यातयामं गतरसं पूति पर्युषितं च यत् ।
उच्छिष्टमपि चामेध्यं भोजनं तामसप्रियम् ॥ १७.१० ॥

yāta-yāmaṁ gata-rasaṁ pūti paryuṣitaṁ ca yat |
ucchiṣṭam-api cāmedhyaṁ bhojanaṁ tāmasa-priyam || 17.10 ||

Tāmasika food consists of items which are left over after eating, stale, tasteless, insipid, putrid, polluted and the like.

To categorize food like this into three kinds, dwelling mainly upon the sāttvika features is a great contribution to the science of food and nourishment. The effort of the seeker must be to get tuned to sāttvika food, using minimum of condiments, spices, and such other additives.