Agmatine Production by Aspergillus oryzae Is Elevated by Low pH during Solid-State Cultivation.

Sake (rice wine) produced by multiple parallel fermentation (MPF) involving Aspergillus oryzae (strain RW) and Saccharomyces cerevisiae under solid-state cultivation conditions contained 3.5 mM agmatine, while that produced from enzymatically saccharified rice syrup by S. cerevisiae contained <0.01 mM agmatine. Agmatine was also produced in ethanol-free rice syrup prepared with A. oryzae under solid-state cultivation (3.1 mM) but not under submerged cultivation, demonstrating that A. oryzae in solid-state culture produces agmatine. The effect of cultivation conditions on agmatine production was examined. Agmatine production was boosted at 30°C and reached the highest level (6.3 mM) at pH 5.3. The addition of l-lactic, succinic, and citric acids reduced the initial culture pHs to 3.0, 3.5, and 3.2, respectively, resulting in a further increase in agmatine accumulation (8.2, 8.7, and 8.3 mM, respectively). Homogenate from a solid-state culture exhibited a maximum l-arginine decarboxylase (ADC) activity (74 pmol · min-1 · µg-1) at pH 3.0 at 30°C; homogenate from a submerged culture exhibited an extremely low activity (<0.3 pmol · min-1 · µg-1) under all conditions tested. These observations indicated that efficient agmatine production in ethanol-free rice syrup is achieved by an unidentified low-pH-dependent ADC induced during solid-state cultivation of A. oryzae, even though A. oryzae lacks ADC orthologs and instead possesses four ornithine decarboxylases (ODC1 to ODC4). Recombinant ODC1 and ODC2 exhibited no ADC activity at acidic pH (pH < 4.0), suggesting that other decarboxylases or an unidentified ADC is involved in agmatine production.IMPORTANCE It has been speculated that, in general, fungi do not synthesize agmatine from l-arginine because they do not possess genes encoding arginine decarboxylase. Numerous preclinical studies have shown that agmatine exerts pleiotropic effects on various molecular targets, leading to an improved quality of life. In the present study, we first demonstrated that l-arginine was a feasible substrate for agmatine production by the fungus Aspergillus oryzae RW. We observed that the productivity of agmatine by A. oryzae RW was elevated at low pH only during solid-state cultivation. A. oryzae is utilized in the production of various Asian fermented foods. The saccharification conditions optimized in the current study could be employed not only in the production of an agmatine-containing ethanol-free rice syrup but also in the production of many types of fermented foods, such as soy sauce (shoyu), rice vinegar, etc., as well as for use as novel therapeutic agents and nutraceuticals.

Evaluation of Honey and Rice Syrup as Replacements for Sorbitol in the Production of Restructured Duck Jerky.

The aim of this study was to evaluate the potential of natural humectants such as honey and rice syrup to replace sorbitol in the production of restructured duck jerky. Each humectant was mixed at 3%, 6%, and 10% (wt/wt) concentrations with the marinating solution. The values of water activity and the moisture-to-protein ratio of all of the samples were maintained below 0.75. Jerky samples treated with honey retained more moisture than those exposed to other treatments. Among all samples, those treated with 10% sorbitol produced the highest processing yield and the lowest shear force values. The highest L* value and the lowest b* value were observed for the sorbitol-treated sample, followed by the rice syrup- and honey-treated samples. Duck jerky samples treated with 10% honey showed the highest scores for the sensory parameters evaluated. The overall acceptability scores of samples treated with rice syrup were comparable with those of samples treated with sorbitol. Microscopic observation of restructured duck jerky samples treated with honey showed stable forms and smaller pores when compared with other treatments.

Rapid, reliable and easy-to-perform chemometric-less method for rice syrup adulterated honey detection using FTIR-ATR.

The adulteration of honey (Apis mellifera) is a global problem due to its economic, commercial and health implications. The world's leading beekeeping organisation, APIMONDIA, considers that the detection of adulteration in honey is a problem that has not yet been resolved. This evidence of the importance of the intensive development of analytical techniques that allow the unequivocal detection of adulterants in honey, especially those whose use as honey adulterants has recently emerged. This work aims to develop a fast, easy-to-perform, low-cost analytical method to qualitatively and quantitatively determine rice syrup using the Fourier transform infrared spectroscopy (FTIR) technique with attenuated total reflectance (ATR) mode without complex mathematical procedures and sophisticated sample preparation. This study involved the analysis of 256 intentionally rice-syrup-adulterated honey samples and 92 pure honey samples of bee multifloral honey from Spain. The method, based strictly on the determination of the absorbance directly from the samples, at 1013 cm-1 The methodology used no need for previous treatments or preparations and demonstrated the scope for the unequivocal detection of rice syrup in adulterated honey containing equal to or higher than 3% (m/m) or more of this adulterant. Using the Exponential Plus Linear model (r = 0.998) shows high accuracy and precision, in terms of relative error (0.32%, m/m) and coefficient of variation (1.4%). The results of this study have led to the establishment of a maximum absorbance threshold of 0.670 for honey without rice syrup.

