Soluble solid content (SSC) is one of the important traits that indicate the ripeness of banana fruits.
Determination of SSC for banana often requires destructive laboratory analysis on the fruit. An impedance measurement technique was investigated as a non-destructive approach for SSC determination of bananas. A pair of electrocardiogram (ECG) electrode connected to an impedance analyser board was used to measure the impedance value of bananas over the frequency of 19.5 to 20.5 KHz. The SSC measurement was conducted using a pocket refractometer and data was analysed to correlate SSC with impedance values. It was found that the mean of impedance, Z decreased from 10.01 to 99.93 KΩ at the frequency of 20 KHz, while the mean value of SSC increased from 0.58 to 4.93 % Brix from day 1 to day 8. The best correlation between impedance and SSC was found at 20 KHz, with the coefficient of determination, R2 of 0.87. This result indicates the potential of impedance measurement in predicting SSC of banana fruits.
Two optimization strategies, codon usage modification and glycine supplementation, were adopted to improve the extracellular production of Bacillus sp. NR5 UPM β-cyclodextrin glycosyltransferase (CGT-BS) in recombinant Escherichia coli. Several rare codons were eliminated and replaced with the ones favored by E. coli cells, resulting in an increased codon adaptation index (CAI) from 0.67 to 0.78. The cultivation of the codon modified recombinant E. coli following optimization of glycine supplementation enhanced the secretion of β-CGTase activity up to 2.2-fold at 12 h of cultivation as compared to the control. β-CGTase secreted into the culture medium by the transformant reached 65.524 U/mL at post-induction temperature of 37 °C with addition of 1.2 mM glycine and induced at 2 h of cultivation. A 20.1-fold purity of the recombinant β-CGTase was obtained when purified through a combination of diafiltration and nickel-nitrilotriacetic acid (Ni-NTA) affinity chromatography. This combined strategy doubled the extracellular β-CGTase production when compared to the single approach, hence offering the potential of enhancing the expression of extracellular enzymes, particularly β-CGTase by the recombinant E. coli.
β-glucosidases (Bgl) are widely utilized for releasing non-reducing terminal glucosyl residues. Nevertheless, feedback inhibition by glucose end product has limited its application. A noticeable exception has been found for β-glucosidases of the glycoside hydrolase (GH) family 1, which exhibit tolerance and even stimulation by glucose. In this study, using local isolate Trichoderma asperellum UPM1, the gene encoding β-glucosidase from GH family 1, hereafter designated as TaBgl2, was isolated and characterized via in-silico analyses. A comparison of enzyme activity was subsequently made by heterologous expression in Escherichia coli BL21(DE3). The presence of N-terminal signature, cis-peptide bonds, conserved active site motifs, non-proline cis peptide bonds, substrate binding, and a lone conserved stabilizing tryptophan (W) residue confirms the identity of Trichoderma sp. GH family 1 β-glucosidase isolated. Glucose tolerance was suggested by the presence of 14 of 22 known consensus residues, along with corresponding residues L167 and P172, crucial in the retention of the active site's narrow cavity. Retention of 40% of relative hydrolytic activity on ρ-nitrophenyl-β-D-glucopyranoside (ρNPG) in a concentration of 0.2 M glucose was comparable to that of GH family 1 β-glucosidase (Cel1A) from Trichoderma reesei. This research thus underlines the potential in the prediction of enzymatic function, and of industrial importance, glucose tolerance of family 1 β-glucosidases following relevant in-silico analyses.
Lard adulteration in processed foods is a major public concern as it involves religion and
health. Most lard discriminating works require huge lab-based equipment and complex sample
preparation. The objective of the present work was to assess the feasibility of dielectric
spectroscopy as a method for classification of fats from different animal sources, in particular,
lard. The dielectric spectra of each animal fat were measured in the radio frequency of 100
Hz – 100 kHz at 45°C to 55°C. The fatty acid composition of each fat was studied by using
data from gas chromatography mass spectrometry (GCMS) to explain the dielectric behaviour
of each fat. The principal component analysis (PCA) and artificial neural network (ANN)
were used to classify different animal fats based on their dielectric spectra. It was found that
lard showed the highest dielectric constant spectra among other animal fats, and was mainly
affected by the composition of C16 and C18 fatty acids. PCA classification plot showed clear
performance in classifying different animal fats. Finally, ANN classification showed different
animal fats were classified into their respective groups effectively at high accuracy of 85%.
Dielectric spectroscopy, in combination with quantitative analysis, was concluded to provide
rapid method to discriminate lard from other animal fats.
