Search

Biodiesel is a green and renewable alternative energy source which can be produced through lipase‐catalyzed transesterification process. Enzymatic biodiesel production has generated much interest owing to its environmentally friendly process, low wastewater treatment requirements and easy product separation. In this work, we attempt to review some of the recent patents and state‐of‐the‐art technology in lipase‐catalyzed transesterification for biodiesel production including feedstock, lipases, novel carriers and process factors. This work will provide useful guidance for researchers to develop cost efficient process for production of biodiesels. [ABSTRACT FROM AUTHOR]

Present work encapsulated metal ion dopped‐Candida rugosa lipase (CRL) into ZIF structure through biomimetic mineralization and evaluated hydrolytic activity of the immobilized lipase using a biphasic system. Magnesium ion (Mg2+) doped‐CRL with high hydrolytic activity (237 % of free CRL) was successfully synthesized. Circular dichroism and fluorescence spectroscopy analysis revealed Mg2+ doping has changed the conformation of CRL resulted in enhanced structural stability of CRL. The synthesized CRL/Mg2+@ZIF‐8 had a mesoporous (3.88 nm) structure with good crystallinity. Mg2+ doping increased the catalytic activity, substrates affinity (lower Km of 0.4102 mM) and catalytic stability of immobilized CRL. Catalytic activity of CRL/Mg2+@ZIF‐8 (0.25±0.012 U) was two‐fold higher than that of CRL@ZIF‐8 (0.10±0.008 U). The synthesized CRL/Mg2+@ZIF‐8 was used in biosensing of a protox‐inhibiting herbicides (nitrofen) in fruit samples. CRL/Mg2+@ZIF‐8 can be used for biosensing of nitrofen with wide detection range (0‐50 μM), low detection limit (0.47 μM) and good recovery rate. [ABSTRACT FROM AUTHOR]

Summary: The antioxidant activity and stability of endogenous peptides isolated from farmed hybrid catfish (Clarias macrocephalus × Clarias gariepinus) muscle (EPC) were characterised. EPC contained 69 peptides with 8–24 amino acid residues, varying hydrophobic amino acid (HBA) content and distinct sequences. Among the top five, peptides discovered in EPC were ARHSYGMLYCSCPPND, DTQAARKSDDDD, AEFPCGDRRC, AAVTEELFFAGL and LILQRRKFLRMKREKYGFIYKTHL. Histidine (16.33%) and tryptophan (15.66%) were the most common amino acids found in EPC. EPC demonstrated concentration‐dependent free radical (DPPH•/ABTS•+) and hydroxyl radical (OH•) scavenging activities, as well as metal chelating ability. The effect of pH, heating temperature and in vitro digestion on EPC's DPPH• scavenging activity was studied. Lowering the pH and increasing the heating temperature to 90 °C increased the DPPH• inhibitory activity. However, after in vitro digestion, around 44% of DPPH• inhibition was reduced. The findings confirmed that farm‐raised hybrid catfish muscle contained endogenous peptides with antioxidant properties. [ABSTRACT FROM AUTHOR]

Summary: The chemical characteristics and volatile compounds profiles in distinct anatomical sites of a farm‐raised hybrid catfish (Clarias macrocephalus × Clarias gariepinus) were investigated. Total haem proteins, trimethylamine‐nitrogen, TBARS, n‐9 oleic acid, n‐6 linoleic acid and total concentration of all volatile compounds were all higher in the lateral line with the maximum redness index (p < 0.05). Dorsal muscle lipid contained more eicosapentaenoic acid and docosahexaenoic acid than the other two muscles (p < 0.05). Ventral muscle exhibited the highest fat content (p < 0.05) and was the only muscle discovered to have n‐3 linolenic acid. Geosmin and 2‐methylisoborneol (2‐MIB) were found in all three muscles. Despite the fact that 2‐MIB and geosmin are lipophilic compounds, their distribution was unaffected by fat content, with the highest levels in the lateral line (p < 0.05). Odour activity values (OAV) and sensory analyses revealed that not only 2‐MIB and geosmin but also (E)‐2‐nonenal and 1‐octen‐3‐ol, intensified the earthy and muddy odour in catfish muscles. The total off‐odour of catfish muscles was influenced by n‐9 oleic acid and n‐6 linoleic acid, according to the correlation analysis. The off‐odour compounds had a substantial negative connection with total n‐3 PUFA, as well as the irrelevance with fat content, according to this study. [ABSTRACT FROM AUTHOR]

