% and a minimum germination of 85%. The maximum content by weight of other seed species is 0.3%. There are also specific standards applied for wild oats, dodder, dock, wild radish, black-grass and flaxfield ryegrass contamination. 

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