Winged bean [Psophocarpus tetragonolobus (L.) DC.] seed is a potential underexploited source of vegetable protein due to its high protein content. In the present work, undefatted and defatted winged bean seed hydrolysates, designated as UWBSH and DWBSH, respectively were produced separately by four proteolytic enzymes namely Flavourzyme, Alcalase, Bromelain, and Papain using pH-stat method in a batch reactor. Enzymatic hydrolysis was carried out over a period of 0.5 to 5 h. UWBSH and DWBSH produced were tested for their ACE inhibitory activity in relation to the hydrolysis time and degree of hydrolysis (DH). Maximum ACE inhibitory activity, both for UWBSH and DWBSH, were observed during 3 to 5 h of hydrolysis. Both, UWBSH (DH 91.84 %), and DWSBH (DH 18.72 %), produced by Papain at 5 h hydrolysis, exhibited exceptionally high ACE inhibitory activity with IC50 value 0.064 and 0.249 mg mL(-1), respectively. Besides, papain-produced UWBSH and DWBSH were further fractionated into three fractions based on molecular weight (UWBSH-I, <10 kDa; UWBSH-II, <5 kDa; UWBSH-III, <2 kDa) and (DWBSH-I, <10 kDa; DWBSH-II, <5 kDa; DWBSH-III, <2 kDa). UWBSH-III revealed the highest ACE inhibitory activity (IC50 0.003 mg mL(-1)) compared with DWBSH-III (IC50 0.130 mg mL(-1)). The results of the present investigation revealed that winged bean seed hydrolysates can be explored as a potential source of ACE inhibitory peptides suggesting their uses for physiological benefits as well as for other functional food applications.
The response surface method was applied in this study to improve cellulase production from oil palm empty fruit bunch (OPEFB) by Botryosphaeria rhodina. An experimental design based on a two-level factorial was employed to screen the significant environmental factors for cellulase production. The locally isolated fungus Botryosphaeria rhodina was cultivated on OPEFB under solid-state fermentation (SSF). From the analysis of variance (ANOVA), the initial moisture content, amount of substrate, and initial pH of nutrient supplied in the SSF system significantly influenced cellulase production. Then the optimization of the variables was done using the response surface method according to central composite design (CCD). Botryosphaeria rhodina exhibited its best performance with a high predicted value of FPase enzyme production (17.95 U/g) when the initial moisture content was at 24.32%, initial pH of nutrient was 5.96, and 3.98 g of substrate was present. The statistical optimization from actual experiment resulted in a significant increment of FPase production from 3.26 to 17.91 U/g (5.49-fold). High cellulase production at low moisture content is a very rare condition for fungi cultured in solid-state fermentation.
This study presents the effect of carbon to nitrogen ratio (C/N) (mol/mol) on the cell growth and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) accumulation by Comamonas sp. EB172 in 2 L fermenters using volatile fatty acids (VFA) as the carbon source. This VFA was supplemented with ammonium sulphate and yeast extract in the feeding solution to achieve C/N (mol/mol) 5, 15, 25, and 34.4, respectively. By extrapolating the C/N and the source of nitrogen, the properties of the polymers can be regulated. The number average molecular weight (M n ) of P(3HB-co-3HV) copolymer reached the highest at 838 × 10(3) Da with polydispersity index (PDI) value of 1.8, when the culture broth was supplemented with yeast extract (C/N 34.4). Tensile strength and Young's modulus of the copolymer containing 6-8 mol% 3HV were in the ranges of 13-14.4 MPa and 0.26-0.34 GPa, respectively, comparable to those of polyethylene (PE). Thus, Comamonas sp. EB172 has shown promising bacterial isolates producing polyhydroxyalkanoates from renewable carbon materials.
Palm olein has been commercially used as frying medium in batch deep-fat frying. During
frying, the oil usually deteriorates due to the exposure to high temperature. In this study, a
fluorescence spectroscopy technique was applied to monitor the deterioration of refined,
bleached, and deodorized palm olein (RBDPO) in batch deep-fat frying. 22.5 kg of French fries
were used as the frying material. In 30 batches, the french fries were intermittently fried at 185
± 5°C for eight hours a day over five consecutive days capturing 40 hours. The fluorescence
intensity of the RBDPO was recorded with excitation at 390 nm and resulting emission of 465
nm. The fluorescence intensity of the RBDPO over five days of frying decreased considering
the wavelength range of emission 430-640 nm and excitation 360-430 nm. The decreased in
intensity of fluorescence emission and excitation spectra were inversely correlated with the FFA
content of the oil samples. This study demonstrates the potential of fluorescence spectroscopy
in monitoring the deterioration of RBDPO during batch deep-fat frying.