Bamboo Leaves – characterization and potential applications

Bamboo’s culms have many uses in Brazil, however, bamboo leaves (BLV) are responsible for 190k tonnes/year of agricultural waste, despite its high antioxidant and nutritious profile. Aiming to promote the complete use of bamboo, we characterized the leaves of Bambusa tuldoides (BT), Dendrocalamus asper (DA), Phyllostachys edulis (PE) and Phyllostachis nigra (PN), collected in IAC/APTA (Tatuí/SP; lat: -23.3556, long: -47.8569 WGS84). Images were taken from the fresh leaves using a digital scanner and a portable microscope. The influence of drying temperatures (40/50/60ºC) on BLV’s phenolic content was determined. Dried and milled leaves (30 mesh) were characterized by their proximate and mineral composition (spectrometer), silica content (by difference, ashes-minerals), and phenolic content (Folin-Ciocalteu), data was evaluated by t-test (p<0.05). The antimicrobial activity of BLV ethanolic extract was assessed by minimal inhibitory concentration (M07-CLSI) analysis at CPQBA (Paulínia-SP). Drying at 60ºC/70-100 minutes achieved the best results, e.g. BT moisture went from 38.92±0.07% to 3.87±0.34% and total phenolics from 12,85±0,11 to 10,09±0,04 mg gallic acid/100g. BLV protein content ranged from 12.23±0.49% to 15.16±0.33% (BT,DA); lipids from 3.40±0.12% to 5.12±0.34% (PN,DA); ashes from 9.15±1.24% to 9.15±1.24 (PE,BT); and carbohydrates, comprising fibres, starches and sugars, from 29.48 to 41.85 (BT,DA). Furthermore, they contain high amounts of potassium (0.49±0.04% to 1.70±0.07% (BT,PE)), calcium (0.32±0.01% to 0.92±0.06% (PE,BT)), magnesium (0.14±0.09% to 0.30±0.01% g/kg (PN,DA)), and a silica calculated content of 6,91% to 14.14% (PE,BT), with significant differences between species. BLV showed no antimicrobial activity against: Lactobacillus brevis, Pediococcus damnosus, acetic bacteria, Brettanomyces bruxelensis, Bacillus cereus, or Saccharomyces cereviseae, only DA showed bactericide effects over P. damnosus at 12.5 mg/ml. Overall, BLV exhibited attractive characteristics for use as an ingredient in the food and beverage industry, e.g. in the brewing process, where its high protein, mineral and silica content could bring desirable effects on foam and beer clarification.