The amount of enzyme required for complete digestion depends on the substrate's structure, purity, and quantity. Modifications such as branching or fucosylation can reduce or inhibit enzymatic cleavage, and oligosaccharides in the neolacto-group may be cleaved at significantly reduced rates.
To address incomplete digestion, you can extend the incubation time, increase the enzyme concentration, or apply a combination of both. However, incubation beyond 8 hours at 37°C is unlikely to result in significant improvement.