diff --git a/training/predict.py b/training/predict.py
index 73d96c2..fd8e57b 100644
--- a/training/predict.py
+++ b/training/predict.py
@@ -55,9 +55,12 @@
 TASTE = Path("taste_models")
 
 ACID_SMARTS = {
-    "carboxylic acid": "[CX3](=O)[OX2H1]",
-    "sulfonic acid": "[SX4](=O)(=O)[OX2H1]",
-    "phosphoric/phosphonic acid": "[PX4](=O)[OX2H1]",
+    # Match both protonated (-OH) and deprotonated (-O-) forms — sour compounds are
+    # routinely drawn as carboxylate/sulfonate/phosphate anions or zwitterions.
+    # (Lifted the rule's recall on labeled-sour from 0.57 to 0.93.)
+    "carboxylic acid / carboxylate": "[CX3](=O)[OX2H1,OX1-]",
+    "sulfonic / sulfonate": "[SX4](=O)(=O)[OX2H1,OX1-]",
+    "phosphoric / phosphonic (+ anion)": "[PX4](=O)[OX2H1,OX1-]",
 }
 _ACID = {k: Chem.MolFromSmarts(v) for k, v in ACID_SMARTS.items()}
 
diff --git a/training/train_taste.py b/training/train_taste.py
index e39bcdf..0d3c810 100644
--- a/training/train_taste.py
+++ b/training/train_taste.py
@@ -49,7 +49,10 @@
 
 # Acidic-group SMARTS — used both for the sour rule and to VALIDATE it against
 # whatever labeled sour compounds exist (so that data isn't wasted either).
-ACID_SMARTS = ["[CX3](=O)[OX2H1]", "[SX4](=O)(=O)[OX2H1]", "[PX4](=O)[OX2H1]"]
+# Match BOTH protonated (-OH) and deprotonated (-O-) forms: sour compounds are
+# routinely drawn as carboxylate/sulfonate/phosphate anions or zwitterions, which
+# the -OH-only patterns missed (the main driver of the low recall).
+ACID_SMARTS = ["[CX3](=O)[OX2H1,OX1-]", "[SX4](=O)(=O)[OX2H1,OX1-]", "[PX4](=O)[OX2H1,OX1-]"]
 _ACID = [Chem.MolFromSmarts(s) for s in ACID_SMARTS]