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Volume 6 Number 1 March 2021

Evaluation of Shell-Derived Calcium Oxide Catalysts for the Production of Biodiesel Esters from Cooking Oils


Authors: Ngee Sing Chong ; Francis Uchenna Okejiri ; Saidi Abdulramoni ; Shruthi Perna ; Beng Guat Ooi
Pages: 20-27
DOI: doi.org/10.32861/ajc.61.20.27
Abstract
Due to the high cost of feedstock and catalyst in biodiesel production, the viability of the biodiesel industry has been dependent on government subsidies or tax incentives. In order to reduce the cost of production, food wastes including eggshells and oyster shells have been used to prepare calcium oxide (CaO) catalysts for the transesterification reaction of biodiesel synthesis. The shells were calcined at 1000 °C for 4 hours to obtain CaO powders which were investigated as catalysts for the transesterification of waste cooking oil. The catalysts were characterized by Fourier Transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), and X-ray fluorescence (XRF) spectroscopy. Reaction parameters such as methanol-to-oil molar ratio, CaO catalyst concentration, and reaction time were evaluated and optimized for the percentage conversion of cooking oil to biodiesel esters. The oyster-based CaO showed better catalytic activity when compared to the eggshell-based CaO under the same set of reaction conditions.

Application of Lactobacillus helveticus CNRZ 32 to Control the Microbial Contaminants in Cheese by Addition of Bacterial Extracts or by In Situ Production of Bioactive Metabolites


Authors: Mohamed F. El-Sayad ; Gamal A. Ibrahim ; Osama M. Sharaf ; Nadia M. Dabiza
Pages: 12-19
DOI: doi.org/10.32861/ajc.61.12.19
Abstract
Microbial spoilage of cheese represents a major concern from both health and economic views. The addition of food preservatives is considered the most applied strategy to ensure food quality and to control microbial contamination. It well established that natural preservatives such as Nisin and Natamycin are of great effectiveness against a wide range of microbial concerns, but the lack of wide spectrum effect induces looking for more efficient alternatives. This research suggests alternative treatments to be evaluated side by side with both Nisin and Natamycin within real cheese models to control microbial contamination during the storage period. To evaluate this, two varieties of cheese were manufactured and inoculated with a set of pathogen and cheese spoiling microorganisms. Talaga cheese batches were separately treated with extract of MRS that previously fermented by Lactobacillus helveticus CNRZ 32, Nisin and Natamycin at Free State and Chitosan Nanoparticles-loaded state to become 6 treatments (T1 – T6) other than the control (C). The same treatments were applied to Karish cheese batches, in addition to inoculation of Lactobacillus helveticus CNRZ 32 1% (v/v) in the seventh batch. Upon microbiological analyses, results show that T2; the extract loaded on Chitosan Nanoparticles completely reduced the count of all pathogens and spoiling populations after two weeks of cold storage (2 – 6oC) in Talaga cheese. In the case of Karish cheese, the 7th batch treated with Lactobacillus helveticus CNRZ 32 inoculation had no pathogenic nor spoiler growth after one week of cold storage (2 – 6oC). These results suggest that Lactic acid bacteria especially Lactobacillus helveticus CNRZ 32 can efficiently ensure the safety and quality of cheese if applied in appropriate form.

Some Regularities Inherent in the Balance 2∙f(O) – f(H) Formulated for an Electrolytic System with Symproportionation Reactions Involved


Authors: Anna Maria Michałowska-Kaczmarczyk ; Tadeusz Michałowski
Pages: 1-11
DOI: doi.org/10.32861/ajc.61.1.11
Abstract
The general properties of the balance f12 = 2∙f(O) – f(H), as the linear combination of elemental balances: f1 = f(H) for H and f2 = f(O) for O, formulated for electrolytic systems, are presented. These properties/regularities are inherently related to linear combination (LC) of f12 with charge (f0) and other elemental/core balances fk = f(Yk) (Yk ≠ H, O), expressed by, where the multipliers dk are involved with oxidation numbers (ONs) of the elements in the system in question. The linear dependence or independence of f12 from f0,f3,…, fK, expressed by LC, provides the general criterion distinguishing between non-redox and redox systems. The f12 is the primary form of Generalized electron balance (GEB), completing the set of K independent balances f0,f12,f3,…,fK needed for the solution of a redox system according to GATES/GEB principles. For the solution of a non-redox system, the set of K–1 independent equations f0,f3,…,fK is required. In this formulation, the terms: ONs, oxidant, reductant, and equivalent mass are derivative/redundant concepts. These properties/regularities of f12 are illustrated here by a redox system where symproportionation reactions occur.