as used in Section 52451, Food and Agricultural Code, means cleaning, scarifying, or blending to obtain uniform quality, and other operations which would change the purity or germination of the seed and therefore require retesting to determine the quality of the seed; but not to include operations such as packaging, labeling, blending together of uniform lots of the same kind or variety without cleaning, or the preparation of a mixture without cleaning, any of which would not require retesting to determine the quality of the seed.