1. Introduction
Oats are a common miscellaneous grain crop providing good economic benefits and a high nutritional value [
1]. Oats have special harvesting characteristics. The maturation time of kernels on the same plant is not consistent, and mature kernels are prone to falling off. The moisture content of kernels and stems is high during harvest [
2]. The efficiency of their agricultural production has been improved by the introduction of mechanized harvesting. However, due to the limitations of mechanical operation, it inevitably causes a certain degree of damage to the grain. The threshing device is the key component of harvesting machinery, the core of which is the threshing drum [
3]. When the kernels are squeezed, impacted, and rubbed by the working parts, some of the removed kernels will present different degrees of mechanical damage, such as peeling, cracking, and crushing [
4]. The nutritional quality of damaged oats easily changes during storage, which affects the storage performance of oats and causes postharvest loss.
To date, a great deal of work has been conducted in two research areas: grain threshing damage and nutritional quality. In terms of threshing damage, the main focus is on damage mechanism analysis, experimental research, mechanical analysis, finite element simulation, and the discrete element method [
5,
6,
7,
8,
9]. Javad Khazaei et al. [
10] studied the physical damage to wheat seeds under successive impact loadings and found that the main influencing factor of wheat grain damage was high-speed threshing. Ronald W. Brass [
11] found that different parts of the corn kernel have different mechanical properties and withstand different levels of impact force, and they also studied the development of kernel rupture. Wang et al. [
12] conducted finite element analysis on the dynamic process of corn kernel impact damage using HyperMesh and LS-DYNA. Xu L et al. [
13] carried out a theoretical analysis and finite element simulation of rice kernels subjected to oblique impacts from threshing teeth. Xu T et al. [
14] used the discrete element method to model and verify soybean seed particles. The above studies focused on major grain crops such as rice, wheat, corn, and soybeans, while the studies on oats are relatively few. To examine nutritional quality, a large number of studies have been carried out on the composition content, processing technology, function, and extraction of functional components, and they have made breakthrough progress [
15,
16,
17,
18,
19,
20,
21].
In summary, the current research on oats with regard to threshing damage and nutritional quality falls into two separate research areas, but they are inextricably linked. During threshing, the threshing element has a high impact force on oat stalks and kernels, which easily causes the crushing and breaking of kernels and seriously affects the subsequent changes in their nutrient composition. Therefore, it is necessary to combine these two types of studies to comprehensively analyze the damage to oats caused by threshing and its effects on the oats’ nutrient composition, which is of great significance for reducing oat damage and ensuring oat quality.
Impacts are a major source of threshing damage [
22]. In this study, the LS-DYNA module of ANSYS Workbench was used to simulate the impact process between oats and threshed elements and to analyze the changes in the von Mises stress, contact force, energy, critical velocity, and damage characteristics. A threshing test was carried out, and damaged kernels were collected. The kernels were classified according to their different damage types. The differences in the nutrient composition and content in oats with different damage types were analyzed by means of near-infrared spectroscopy and physicochemical testing. The results provide a theoretical basis for optimizing oat threshing devices, reducing threshing damage, and ensuring high-quality oat production.
2. Materials and Methods
2.1. Materials and Equipment
The oat variety Pinyan No. 4 was selected as the test material from the Shenfeng experimental field of Shanxi Agricultural University, Taigu, Shanxi Province. Under the condition of a minimum loss rate, oats were harvested in time. The kernel moisture content measured in the experiment was 21.27%.
Test equipment: 5TQ-85 plot breeding thresher (Shanxi Agricultural University, Jinzhong, China), SZX-16 stereo microscope (Olympus, Tokyo, Japan), Starter Kit NIR hyperspectral imaging system (Headwall Photonics, Carlsbad, CA, USA), LP-1000 constant-temperature and -humidity box (Guangdong Hongzhan Technology Co., Ltd, Dongguan, China), WG9070BE electric drum drying oven (Tianjin Tonglixinda Instrument Factory, Tianjin, China), 756 UV–Vis spectrophotometer (Shanghai Spectrum Instruments Co., Ltd, Shanghai, China), KDY-9820 Kjeldahl nitrogen analyzer (Beijing Tongrunyuan Electromechanical Technology Co., Ltd, Beijing, China), LG-30g high-speed pulverizer (Baixin Pharmaceutical Machinery Co., Ltd, Wenzhou, China), HH-2 electronic thermostatic water bath (Suzhou Weier Experimental Supplies Co., Ltd, Suzhou, China), and 330H analytical balance (Shimadzu, Kyoto, Japan).
