35. Sample checking. Sometimes, the insect lab departments of kashrus agencies perform an inspection of a sample to see whether the food is infested. This only helps for an insignificant minority or to determine whether something is, in fact, a significant minority or not. Sometimes there are different levels of infestation in varieties of foods depending on the season—sometimes it is an insignificant minority, and sometimes it is a significant minority. In that case, one can rely on checking a sample to determine its classification.
36. Similarly, if there is a type of produce assumed to be free of bugs, but there is a concern of infestation for some reason, e.g., it was stored for a prolonged time, one may rely on checking a sample to ensure it did not become infested (תשב''ץ ח''ג סי' י''א ).
37. Doesn’t help. However, if there is a significant minority requiring one to check mid’rabanan, checking a sample does not help. Even checking the majority of the produce does not help; one must check each and every item (רמ''א סי' פ''ד סוף ס''ח ).
