You can't mix utensils, and stuff like that. She said that in relation to dietary laws, kosher implies that there has been no involvement with forbidden animals such as shrimp, lobster and other shellfish, pork or products from a pig, or insects. Food processing equipment may handle non-kosher items, but then cannot be used for the handling of kosher foods. Even maple syrup needs to be carefully regulated because the custom was to throw a piece of fat or lard into the pot of boiling syrup to prevent it from boiling over. Kosher foods undergo a strict manufacturing process, which ensures that they are not contaminated with other products or machinery, which has been used to prepare non-kosher food products.
Produce is kosher by nature, as in the case of fruits and vegetables.
Acting as watchdog to make certain that kosher foods are truly kosher are hundreds of Jewish organizations that are not all considered reliable. Their symbols can be found on every product Rubin sells. I was able to track down Rabbi Nachman Levine with the Kosher Supervisors of Wisconsin at his home. Rabbi Levine goes into Rubin's home once a month to inspect the products she is sending out and certify that they are kosher. All of Rubin's products already have the certification symbol on them.