2.2. Test Methods
2.2.1. Oat Impact Simulation
(1) Physical parameters and three-dimensional oat model
We selected a good-sized, full, undamaged oat kernel. The side with the ventral furrow was deemed the front, and the reverse side was the back. The bigger end with hair was considered the top, and the other end was the bottom. The left and right sides of the oats were almost symmetrical. Three views were photographed with a stereo microscope, and the 3D model was constructed using Autodesk Maya 2024 software, as shown in
Figure 1.
(2) Establishment of the impact model
The oat model was saved in stl format and smoothed in the pre-processing software SpaceClaim 2021 R1. The nail-toothed drum is a common type of oat threshing device. It uses the strong impact of nail teeth on crops and rubbing within the threshing gap for threshing. It has a significant threshing effect on crops with uneven feeding and high moisture content. A threshing element nail tooth was created with a diameter of 12 mm and a length of 76 mm. In an actual threshing situation, the nail teeth hit the oats. In order to facilitate the analysis, in this paper, the nail tooth was fixed, and the oat was used as a moving body to reverse-simulate the impact process. We adjusted the oat impact surfaces so that the top, bottom, front, back, and left sides of the oats collided centripetally with the nail tooth, as shown in
Figure 2.
(3) Finite element simulation analysis
The impact model was imported into LS-DYNA, and the material property parameters of the oat kernel and nail tooth were defined by referring to the literature [
23,
24,
25], as shown in
Table 1. We then selected the mesh module; the size of the oat mesh cell was 0.25 mm, the size of the nail tooth mesh cell was 0.5 mm, and the mesh resolution was 4. The mesh division of the impact model is shown in
Figure 3. The oat kernel was considered a flexible body. The nail tooth was considered a rigid body, with rigid body constraints applied to it. Friction contact was modeled between the oat kernel and the nail tooth, and the friction coefficient was 0.4. With an increase in threshing speed, the impact of the threshing device on crops gradually increases, and the threshing rate increases, but the number of broken kernels also increases. Oat kernels are slender and easily broken by high impact [
26]. A lower threshing speed should be selected without affecting the threshing effect. After referring to the literature [
27,
28], we set the speed of the oat kernel to 12 m/s and customized the contact surface between the oat kernel and the nail tooth when changing the oat impact surface. The impact model was solved, and the changes in the von Mises stress, contact force, and energy during the impact process were analyzed dynamically. The critical velocities and damage characteristics of the oat kernel during impact on different surfaces were determined.
2.2.2. Classification of Oat Threshing Damage
The degree of damage to oat kernels differs due to the different structure and movement parameters of the threshing device. In this paper, the self-developed nail-toothed 5TQ-85 plot breeding thresher was used for threshing oat plants. Damaged kernels were collected after threshing. The characteristics of kernel damage were observed by means of a stereo microscope, and the kernel damage was classified according to the different damage types.
2.2.3. Analysis of Nutritional Components of Oats
The weight of each type of sample was 150 g. The classified kernel samples and the control group samples (undamaged kernels) were placed in a constant-temperature and -humidity chamber for artificial aging treatment to simulate the natural aging process of oats during storage. The temperature of the constant-temperature and -humidity chamber was set to 45 °C, the humidity was 90%, and the storage time was 7 days [
29]. After aging, the samples were dried in a drying oven at 35 °C for 2 h, and then each sample was tested by means of near-infrared spectroscopy. Each sample was tested 5 times, and the average spectrum of the 5 measurements was taken as the final spectrum. The measurement wavelength range was 900–1700 nm. Due to the large amount of noise at the edges of the range, the effective band of 950–1650 nm was selected. The starch content in the samples was detected by means of acid hydrolysis [
30], the protein content was detected by means of Kjeldahl nitrogen determination [
31], the fat content was detected by means of Soxhlet extraction [
32], and the total phenol content was detected by means of Folin–Ciocalteu colorimetry [
33].
