Open Access Opinion Article

The Origins of Enzyme Catalysis and Reactivity: Further Assessments

Sosale Chandrasekhar

Asian Journal of Chemical Sciences, Page 38-47
DOI: 10.9734/ajocs/2021/v9i319075

Alternatives to conventional mechanisms of enzyme catalyzed reactions, although within the ambit of transition state theory, are explored herein. This is driven by reports of a growing number of enzymes forming covalently linked enzyme-substrate intermediates, which clearly deviate from the conventional Michaelis-complex mechanism. It is argued that the formation of the covalent intermediates can be accommodated within the framework of transition state theory and the original Pauling hypothesis. This also obviates the need to invoke intramolecular reactivity to explain enzymic accelerations. Thus, the covalent binding of a substrate distorted towards the transition state, with the binding being fully manifested in the ensuing transition state, would conform to the traditional endergonic pre-equilibrium mechanism. Intriguingly, an alternative exergonic formation of the covalent intermediate would also lead to catalysis: in this case, any of the three steps–covalent binding, turnover or product release–can be rate limiting. Although the exergonic mode has been dismissed previously as leading to a “thermodynamic pit” (Michaelis complex case), this view now needs to be reassessed as it seems inaccurate. Therefore, it remains for the enzyme to stabilize the various transition states via the multifarious mechanisms available to it. The Pauling hypothesis remains vindicated.

Open Access Original Research Article

Assesment of Biochemical Forage Quality of Sweet Sorghum [Sorghum bicolor (L.) Moench ssp. saccharatum]

Abdullah Oktem, Celal Yucel, Ayse Gulgun Oktem

Asian Journal of Chemical Sciences, Page 1-9
DOI: 10.9734/ajocs/2021/v9i319071

In this study, it was aimed to determine some forage quality characteristics of sweet sorghum genotypes in semi-arid climatic conditions. The experiment was set up in randomized complete block design with 4 replicates. Research was carried out in 2016 and 2017 under Harran Plain second crop conditions, Sanliurfa, Turkey. In the study 21 genotypes of sweet sorghum were used. Crude protein content, crude ash, acid detergent fiber (ADF), neutral detergent fiber (NDF), dry matter digestibility, dry matter consumption, were determined in the study. Significant differences were found between the genotypes for tested characteristics (P≤0.01). According to average of two years, crude protein content ranged from 4.20% (Tracy) to 5.90% (USDA S.Africa), crude ash from 4.44% (Theis) to 6.90% (Topper 76), acid detergent fiber (ADF) from 27.84% (Nebraska sugar) to 36.30% (USDA-Zaire). The highest NDF value was obtained from USDA-Zaire genotype (56.49%) whereas the lowest values were seen at N98 genotype (43.11%). Dry matter digestibility values were between 60.62% (USDA-Zaire) and 67.21% (Nebraska sugar), dry matter consumption between 2.14% and 2.85%. The highest relative feed value was obtained from N98 genotype (148.95) whereas the lowest values were seen at USDA-Zaire genotype (101.00). Net energy values ranged from 1.38 Mcal kg-1 (USDA-Zaire) to 1.50 Mcal kg-1 (Nebraska sugar). Considering the properties examined in terms of feed quality, it was seen that the crude protein content and net energy value was low. But ADF, NDF, digestible dry matter, dry matter consumption and relative feed values were within acceptable levels. Nebraska sugar, Topper 76, N98, Roma, M81E, Tracy and Corina genotypes were found as the best for forage quality in sweet sorghum. It was determined that sweet sorghum can be used as a forage source.

Open Access Original Research Article

Effects of Combining Antioxidants on the Oxidative Stability of Refined, Bleached and Deodorized Palm Olein during Continuous Deep Frying of Potato Chips