Summary: The potential applicability of β‐carotene‐loaded nanoemulsion (CNE) as a natural colorant in non‐smoked sausage made from goat meat surimi‐like material (GMS) was elucidated. The effect of CNE content (0–30 g 100 g−1) on the physicochemical characteristic, oxidative stability and β‐carotene remaining during cold storage (4 °C) was determined. The higher the CNE, the greater the a*, b* and redness index with the lower L*, and colour likeness score. CNE content had a little impact on the moisture content, aw and pH of sausages over storage period. However, the expressible drip, breaking force and deformation were largely influenced by the CNE content. All CNE‐containing sausages displayed a superior oxidative stability to control. Among CNE‐incorporated samples, the lowest lipid oxidation and β‐carotene degradation were noticeable in the sausage with 10 g 100 g−1 CNE. Thus, the CNE at 10 g 100 g−1 was a promising functional colorant for emulsion sausage made from GMS. [ABSTRACT FROM AUTHOR]

Summary: Gelling characteristics of bigeye snapper (Priacanthus tayenus) surimi functionalised by lecithin at different concentrations were investigated. Lecithin at ≤1 g 100 g−1 had no impact on breaking force and deformation (P > 0.05). Expressible drip tended to decrease with increasing lecithin level up to 1 g 100 g−1. Lecithin at 1–3 g 100 g−1 improved the whiteness (P < 0.05). Jointed clusters were formed in the gel microstructure with 1 g 100 g−1 lecithin. Gel without and with 1 g 100 g−1 lecithin had the same texture profile and likeness scores (texture, odour and flavour) (P > 0.05). Peroxide value, TBARS content and rancid odour score of gels were changed considerably during refrigerated storage (4 °C/polyethylene bag) for 15 days but lower values of all indices were noticeable in gel with lecithin. Therefore, lecithin at 1 g 100 g−1 was the optimum concentration for stabilising the texture, improving the water holding capacity, whitening the colour and retarding the lipid oxidation of bigeye snapper surimi gel. [ABSTRACT FROM AUTHOR]

Summary: Astrocytes play an important role in the physiological functions of the central nervous system. In this study, contact potential differences (CPD) and capacitance gradients of the cell bodies and glial filaments of astrocytes were measured. Charge propagation properties in the astrocyte gap junctions were also studied using multimode Atomic Force Microscopy (AFM) at nanometre resolution. The CPD of the cell bodies and glial filaments were 324.2 ± 138.4 and 119.1 ± 31.7 mV, respectively. The measured capacitance gradients were 1.51 ± 0.31 and 1.98 ± 0.32 zF nm–1, respectively. The gap junctions in the astrocytes showed no charge propagation and were not electrically sensitive. This furthers our understanding of astrocytes and other types of neuroglia. Lay Description: Neuroglia cells play important structural and functional roles in central nervous system (CNS). Neuroglia cells exceed the number of neurons by 10∼50 and can be divided into macroglia and microglia. Astrocytes are macroglia and are the largest and most abundant cells in the CNS. Astrocytes lack axons and dendrites and do not propagate action potentials. They have few cytoplasmic organelles, but possess abundant glial filaments, the main components of the cytoskeleton. Glial filaments are composed of the glial fibrillary acidic protein (GFAP). Astrocytes produce intercellular calcium waves in their gap junctions mediated through receptor activator (such as glutamate) to permit signal transduction._ENREF_5 In addition to their role in the support and nutrition of neurons, astrocytes are involved in various types of CNS activity including: (1) cytokine secretion for neuronal survival, growth and differentiation; (2) protection from brain injury; (3) modulation of the blood brain barrier; and (4) neuronal immunity. Bidirectional crosstalk between the astrocytes and neurons exists. Astrocytes can be activated by neurotransmitters released and can themselves release gliotransmitters to act upon neurons. Astrocytes are closely related to various disease states, including epilepsy and Alzheimer's disease. In this study, the electrical properties of astrocytes, including the contact potential difference (CPD) and capacitance gradients of the cell bodies and glial filaments, and charge propagation in the gap junctions were investigated at the nanometer level using quantitative Kelvin Probe Force Microscopy (KPFM) and Electrostatic Force Microscopy (EFM). The CPD of the cell bodies and glial filaments of the astrocytes were 324.2 mV and 119.1 mV, respectively. Capacitance gradients of the cell bodies and glial filaments of the astrocytes were 1.51 zF/nm and 1.98 zF/nm, respectively. Gap junctions in the astrocytes do not perform charge propagation functions and the astrocytes are not electrically sensitive. One should note that these results from KPFM and EFM were measured on dried cell and the situation might be different when studying in operando environment, still these findings aid our understanding of the electrical properties and functions of astrocytes, and further our knowledge of the electrical properties of the CNS. [ABSTRACT FROM AUTHOR]