3. Results and Analysis
3.1. Impact Simulation Results and Analysis
3.1.1. Dynamic Analysis of Impact Processes
The trends in the von Mises stress, contact force, and energy with time are similar when the top, bottom, front, back, and left sides of the oat kernel are impacted by the nail tooth. Taking the top side’s impact process as an example, the stress contour plot of the xoz cross-section of the kernel and the changes in the von Mises stress, contact force, and energy are shown in
Figure 4. The simulation time from 0 to 8.87 μs is the pre-impact stage, as shown in
Figure 4B. In this stage, there is no contact between the kernel and nail tooth, and the von Mises stress and contact force are 0. All the energy is stored in the oat kernel in the form of kinetic energy. The simulation time from 8.87 to 134.88 μs is the impact stage. Between 8.87 and 71.91 μs, the kernel comes into contact with the nail tooth [
Figure 4A(a)], leading to maximum deformation [
Figure 4A(b)]. The von Mises stress and contact force gradually increase. The von Mises stress is the largest at the center of the contact area, while it gradually decreases and diffuses outward in the neighboring area. The kernel’s kinetic energy is gradually transformed into internal energy. Due to the extrusion contact between the kernel and the nail tooth, part of the kernel’s kinetic energy is converted into contact energy. This is the stage in which kernel damage is produced. As shown in
Figure 4B,C, between 71.91 and 134.88 μs, the kernel bounces back, moves in the opposite direction, and gradually detaches from the nail tooth. The stress and contact force are gradually reduced, and the kernel’s internal energy is gradually transformed into kinetic energy. As the extrusion between the kernel and the nail tooth decreases, the kernel’s contact energy gradually decreases. From 134.88 to 180 μs, the contact force is 0 after the kernel completely leaves the nail tooth; however, a small amount of stress still remains inside the kernel, which propagates inside the grain in the form of stress waves and gradually decays, as shown in
Figure 4A(c).
3.1.2. Mechanical Parameter Changes and Critical Velocity Determination
The maximum contact force values during impact at an impact velocity of 12 m/s are shown in
Figure 5. The highest maximum contact force is 38.37 N when the back of the kernel is impacted, followed by the values for a left-side impact and front impact, which are 35.19 N and 34.29 N, respectively. The maximum contact forces during a top impact and bottom impact are small, at 25.09 N and 18.57 N, respectively.
The maximum von Mises stress values during impact are shown in
Figure 6. The maximum von Mises stress contour plots of the xoz section of the kernel during impact are shown in
Figure 7. The red arrows in
Figure 7 indicate the direction of oat movement. When the kernel bottom is impacted, the maximum von Mises stress value is the highest, at 10.46 MPa. The second highest value is from a top impact, at 10.05 Mpa. The stress value is the largest at the center of the contact area, while it gradually decreases and diffuses outward in the neighboring area. When the front and back are impacted, the maximum von Mises stress values are 8.60 and 9.28 Mpa, respectively. The stress value is greatest at the center of the contact area. Due to the bending deformation of the kernel during impact, the side opposite the contact area is subjected to high tensile stresses. The stress value gradually decreases near the two ends. When the left side is impacted, the maximum von Mises stress value is the smallest, at 8.49 Mpa, and the stress distribution is similar to that of a front impact.
Compared with a top or bottom impact, the force on the kernel is more uniform and the contact area is larger when the kernel is impacted on the front, back, or left side, resulting in a smaller stress peak.
The maximum von Mises stress values at different impact velocities (9, 10, 11, 12, 13 m/s) are shown in
Figure 8. With an increase in impact velocity, the stress inside the oat gradually increases. Correlation analysis shows that the maximum von Mises stress is extremely significantly correlated with the velocity. When the collision velocity is large enough that the maximum stress exceeds the strength limit of the oat, cracking or fracture of the kernel occurs. The velocity at this point is the critical velocity for impact damage.
During a top impact, when the impact velocity reaches 13.38 m/s, the kernel is slightly damaged at the edge of the stress concentration area, as shown in
Figure 9a. During a bottom impact, when the collision speed reaches 13.10 m/s, the contact end exhibits breakage, as shown in
Figure 9b. The critical velocities of front, back, and left impacts are 13.40, 14.64, and 16.00 m/s, respectively. The damage characteristics of the three impact schemes are similar. When the kernel deformation is at its maximum, the side opposite the contact area is the first to rupture due to tensile stresses. The crack spreads along the direction of the kernel impact and ultimately penetrates the whole kernel, causing the kernel to fracture transversely and be broken into two pieces, as shown in
Figure 9c–h.
3.2. Classification of Oat Damage during Threshing
The damage to oats that occurs during threshing includes external damage and internal damage. External damage includes crushing and breaking, while internal damage mainly occurs in the form of stress cracks [
34]. Through observation, it was found that the forms of kernel threshing damage are various and complex but can be classified into four typical types according to their proportions: transverse fracture (X
1), bottom breakage (X
2), side fracture (X
3), and back crack (X
4), as shown in
Figure 10. The characteristics of threshing damage are consistent with the simulation results.
3.3. Changes in the Nutritional Components of Oats with Different Damage Types
Undamaged kernels (X
0) were set as the control group. The near-infrared spectra of five samples after pretreatment (second-order derivatives) are shown in
Figure 11. It can be seen from the spectra that the five samples had similar characteristic peaks, so the chemical compositions of oat kernels with different damage types were basically the same.