Hanafy A. Hashem, Rabie S. Farag, Abdel-Alrahman Naser, Montaser A. Mohamed

Asian Journal of Chemical Sciences, Page 11-19
DOI: 10.9734/ajocs/2021/v9i319072

In this study, the effect of a novel antioxidants composite system based on a synergetic composite between Tertiary butyl hydroquinone (TBHQ), Ascorbyl palmitate, citric acid, and Dimethicone have been evaluated against the classical common antioxidant system based on TBHQ at the highest permitted dose of 200 ppm during successive deep-frying cycles.  Also, the shelf life of fried food and its sensory performance and oil absorption content o fried food were comparatively studied. The Novel antioxidant composite system is a synergetic blend of an artificial antioxidant, TBHQ  and vitamin C  palmitate( Ascorbyl palmitate) as natural identical antioxidants, an effective sequestrant which is Citric acid and poly dimethyl siloxane as an anti-foaming system to obtain the highest oxidative stability impact during deep frying. The frying processes were carried at 180 ᴼC for sliced potato chips for 8 successive frying cycles.Sensory evaluation of the fried potato has been conducted under accelerated storage conditions to determine the effect of the oil oxidative stability on the shelf life of fried food. The oxidative degradation of the oil was evaluated by measuring different oxidation and degradation parameters for their respective peroxide value ( PV), free fatty acid( FFA %), the content of conjugated dienes, P-anisidine value,( p-A.V),  induction period (IP), and Lovibond color. The (%) of oil absorption in the potato chips was also measured. The sensory evaluation has been done for fried foods to evaluate the crunchiness and likability of obtained french fries. Results revealed that the jump in primary & secondary oxidation parameters as  PV and p- A.V.of palm olein after 8 successive frying cycles was very limited for the antioxidant composite system I  by only 1.842± 0.1 meq O2/ kg in PV and by 6.2315±0.45 for p-A.V. Same for FFA, the jump was limited for the antioxidant composite system I for only  0.084+/-0.005 as well. However, the final PV, FFA after the 8 frying cycles are still within the Codex and local Egyptian regulation limits the edible oil human usage. Same for other quality parameters like color jump was limited to 3.4 Red jumps on Lovi bond scale for composite I. Study proofed that palm olein fortified with 650 ppm of the antioxidant composite (I) consists of TBHQ, Ascorbyl palmitate, citric acid, and polydimethylsiloxane at the specified synergistic ratios gives outstanding stability to refined Palm olein during the successive deep frying up to 8 successive frying cycles. It also achieved less oil absorption for french fries by about 3.5% less than the same oil fortified with 200 ppm TBHQ, which is the highest permitted dose of this strong antioxidant. (P≤0.05). Furthermore, sensory evaluation of the fried potatoes has been improved with the novel antioxidant system compared to theclassical TBHQ system.

Open Access Original Research Article

Characterization of the Structure of 2-(4-methyl-2 Phenyl-4, 5-dihydrooxazol-4-ylmethyl)-isoindole-1, 3-dione by 1D, COSY and HSQC 2D NMR Spectroscopy

Khadim Dioukhane, Younas Aouine, Asmae Nakkabi, Salaheddine Boukhssas, Hassane Faraj, Anouar Alami

Asian Journal of Chemical Sciences, Page 30-37
DOI: 10.9734/ajocs/2021/v9i319074

The identity of the 2-(4-Methyl-2-phenyl-4,5-dihydrooxazol-4-ylmethyl)-isoindole-1,3-dione, previously synthesized in our laboratory, was proven without doubt by means of 1D and 2D NMR spectroscopy. Two-dimensional NMR spectroscopy played a major role. The analysis of the 2D-COSY spectrum of isoindoline-1,3-dione derivative shows a perfect correlation between neighboring protons. Thus, a correlation was noted between the protons of the phthalimide, H(8) and H(9) on the one hand and H(8') and H(9') on the other hand. The analysis of the 2D-HSQC spectrum of the studied compound indicates a faultless correlation between protons and adjacent carbons, and no correlation in the case of all quaternary carbons.

Open Access Review Article

Review of Neural Network Algorithm and Its Application in Reactive Distillation

Huihui Wang, Ruyang Mo

Asian Journal of Chemical Sciences, Page 20-29
DOI: 10.9734/ajocs/2021/v9i319073

Artificial Neural Networks (ANN) can accurately identify and learn the potential relationship between input and output, and have self-learning capabilities and high fault tolerance, which can be used to predict or optimize the performance of complex systems. Reactive distillation integrates reaction and rectification into one device, so that the two processes occur at the same time and at the same place, but at the same time it also produces highly nonlinear robust behavior, making its process control and optimization unable to use conventional methods. Instead, neural network algorithms must be used. This paper briefly describes the research progress of neural network algorithms and reactive distillation technology, and summarizes the application of neural network algorithms in reactive distillation, aiming to provide reference for the development and innovation of industry technology.