Compositional analysis (qualitative and quantitative) of pineapple by-products extracts ? stablishing the relationship between composition and bioactivity

DÉBORA A. CAMPOS; LORENZO M. PASTRANA-CASTRO; JOSÉ A. TEIXEIRA; EZEQUIEL R. COSCUETA; MANUELA E. PINTADO

Aveiro

Congreso; 12ª Reunião do Grupo de Glúcidos (GLUPOR12); 2017

Pineapple (Ananas comosus) is the third most important tropical fruit in the world production and one of the most processed fruit in industry, but is one of the most important creating residues. Thus, in the agro-food sector, several materials are eliminated as waste throughout production and processing chain. These residues (skins, crowns, cylinders, stems and pulp remnants) contain a high content of bioactive compounds, but generally not directly available and for that reason is necessary to extract and characterize the feasible bioactive compounds.These residues lack the search of new structures that could be easily used in food, nutraceutics and pharmaceutics industries. Therefore, the focus of this research work was to perform a compositional analysis (qualitative and quantitative) of pineapple by-products extracts to explore the potential of these fractions as added-value ingredients. Frozen pineapples by-products were submitted to a milling and pressing processes, creating a pineapple juice and a solid semi-dried extract. The soluble fraction was submitted to an extraction of the pineapple enzymes (Bromelain) and after this process, the soluble fraction was assessed for the presence of soluble carbohydrates. The insoluble part was submitted to hot aqueous extraction during 1 hour at 80 ºC with uniform stirring (100 rpm), promoting a hot solubilisation. The supernatant and the pellet of this extraction were separated, and the liquid were subjected to freeze-drying process to obtain better handled extracts. The prebiotic activity was tested for the different carbohydrates enriched extracts using frutooligosaccharide (FOS) as positive control. An initial screening was performed using different probiotic bacteria, such as Lactobacillus acidophilus Ki and Bifidobacterium lactis Bb12. The extracts with higher biological activity were used to determine compounds profile by HPLC and UPLC-MS, establishing and understanding the relationship between structure and activity. The insoluble fractions were analyzed in terms of lignin, cellulose and hemicellulose.To evaluate the MW of polysaccharides an ultra-hydrogel column was used, and the results showed that two major peaks of polysaccharides comprising MW of 2000 and 600 Da. Also, when using an Aminex® column for simple sugars analysis, the fractions presented high concentration of two monosaccharides glucose and fructose, as expected. The polysaccharides of higher MW were identified as being galactomannan. The insoluble fractions contained ca. 30% (w/w) of lignin being the most part soluble lignin, hemicellulose and cellulose represent ca. 35% (w/w). Through this research work, it was possible to characterize the carbohydrates presents in pineapple by-products and establish probiotic related activity.