The first and most intuitive standard to judge premium walnut kernels at exhibitions is appearance and color. High-quality natural walnut kernels feature a uniform extra light or light creamy yellow hue, with smooth and full surfaces, no dark spots, discoloration, or shriveled textures. Dark brown or unevenly colored kernels usually indicate over-storage, oxidation, or improper drying, which leads to bitter tastes and reduced nutritional value. Buyers should prioritize whole half-kernels with complete shapes and minimal broken pieces, as intact walnut kernels guarantee better market sales and longer shelf life for retail and food processing use.

Professional buyers must also focus on product purity and food safety certification, which determines whether walnut kernels meet national import requirements. Reliable exhibition suppliers provide kernels with strict impurity removal, free of shell residues, dust, mold, and foreign matter. Formal export-grade walnut kernels must hold authoritative certifications including HACCP, HALAL, and BRC, fully complying with European, Middle Eastern, and Southeast Asian import inspection standards. Avoid uncertified bulk walnut kernels, as they face high risks of customs detention and sales restrictions.