Search

The research aims were to construct an air-breathing paper-based microfluidic fuel cell (paper-based μ FC) and to evaluated it with different soft drinks to provide energy for their prospective use in portable devices as an emergency power source. First, in a half-cell configuration, cyclic voltammetry showed that glucose, maltose, and fructose had specific oxidation zones in the presence of platinum-ruthenium on carbon (PtRu/C) when they were individual. Still, when they were mixed, glucose was observed to be oxidized to a greater extent than fructose and maltose. After, when a paper-based μ FC was constructed, PtRu/C and platinum on carbon (Pt/C) were used as anode and cathode, the performance of this μ FC was mostly influenced by the concentration of glucose present in each soft drink, obtaining maximum power densities at room temperature of 0.061, 0.063, 0.060, and 0.073 mW cm − 2 for Coca Cola ® , Pepsi ® , Dr. Pepper ® , and 7up ® , respectively. Interestingly, when the soft drinks were cooled, the performance was increased up to 85%. Furthermore, a four-cell stack μ FC was constructed to demonstrate its usefulness as a possible power supply, obtaining a power density of 0.4 mW cm − 2 , using Coca Cola ® as fuel and air as oxidant. Together, the results of the present study indicate an alternative application of an μ FC using soft drinks as a backup source of energy in emergencies.

Alternative sources of antioxidant dietary fibre, such as juice by-products, can be used in the prevention of obesity and its complications. In this study, the nutraceutical compounds of mango, guava and peach by-products from the juice industry were characterized. Mango and peach by-products presented an adequate balance of insoluble/soluble dietary fibre, as well as a high content of carotenoids (27.9 and 2.4 mg β-carotene/g, respectively) and polyphenols (102.0 and 83.6 GAE mg/g, respectively). Guava by-product presented the highest content of insoluble dietary fibre (74%). Several phytosterols and saponins were identified in all by-products. Juice by-products decreased the activity of α-amylase, and scavenged DPPH and nitric oxide radicals. An in vivo study was carried out in high fat and fructose (HF/HFr) diet-fed rats. Guava by-product decreased bodyweight gain (8%) and peach and mango by-products reduced hyperglycaemia (~25%). Hepatic steatosis was reduced by all by-products. Juice by-products improved some complications of obesity.