Being one of the hazardous contaminants in the environment, continuous exposure to cadmium ions (Cd(II)) has been shown to severely affect the well being of both humans and animals. Therefore, development of a highly sensitive method to detect trace amounts of such substance in the environment acquires scientific pertinence. In this present work, carbon paste electrode modified with bis(benzylidene)ethelynediamine (BBE-CPE) was used for the determination of Cd(II) using square wave anodic stripping voltammetric (SWASV) technique. A response surface methodological approach employing the Box-Behnken design (BBD) based on four relevant variables viz. pH, deposition time, percentage ligand and deposition potential was used for optimizing the experimental conditions for detecting such ions. Under optimized conditions (supporting electrolyte: pH 4.5, deposition time: 350 s, ligand graphite composition: 6%, deposition potential: ‒1.1 V), a linear response over a wide range of Cd(II) concentrations (1–500 µg L−1) with low detection limit (0.4 µg L-1) and quantification limit (1.4 µg L-1) were observed with deposition time being the most impacting factor. Pertinently, the BBE-CPE developed here exhibited exceptional recovery of Cd(II) concentrations in the sea and tap water samples, comparable with that observed under simulated conditions, suggesting its applicability for a variety of real samples. © 2020 Trans Tech Publications Ltd, Switzerland.

Increasing energy demands call for sustainable alternative sources. Solid state fermentation (SSF) of raw oil palm frond leaves (OPFL) as the substrate to produce extracellular cellulases and xylanase by a novel Rhizopus oryzae UC2 (GenBank accession no. MF767597) was optimized. Optimum SSF conditions (30 °C, 40% moisture content, 2.0 × 108 spores/g inoculum size) yielded the maximum carboxymethyl cellulase (CMCase) (94.68 U/g), filter paperase (FPase) (25.46 U/g), β-glucosidase (145.47 U/g) and xylanase (213.99 U/g) activities, showing a broad pH range of between 6.0 and 12.0. Proteome analysis of crude enzyme cocktail revealed three β-glucosidases, as well as one endo-β-1,4-glucanase, exoglanase and endo-β-1,4-xylanase each. Activities of the enzyme complex were maximal at an acidic pH and temperature that ranged between pH 3.0–5.0 and 50–60 °C, respectively. In situ hydrolysis of OPFL released various concentrations of sugars viz. glucose (26.74 mg/g), xylose (1.44 mg/g), fructose (50.8 mg/g) and cellobiose (58.31 mg/g). Moreover, CMCase, FPase, β-glucosidase and xylanase exhibited half-lives of 5.13, 1.48, 18.81, 9.23 h when incubated at 60 °C, respectively. Thus, the desirable qualities of R. oryzae UC2 seen here supported its prospective biocatalytic role for timely and safe production of digestible carbohydrates from agro-industrial biomass for the subsequent biotransformation into biofuel. © 2019 Elsevier Ltd

Ananas comosus (L.) Merr is one of many commercially popular fruits in the cannery food industry that contributes to the increasingly mounting agro-industrial waste. In this study, a four−factor−three−level Box−Behnken design (BBD) that comprised of sonication time (A), solvent ratio (B), amplitude (C) and liquid−solid ratio (D) for the ultrasound−assisted extraction (UAE) of pineapple peels (PP) was utilized to optimize the yield of total phenolic content (TPC). Under an optimized UAE condition [5 min; 50 % of ethanol: water; 65 % of amplitude; 35:1 mL/g of liquid−solid ratio], the highest TPC from PP of 708.10 mg gallic acid equivalent (GAE)/g DW was achieved. Antioxidant capacity analysis of PP revealed a high total flavonoid content (TFC) with the IC50 for 2,2−diphenyl−1−picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP) of 1146.86 ± 11.83 mg QE/g, 11.83 mg/mL and 1578.07 ± 25.96 µM Fe (II)/100g, respectively. High-performance liquid chromatography (HPLC) analysis revealed that the major flavonoid in the phenolic profile of PP extracts being catechin followed by quercetin and gallic acid. The UAE of PP extracts exhibited higher TPC than known conventional extraction techniques, thus indicating its efficacy to recover satisfactory quantities of phenolics in PP under optimized conditions. © 2020 Penerbit UTM Press. All rights reserved.