Moisture migration in food causes deleterious effects on food quality such as loss of crispiness in ice cream cones, drying of chocolate with liquid centers, sugar bloom and cracking of compound/chocolate coating. The present study aimed to investigate the relationship between physicochemical properties of confectionery coating fats such as fatty acids and triacylglycerol (TAG) composition, solid fat contents, rheological and crystalline properties with their moisture barrier property. Coating fats with high content of trisaturated and desaturated TAG; and high SFC at 25 °C were found to have significant ( P < 0.05) positive correlation with its moisture barrier property. These fats were able to crystallize into highly crystalline materials (high SFC) with small crystal size and dense networks. Thus, these fats were able to significantly delay moisture migration. Nevertheless, some of the highly crystalline fats also had high G′ value indicating poor mechanical properties and higher tendency of such fats to crack. In order to have good moisture barrier property, coating fats need to have sufficient solids with small crystal size and dense networks; and also low G′ value. Wafer coated with good moisture barrier fat showed less cracking during storage. [ABSTRACT FROM AUTHOR]

The present study examined the physical properties of soybean oleogels and commercial confectionery filling fats and evaluated the oil migration properties in model praline systems. Soybean oleogels were prepared using different oleogelators namely monoglyceride (MAG oleogels) and a mixture of sorbitan tri-stearate (STS) with lecithin (50:50) (Lec-STS oleogels). Both MAG oleogels and Lec-STS oleogels demonstrated a flat solid fat content (SFC) profile with zero SFC at 40 °C. At low temperature, MAG oleogels and Lec-STS oleogels demonstrated a non-flowing gel-like property due to the ability of the oleogelator to entrap liquid oil. In addition, oleogels also showed thixotropic behavior indicating the possible capability to prevent migration of filling fats to coatings and also good flow ability during pumping though manufacturing equipment. The textural property of oleogels also did not change significantly upon storage indicating good structural stability. When used as in a model praline system, oleogels demonstrated a migration delaying property. [ABSTRACT FROM AUTHOR]

Monoacylglycerols (MAG) are nonionic emulsifiers, widely used in food, pharmaceutical, and cosmetic industries. Besides the bulk applications in food and dairy industries, pure MAG are also of great interest in synthetic organic chemistry where they are used as synthetic intermediates and as chiral building blocks. Reaction routes for MAG production including direct esterification of glycerol and fatty acids, interesterification between glycerol and fatty acid esters, glycerolysis of TAG and glycerol, partial hydrolysis of TAG, as well as alcoholysis of TAG. During the past few years, extensive efforts have been made for high yield of MAG from the reaction systems, using either chemical or enzyme as catalysts. And strategies have been developed aiming at the increase of MAG selectivity. An overview is given for such strategies targeting on the increase of MAG yield from the reaction systems. In particular, the mesoporous siliceous framework porosity and the surface hydrophilicity of the heterogeneous catalysts, as well as the solvation within the reaction systems caused by reaction medium, are discussed carefully to clearly highlight how catalysts and reaction medium can help to increase the MAG selectivity (MAG selectivity in the present paper means selectivity to form MAG instead of DAG). [ABSTRACT FROM AUTHOR]

