Study of vacuum drying on guava (Psidium guajava) Bambang Susilo (a*), Sumardi(a), Abd. Rohim(b), Rizki Putra Samudra(a), Michael Manalu(a) and Midia Lestari Wahyu Handayani(c)
a) Department of Biosystem Engineering, Faculty of Agricultural Technology, Universitas Brawijaya, Veteran Street, Malang 65145, Indonesia
b) Doctoral Program of Food Science, Faculty of Agricultural Technology, Universitas Brawijaya, Veteran Street, Malang 65145, Indonesia
c) Central Laboratory of Life Sciences, Universitas Brawijaya, Veteran Street, Malang 65145, Indonesia
*susilo[at]ub.ac.id
Abstract
Psidium guajava is the most widely guava species cultivated in Indonesia for food consumption delight, even as fresh, juice and beverages. Guava fruit harvesting at the optimal ripeness stage possesses rich vitamin C and antioxidant constituents. Proper post-harvest handling plays an important role in its processing, nutritional content, and physicochemical characteristic, in order to preserve decay and farmer-economically loss. Currently experiment, a water jet vacuum dryer system was employed for post-harvest guava drying, complementary with a double jacket system and waste cooking oil insulator. The impact of different temperatures and pressures (40^{o} C, 50^{o} C, and 60^{o} C- -69 cmHg and -35 cmHg successively) on mass reduction, moisture, vitamin C, color, and hardness were studied for guava slices drying. The result, 60^{o} C -35 cmHg was the best in moisture reduction (9.26 \pm 0.43 %), mass subtraction (34.43 \pm 0.16 g), and color quality, as well as the most hardness (1.18 \pm 0.13 kgf) for 10 h drying. Meanwhile, the vitamin C content is still undergoing analysis. Vacuum drying of guava could produce dried guava slices in good quantity and quality, within a concise drying time.
