Measurements of Chemical Compositions in Corn Stover and Wheat Straw by Near-Infrared Reflectance Spectroscopy

Application of near-infrared spectroscopy for hay evaluation at different degrees of sample preparation

OBJECTIVE

A study was conducted to quantify the performance differences of the nearinfrared spectroscopy (NIRS) calibration models developed with different degrees of hay sample preparations.

METHODS

A total of 227 imported alfalfa (Medicago sativa L.) and another 360 imported timothy (Phleum pratense L.) hay samples were used to develop calibration models for nutrient value parameters such as moisture, neutral detergent fiber, acid detergent fiber, crude protein, and in vitro dry matter digestibility. Spectral data of hay samples prepared by milling into 1-mm particle size or unground were separately regressed against the wet chemistry results of the abovementioned parameters.

RESULTS

The performance of the developed NIRS calibration models was evaluated based on R2, standard error, and ratio percentage deviation (RPD). The models developed with ground hay were more robust and accurate than those with unground hay based on calibration model performance indexes such as R2 (coefficient of determination), standard error, and RPD. Although the R2 of calibration models was mainly greater than 0.90 across the feed value indexes, the R2 of cross-validations was much lower. The R2 of cross-validation varies depending on feed value indexes, which ranged from 0.61 to 0.81 in alfalfa, and from 0.62 to 0.95 in timothy. Estimation of feed values in imported hay can be achievable by the calibrated NIRS. However, the NIRS calibration models must be improved by including a broader range of imported hay samples in the modeling.

CONCLUSION

Although the analysis accuracy of NIRS was substantially higher when calibration models were developed with ground samples, less sample preparation will be more advantageous for achieving rapid delivery of hay sample analysis results. Therefore, further research warrants investigating the level of sample preparations compromising analysis accuracy by NIRS.

Revealing mechanism of phenol-amine reaction to form humus in compost based on high-resolution liquid chromatography mass spectrometry and spectroscopy

Humus is the stable form of carbon storage in straw compost. The phenol-amine reaction is a pathway for humus formation in straw compost. In this study, two reaction systems, GP group (pyrogallol and glycine) and GCP group (catechol, pyrogallol, and glycine), were constructed in a simulated composting environment and revealed the molecular binding mechanism of the phenol-amine reaction through spectroscopy and mass spectrometry. The results showed that phenolic self-polymerization was faster than phenol-amine reaction. Therefore, the aromatization degree of GP was 27.14 % higher than that of GCP. The phenol-amine reaction first produced fulvic acid, and then formed humus units rich in active functional group structures (i.e., phenolic hydroxyl and carboxyl groups). These units further captured small molecule compounds to form humic acid eventually. This study would provide theoretical support for exploring the humus formation process and the promotion of straw humification by adding phenol or amino acids to compost.

Extrusion puffing as a pretreatment method to change the surface structure, physicochemical properties and in vitro protein digestibility of distillers dried grains with solubles

BACKGROUND

Distillers dried grains with solubles (DDGS) are rich in nutrition, and they are potential protein feed raw material. However, the existence of cellulose, hemicellulose and lignin hinders animals' digestion and absorption of DDGS. Making full use of unconventional feed resources such as DDGS can alleviate the shortage of feed resources to a certain extent. This research investigated the effects of twin-screw extrusion on the macromolecular composition, physical and chemical properties, surface structure and in vitro protein digestibility (IVPD) of DDGS.

RESULTS

The findings showed that extrusion puffing significantly increased the protein solubility, bulk density, water holding capacity, and swelling capacity, while significantly decreased hemicellulose and crude protein content, particle size and zeta potential of DDGS. The structure damage of DDGS induced by the extrusion was characterized by scanning electron microscopy (SEM), Fourier-transform infrared (FITR) spectroscopy and X-ray diffraction (XRD) analysis. Interestingly, no random coil was observed in the analysis of the secondary structure, and extrusion promoted the transformation of α-helix and β-turn to β-sheet, which led to significant increases in protein solubility and IVPD of DDGS (P < 0.05). Additionally, correlation analysis revealed that IVPD and PS had a positive relationship.

CONCLUSION

Extrusion puffing was an ideal pretreatment method for DDGS modification to improve in vitro protein digestibility. © 2023 Society of Chemical Industry.

Investigations on the Fusants From Wide Cross Between White-Rot Fungi and Saccharomyces cerevisiae Reveal Unknown Lignin Degradation Mechanism

The degradation of lignocellulose by fungi, especially white-rot fungi, contributes a lot to carbon cycle, bio-fuel production, and many other bio-based applications. However, the existing enzymatic and non-enzymatic degradation mechanisms cannot be unequivocally supported by in vitro simulation experiment, meaning that additional mechanisms might exist. Right now, it is still very difficult to discover new mechanisms with traditional forward genetic approaches. To disclose novel lignin degradation mechanisms in white-rot fungi, a series of fusants from wide cross by protoplast fusion between Pleurotus ostreatus, a well-known lignin-degrading fungus, and Saccharomyces cerevisiae, a well-known model organism unable to degrade lignocellulose, was investigated regarding their abilities to degrade lignin. By analyzing the activity of traditional lignin-degrading enzyme, the ability to utilize pure lignin compounds and degrade corn stalk, a fusant D1-P was screened out and proved not to contain well-recognized lignin-degrading enzyme genes by whole-genome sequencing. Further investigation with two-dimension nuclear magnetic resonance (NMR) shows that D1-P was found to be able to degrade the main lignin structure β-O-4 linkage, leading to reduced level of this structure like that of the wild-type strain P. ostreatus after a 30-day semi-solid fermentation. It was also found that D1-P shows a degradation preference to β-O-4 linkage in Aβ(S)-threo. Therefore, wide cross between white-rot fungi and S. cerevisiae provides a powerful tool to uncover novel lignocellulose degradation mechanism that will contribute to green utilization of lignocellulose to produce bio-fuel and related bio-based refinery.