• Energy Research

Pineapple is a fruit of unique appearance and flavor, consumed in natura or processed to obtain different products. However, the processing step generates a series of residues such as crown, stem, cylinder, leaves, and pomace, which have been widely studied due to the high amount of bioactive compounds, dietary fibers, and commercial enzymes found. Different government institutions already established laws detailing treatments required for fruits, like pineapple, and other food waste, either for reuse or disposal. Public policies and waste reuse are necessary to achieve sustainable development, expanding the possibilities for discovering new products and compounds. The current review analyzed different propositions from the literature on the application and valorization of pineapple waste, besides presenting industrial applications for these residues and legislative aspects related to residue treatment policies of different governmental institutions.

Biosurfactants have attracted considerable attention because of their lower toxicity, biocompatibility, and effectiveness over chemical surfactants. The use of renewable sources and the concept of sustainable production for such biomolecules supports the increased demand for eco-friendly products. Herein, the present study investigated corncobs (CC) and sunflower stalks (SS) as substitutes for conventional substrates in submerged fermentation with B. subtilis. The agro-industrial residues were submitted to an alkaline pretreatment to obtain hydrolysates rich in hemicelluloses, whose concentrations were determined at 48.8% and 65.7% for corncob and sunflower stalk liquors, respectively. The influence of different concentrations of glucose (0, 2.5, and 5%) and liquor (0, 20%, and 40%) were evaluated according to cell concentration, surface tension reduction rate (STRR), and emulsification index (EI24). Biosurfactants obtained with the hemicellulose liquor of sunflower stalk showed the highest cell concentration (4.57 g/L) and STRR (58.07%), whereas the maximum values of EI24 (56.90% in hexane, 65.63% in toluene, and 64.86% in kerosene) were achieved by using corncob liquor. All top results were observed at 2.5% glucose, 20% liquor (CC or SS), and 1% mineral salts. Notably, excess glucose or liquor (CC or SS) negatively affected cell growth and biosurfactant performance. The results indicated the potential of corncobs and sunflower stalks as low-cost substrates to produce a high added-value biosurfactant with promising tensoative and emulsifying properties.