Answer

Yes, generally you may use half a coconut today and keep the remaining half for tomorrow to make chutney during Paryushan, if it is stored properly and has not become stale, fermented, or spoiled.

Explanation

In Jain practice during Paryushan, extra care is taken regarding:

• Freshness of food
• Avoiding stale or fermented food
• Minimizing violence to tiny organisms
• Maintaining purity and discipline in eating

So if you cut a coconut today:

• Keep the remaining half clean and covered.
• Store it properly, preferably refrigerated if available.
• Use it the next day only if it is fresh, smells normal, and has not spoiled.
• If there is any doubt, it is better not to use it.

Spiritual Understanding

During Paryushan, the main spirit is carefulness, restraint, and purity. The goal is not only following food rules externally, but also practicing awareness and reducing harm as much as possible.

Takeaway

You can use the remaining coconut tomorrow if it remains fresh and pure. If there is any doubt about spoilage, avoid using it during Paryushan.