The results of starch, protein, fat, and total phenol content determination for the five samples are shown in
Table 2. The content of each nutritional component in undamaged kernels was the highest. The starch content of undamaged kernels was 55.90%. There were no significant differences among the different damage types in terms of the starch content, which ranged from 55.00% to 56.00%.
The protein content of undamaged kernels was 20.48%; this was followed by the kernels with bottom breakage and a back crack, with contents of 20.46% and 20.24%, respectively. The protein contents of these three samples were significantly higher than those of the other two samples. The lowest protein content (19.22%) was found in transversely fractured kernels.
The fat content of undamaged grains was 52.77 mg/g; this was followed by the kernels with a back crack and side fracture, with contents of 51.96 and 51.53 mg/g, respectively. The fat content of transversely fractured kernels was the lowest, at 44.78 mg/g—15.14% lower than that of undamaged kernels.
The total phenol content of undamaged kernels was 2.79 mg/g, which was significantly higher than that of damaged kernels. The total phenol contents of kernels with a side fracture and back crack were 2.38 and 2.37 mg/g, respectively. The total phenol content of the kernels with bottom breakage was the lowest, only 1.91 mg/g, and was significantly lower than that of other samples.
There were differences in the nutrient contents of oat kernels with different damage types. As shown in
Table 2, the component with the largest variation was total phenols, with variation as high as 13.18%. The coefficient of variation of fat was also relatively high, at 6.79%. This indicates that mechanical damage caused a great difference in the contents of these two components. The coefficient of variation of protein was 2.58%, and the coefficient of variation of starch was the lowest, at only 0.53%. This shows that the stability of the starch content is relatively high.
4. Discussion
4.1. Formation of Oat Threshing Damage
As with engineered materials, the mechanical damage and fracturing of grain kernels occur through a process. In this study, oat materials were regarded as isotropic, and kernel damage tended to occur first in the parts with higher stress. In fact, the inhomogeneity of oat grain tissue, the moisture content, the weak binding force of starch granules, and internal and external defects are also the main causes of kernel damage. After being subjected to external forces, some parts of the kernel are always destroyed first and form the source of damage. Kernel breakage, crack formation, and fracture are the different development stages of damage sources. A fracture is a special form of internal damage and is also the ultimate form of damage. This is consistent with the research results in the literature [
35,
36].
4.2. Effect of Threshing Damage on Nutritional Components of Oats
An oat kernel is mainly composed of a cortex, endosperm, and embryo. The cortex is rich in minerals, vitamins, proteins, fats, crude fibers, and phenolic compounds. The endosperm is the main part of the oat grain, accounting for more than 80% of the whole kernel [
37], and is mainly composed of starch, protein, fat, and other substances. The embryo is mainly composed of fat and protein [
38]. The respiration rate of damaged kernels is increased and their starch content decreases due to hydrolysis under respiration. Due to the short time period used in the aging test, the change in starch content was not significant in the early stage of storage, which is consistent with the view of Liu [
39]. The higher the degree of seed damage, the higher the respiratory rate. As the most serious form of damage, a kernel fracture accelerates the decomposition rate of proteins and fats. At the same time, a kernel fracture increases the contact area between the grain and the air, and the oxidation rate of the oil is accelerated. Therefore, the protein and fat contents of the transversely fractured kernel samples were the lowest. Phenolic substances have poor stability and are mostly present in the oat seed coat and aleurone layer [
40]. In the test, the bottom breakage of kernels caused damage to and loss of the seed coat and aleurone layer, so the total phenol content of the samples with bottom damage was the lowest.
5. Conclusions
(1) The stresses and contact forces tended to increase and then decrease when the kernels were impacted. When the impact velocity was 12 m/s and the top, bottom, front, back, and left sides of the oat kernel impacted by the nail tooth, the maximum von Mises stresses were 10.05, 10.46, 8.60, 9.28, and 8.49 MPa, respectively. The maximum contact forces were 25.09, 18.57, 34.29, 38.37, and 35.19 N, respectively. The stress value was greatest at the center of the contact area.
(2) With an increase in impact velocity, the stress inside the oat gradually increased. When the top, bottom, front, back, and left sides of the oat kernel were impacted by the nail tooth, the critical velocities of impact damage were 13.38, 13.10, 13.40, 14.64, and 16.00 m/s, respectively. The contact surface was damaged when the top and bottom were impacted. When the front side, back side, and left side were impacted, the surface opposite the contact area cracked first under the action of tensile stress, and the crack spread along the impact direction of the kernel, eventually penetrating the whole kernel. In oat harvesting, when the threshing velocity exceeds the critical velocity, the damage and breakage of the kernels increase rapidly. In order to reduce oat damage, the velocity of the threshing drum should be less than the minimum critical velocity of oat impact damage. The simulation research results provide an important theoretical basis for the parameter design of oat threshing devices.