Functional properties of syrup from malted and unmalted rice of different varieties: A comparative study.

The continued increase in Nigeria's rice production makes product diversification very fitting, even to underutilized indigenous/local varieties. Further, rice converted to malt can bring about useful products like syrup with enhanced characteristics. In this context, a comparative study involving some functional properties of syrup from malted and unmalted rice of different varieties was carried out. Syrup from either filtered or centrifuged starch hydrolysates of enzyme hydrolyzed rice (malted/unmalted) flours gave rise to filtered unmalted (FUHR), filtered malted (FMHR), centrifuged unmalted (CUHR), and centrifuged malted hydrolyzed rice (CMHR) groups. From these, functional properties, that is, pH, total soluble proteins (TSP), total dissolved solids (TDS), total solids (TS), dextrose equivalent (DE), titratable acidity (TA), apparent brix (°B), specific gravity (SG), syrup yield (SY), and some minerals [calcium (Ca), iron (Fe), magnesium (Mg), and zinc (Zn)] were determined. Results showed syrup from malted with significantly higher (P < 0.05) SY, Brix, pH, SG, TS, TDS, and TSP, but significantly lower (P < 0.05) TA, DE, and mineral contents (Ca, Zn, Fe, and Mg) over the unmalted group. Some significant interactions (P < 0.05) were found, between rice variety, treatment and separation method (TS, TDS, DE, Brix, SY, and Ca), rice variety and treatment (TSP, Zn, Mg, and Fe), as well as rice variety and separation method (TSP, pH). In addition, some positive and negative significant (P < 0.05) correlations between the studied functional properties were found. Overall, malting and processing methods can influence the functional properties of rice syrup-an acceptable specialty ingredient for brewing/beverage production. PRACTICAL APPLICATION: Through the application of exogenous enzymes, rice syrup has been successfully produced from locally bred/improved rice varieties commercially available in Nigeria. By comparing some functional properties of syrup from malted and/or unmalted rice, the current research provides useful evidence that locally available rice varieties are potential candidates for product diversification to the food/brewing, pharmaceuticals, and other industries, not only in Nigeria but also in the West Africa subregion.

Low risk of category misdiagnosis of rice syrup adulteration in three botanical origin honey by ATR-FTIR and general model.

This study is about the rice syrup adulteration determination in different botanical origin honey in the food product. Due to time-consuming and large risk of misdiagnosis, it is essential to establish a general model for adulteration detection regardless of the original category of honey. In this paper, infrared (IR) spectra combined with four supervised pattern recognition methods were employed to establish the general model for rice syrup adulteration detection in acacia, linden and jujube honey samples simultaneously. Moreover, Monte-Carlo sampling technology was executed to evaluate the models via the average accuracy, sensitivity and specificity. The first derivative-least squares support vector machines (Der-LS-SVM) gave an outstanding performance with higher accuracy (97.09%), higher sensitivity (96.64%), higher specificity (97.58%) and lower standard deviations after fifty trials. In addition, this study makes further efforts to control the quality of the honey product in the market on rice syrup adulteration.

Determination of rice syrup adulterant concentration in honey using three-dimensional fluorescence spectra and multivariate calibrations.

To rapidly and efficiently detect the presence of adulterants in honey, three-dimensional fluorescence spectroscopy (3DFS) technique was employed with the help of multivariate calibration. The data of 3D fluorescence spectra were compressed using characteristic extraction and the principal component analysis (PCA). Then, partial least squares (PLS) and back propagation neural network (BP-ANN) algorithms were used for modeling. The model was optimized by cross validation, and its performance was evaluated according to root mean square error of prediction (RMSEP) and correlation coefficient (R) in prediction set. The results showed that BP-ANN model was superior to PLS models, and the optimum prediction results of the mixed group (sunflower±longan±buckwheat±rape) model were achieved as follow: RMSEP=0.0235 and R=0.9787 in the prediction set. The study demonstrated that the 3D fluorescence spectroscopy technique combined with multivariate calibration has high potential in rapid, nondestructive, and accurate quantitative analysis of honey adulteration.