spoilage vs souring

spoilage and souring both are nouns.

Word	Noun	Adjective	Verb	Adverb
spoilage	Yes	No	No	No
souring	Yes	No	No	No

As nouns, souring is a hyponym of spoilage; that is, souring is a word with a more specific, narrower meaning than spoilage:

Other hyponyms of spoilage include mildew, mold, mould.

spoilage (noun)	souring (noun)
the act of spoiling something by causing damage to it	the process of becoming sour
the process of becoming spoiled
the amount that has spoiled