In the processing of which crop does Gujarat enjoy a monopoly, as stated in the review?

1. The horticulture section lists Gujarat's specialised processing strengths. 2. The state enjoys a monopoly in the processing of Isabgul. 3. Its onion dehydration industry is the biggest in the country, but that is a different product. 4. Therefore Gujarat has a monopoly in processing Isabgul. _Source: Socio-Economic Review 2019-20, Gujarat State (Directorate of Economics & Statistics), p.25_