The present study aimed to produce MAG through low-temperature chemical glycerolysis. Over 80% MAG yield with 97% TAG conversion was obtained within short reaction times at temperature of 35-55°C, when tert-butanol (TB) or tert-pentanol (TP) was used as reaction medium and sodium hydroxide (NaOH) as catalyst. TB gave a faster reaction rate than TP. Catalysts were important for the low-temperature chemical glycerolysis reaction. Of the eight common base catalysts evaluated, only NaOH and potassium hydroxide (KOH) were effective, and NaOH was better than KOH. Reaction parameters were studied and optimized. The optimum conditions were TB dosage 3:1 (TB to oil in weight ratio), NaOH concentration 0.45 wt% based on oil, molar ratio of glycerol to oil 5:1. Under these conditions, similar MAG yield and TAG conversion was also observed by Novozym 435 catalyzed glycerolysis, however, a 4 h reaction was required. Practical applications: The process of NaOH catalyzed chemical glycerolysis for MAG production in TB solvent system described in this study provides several advantages including short reaction time and high product yield, which is potential for industrial considerations. [ABSTRACT FROM AUTHOR]

β-Hydroxy-β-methylbutyrate (HMB) is reported to have ergogenic benefits such as reducing muscle wasting, promoting exercise performance and skeletal muscle hypertrophy. When used as a dietary feed, it has been found to improve colostral milk fat and the growth of piglets. Medium chain triacylglycerols (MCT) are a good energy source as they can be subjected to β-oxidation in the liver without being stored as fats. When used as animal feed, HMB-MCT complexes are reported to stimulate growth and produce leaner meat product. A high yield two-steps chemo-enzymatic pathway for synthesis of HMB-MCT complexes has been developed. Ethyl HMB ester was first synthesized using a chemical catalyst. Following that, it was transesterified with MCT by using a biocatalyst. Approximately 85 wt% of HMB-MCT complexes can be achieved using this two-step synthetic pathway. The reaction mechanism and some of the reaction parameters were also briefly elucidated. [ABSTRACT FROM AUTHOR]

Crude oils contain phospholipids which are removed during the degumming stage of refining. This valuable product has been used as an emulsifier in food, feed and cosmetics. Most of the naturally occurring phospholipids contain unsaturated fatty acids which are prone to oxidation. Thus, it is worth modifying the structure of phospholipids to improve their physical, chemical and functional properties. This paper considers the possibilities of modifying the phospholipids structure and the properties of the modified compounds. [ABSTRACT FROM AUTHOR]

Camelina sativa oil is characterized by its high content (up to 40 wt%) of α-linolenic acid and its unique flavor. It is considered to have beneficial health properties and is suitable for food and cosmetic uses. In the present study, response surface methodology was used to optimize processing parameters for bench-scale deodorization of camelina oil. The mathematical models generated described the effects of process parameters (temperature, steam flow, time) on several deodorization quality indicators: free fatty acids (FFA), trans fatty acids (TFA), color, and polymerized triglycerides (PTG). These newly established models can be used as a tool to identify optimum deodorization process conditions within chosen constraints. Based on the optimization of minimum retained FFA with the constraint of a maximum allowable TFA, deodorization parameters can be defined. At a constant steam flow rate of 42 ml/h, a temperature range of 210-220 °C, and deodorization time of 70-120 min were defined. 220 °C appears to be a critical upper temperature limit; above this temperature, isomerization rates significantly increase. [ABSTRACT FROM AUTHOR]

Review: 72 refs. [ABSTRACT FROM AUTHOR]