Alot of people have recommended Grapeseed Extract Grapefruit-Seed-Extract and I k now from my dealings with natural cosmetics that this is not a preservative that works as the cosmetics go mouldy so it would suggest that it stands no chance as an anti-fungal to kill Candida. The same could be said of Aloe Vera juice.
Options worth trying in my mid would be the proven anti bacterials/Anti fungals : Lemon juice, Vinegar, Preserved Vegetables, Salt, Vitamin C etc