I am S.Waseem, engaged in selling carrageenan in Russia, thus, it is extremely important for me to select a reliable supplier of carrageenan.
Certificate
A formal operation supplier of food additives normally passes ISO certificate as well as other well-known certificate like halal, kosher, ect.
Supply of Products
Compared with Manufacturers, other than service advantage, main advantage of trading companies lies in being able to provide various kinds of products. For example, when we would like to order carrageenan as well as several other food ingredients, trading companies becomes the best choice, since unlike factories, traders can provide one-stop service and have greater bargaining powder which permits a lower price.
Of course , we can purchase carrageenan directly from manufacturers if the volume is large enough, but it won’t be a bad choice if we keep in touch with some large-scaled traders. Because once your long-term-cooperate factory is in short of carrageenan , we can turn to trading companies, who can help to find other suppliers shortly or even direct supply carrageenan in no time.
As far as we know, big suppliers of food additives and ingredients can basically provide more than 100 kinds of products, among which, Foodchem International Corporation are able to supply overseas customers more than 300 kinds of food additives and ingredients, plant extracts, nutritional supplements, apis, etc.
Google “Company Name”
A renowned company name usually shows a great deal results on Goolge Search, because its company name is frequently searched by their customers or cited by other web sites.
Take “Foodchem International Corporation” as an example, as has been showed in the below picture, there comes out more than 298,000 searching results on Google. 
Sales of Supplier
There are tons of suppliers of carrageenan in China, thus, supply scale should be important, carrageenan suppliers with a certain size suppliers tend to have more bargaining power, in some country, we can even find their carrageenan supply volumes through customs data.
Company Name
As a professional trader or manufacturer of food additives, normally its company name has food, chemical, additives or other key words in it. Other trading companies who have affairs in all fields, usually performs unprofessionally.
Size of Team
Member Size of suppliers or manufacturers also plays a very important role; generally number of manufacturers is slightly larger than traders. A complete overseas trade involves a lot of sessions; To perform perfectly, each session requires well-professional persons. A well-founded overseas trading company generally includes online marketing, sales, logistics, purchasing, service, administration departments, etc.
Normally we can scan through the vendor’s web site or some third-party social networking sites to confirm suppliers’ team size.
Shipping and Payment
In order to meets different needs of buyers, according to intercoms, carrageenan suppliers often provides several payment ways, such as FOB, L/C, D/P, T/T and so on.
Exquisite Website
Qualified carrageenan suppliers tend to have more elaborate and professional web site, with better user experiences and less bugs or faults.
http://fr.foodadditives.com/prot%C3%A9ines/Pea-concentr%C3%A9s-de-prot%C3%A9ines.html