Astanga Hrudaya
पट्वम्लमधुराः स्निग्धाः सृष्टविण्मूत्रमारुताः। पटोः कषायस्तस्माच्च मधुरः परमं गुरुः॥३८॥
Snigdha- while Patu (salt), Amla (sour), Madhura (sweet) are unctuous and help elimination of faeces, urine and flatus, each one more so in their succeeding order. Guru- Patu (salt), Kashaya (astringent) and Madhura (sweet) are heavy to digest, each one more so in their succeeding order.
english translation