Short answer. It depends on whether the things were appraised at the start. If they were appraised when delivered, the usufructuary must pay that appraised value when the usufruct ends. If not appraised, the usufructuary may return the same quantity and quality, or pay their current market price.
What the law says
Whenever the usufruct includes things which cannot be used without being consumed, the usufructuary shall have the right to make use of them under the obligation of paying their appraised value at the termination of the usufruct, if they were appraised when delivered. In case they were not appraised, he shall have the right to return the same quantity and quality, or pay their current price at the time the usufruct ceases.
Civil Code, Article 574 — Usufruct Over Things That Are Consumed by Use. Read the full provision →
Consumable things and the usufruct problem
Ordinary usufruct returns the same thing it borrowed — you use a property and then restore it. But some things can only be used by consuming them: food, fuel, raw materials. You cannot return what no longer exists. Article 574 of the Civil Code addresses this through a modified usufruct — sometimes called a quasi-usufruct — that gives the usufructuary permission to consume the items while requiring a substitute to be returned when the usufruct ends. What exactly must be returned depends on whether the items were appraised at the beginning.
When an appraisal was made at delivery
If the consumable things were appraised when they were delivered to the usufructuary, the rule is straightforward: at the end of the usufruct, the usufructuary must pay their appraised value. The value was fixed at delivery, so the obligation is a definite monetary amount. The owner knows what they had; the usufructuary knows what they owe. This clean accounting makes the appraisal at delivery very useful — it locks in the number and removes uncertainty about what current prices might look like when the usufruct finally ends.
When no appraisal was made
If the consumable items were not appraised when delivered, the usufructuary has a choice. They may either return the same quantity and quality of the items — the same amount of the same type of goods — or they may pay the current price at the time the usufruct ceases. The first option works well when the items are fungible and the market for them is stable. The second becomes relevant when returning the same kind of goods is difficult or when prices have changed. The option belongs to the usufructuary, not the owner.
Why the appraisal matters so much
The difference between an appraised and an unapprised delivery is significant in practice. If prices rise sharply between delivery and the end of the usufruct, and no appraisal was made, the owner benefits — the current-price option gives them higher compensation. If prices fall, the usufructuary may prefer to pay current price rather than deliver the same quantity. If there was an appraisal, none of this uncertainty exists — the value is fixed. For both the usufructuary and the owner, getting a proper appraisal at the start of a usufruct covering consumable things is protective, not just procedural.