Possibilities of valorization of Gnetum spp leaves in modern gastronomy: Production and characterization of new vegetable tarts and salads

Gnetum spp is a green creeper plant abundantly found in the Central African forests. Their leaves are eaten as vegetable by inhabitants. In order to valorize this vegetable in modern gastronomy, a survey was carried out in three towns of Cameroon to evaluate its importance in the feeding habits. The leaves were also sliced in two different forms, precooked, spin-dried and used for Gnetum tarts and salads production. 50, 100 and 150 g of thin sliced precooked leaves were used to prepare three salads and three tarts, keeping the other ingredients constant. Three additional tarts were prepared similarly using thinnest sliced precooked leaves. The final products were analyzed in terms of physiochemical, nutritional and sensorial properties. More than 96.9% of people investigated eat Gnetum leafy vegetables at least once per month. The survey study indicates that the transformation of Gnetum is mostly done by people within the age of 20 to 40 years old. Results of the physicochemical analyses showed that the total protein, lipid and carbohydrate contents increased in general with the increasing of the Gnetum leaf quantities used for preparation. The crude fiber contents of salads and tarts ranged from 52.00 ± 0.68 to 62.66 ± 1.26 and 29.33 ± 0.67 to 33.66 ± 0.47 g/100 g DW respectively. They were positively correlated with the quantity of Gnetum leaves used. The total phenolic contents, also increased significantly (p < 0.05) with the quantity of Gnetum leaves, from 182.45 ± 1.69 to 493.52 ± 2.10 mg/100 g DW for the salad and from 86.69 ± 4.08 to 283.21 ± 6.79 mg/100 g DW for the tart. The calculated energy density of tarts and salads permitted to classify these food products as low and high energy density foods respectively. The nutritional densities of produced tarts oscillated from 0.27 to 0.3 and that of salads from 0.58 to 0.71. With their nutritional values and the significant amount of fibers, Gnetum tarts and salads could be good new recipes to valorize the Gnetum leafy vegetables.