When sourcing rice and beans, quality is determined by physical characteristics and purity levels. For rice, focus on the broken grain percentage (e.g., 5%, 10%, or 25%), moisture content (ideally below 14%), and chalkiness. For beans, evaluate the uniformity of size, color consistency, and the absence of foreign matter (admixture < 0.5%). Always request a Certificate of Analysis (COA) and ensure the products meet Codex Alimentarius international food standards to guarantee safety and shelf-life stability.