(3) After threshing, according to the different damage forms, kernel damage could be divided into four typical types: transverse fracture, bottom breakage, side fracture, and back crack.
(4) The chemical compositions of oat kernels with different damage types were basically the same, but their nutrient contents were different. The content of each nutritional component in the undamaged kernels was the highest. There were no significant differences in the starch content among the different damage types. The protein contents of the five samples followed the order undamaged kernels > bottom breakage > back crack > side fracture > transverse fracture. Mechanical damage caused great differences in the contents of fats and total phenols. The fat content of undamaged kernels was the highest, at 52.77 mg/g. The fat content of transversely fractured kernels was the lowest, at 44.78 mg/g—15.14% lower than that of undamaged kernels. The total phenol content of undamaged kernels was 2.79 mg/g, which was significantly higher than that of damaged kernels. The total phenol content of kernels with bottom breakage was the lowest, only 1.91 mg/g, and was significantly lower than that of other samples. Compared with undamaged kernels, the nutritional quality of damaged kernels decreased during storage, resulting in postharvest loss. In future research, the structure and parameters of the oat threshing device should be optimized to reduce oat damage and ensure oat quality. However, due to the limitations of mechanical operation, it inevitably causes some damage to oats. Partially damaged seeds can be used in animal feed for better economic benefit.
Author Contributions
Conceptualization, Y.L.; methodology, Y.L.; software, Y.L.; validation, Y.L. and D.Z.; formal analysis, P.X.; investigation, P.X. and J.S.; resources, D.Z.; data curation, J.S.; writing—original draft preparation, Y.L.; writing—review and editing, Y.L. and D.Z.; project administration, Y.L. All authors have read and agreed to the published version of the manuscript.
Funding
This research was funded by the Shanxi Province Basic Research Program (No. 202103021223146) and the Youth Science and Technology Innovation Project of Shanxi Agricultural University (No. 2020QC05).
Institutional Review Board Statement
Not applicable.
Data Availability Statement
All data supporting the findings of this study are available from the corresponding authors upon reasonable request.
Conflicts of Interest
The authors declare no conflicts of interest.
References
- Stern, V.; Zute, S.; Brunava, L. Oat grain composition and its nutrition benefice. Agric. Agric. Sci. 2016, 8, 252–256. [Google Scholar] [CrossRef]
- Geng, L.; Sun, C.; Zuo, J.; Jin, X.; Kong, L.; Ji, J. Design on oat-grains purification device with rubbing roller. Trans. Chin. Soc. Agric. Eng. 2019, 35, 38–47. [Google Scholar]
- Zhan, G.; Ma, L.; Huang, X.; Zong, W.; Tian, W.; Lin, Z. Experimental study on impact crushing of rapeseed stalks during threshing of oilseed rape. Trans. Chin. Soc. Agric. Eng. 2020, 36, 11–18. [Google Scholar]
- Li, H.; Zeng, R.; Yang, T.; Niu, Z. Experimental study on the impact breakage characteristics of maize kernels. Trans. Chin. Soc. Agric. Eng. 2022, 38, 29–37. [Google Scholar]
- Bolong, W.; Gao, M.; Geng, D.; Shi, Z. Study on Damage Mechanism and Crack Growth of the Corn Grain. J. Fail. Anal. Prev. 2022, 22, 1526–1534. [Google Scholar] [CrossRef]
- Shahbazi, F. Impact damage to chickpea seeds as affected by moisture content and impact velocity. Appl. Eng. Agric. 2011, 27, 771–775. [Google Scholar] [CrossRef]
- Xu, L.; Li, Y.; Ding, L. Contacting mechanics analysis during impact process between rice and threshing component. Trans. Chin. Soc. Agric. Eng. 2008, 24, 146–149. [Google Scholar]
- Baryeh, E.A. A simple grain impact damage assessment device for developing countries. J. Food. Eng. 2003, 56, 37–42. [Google Scholar] [CrossRef]
- Dun, G.; Li, H.; Yu, C.; Yang, Y.; Gao, Z.; Mao, N.; Zhang, S. Simulation collision analysis of soybean seed based on finite element method. J. Henan Agric. Univ. 2020, 54, 620–629. [Google Scholar]
- Khazaei, J.; Shahbazi, F.; Massah, J.; Nikravesh, M.; Kianmehr, M.H. Evaluation and modeling of physical and physiological damage to wheat seeds under successive impact loadings: Mathematical and neural networks modeling. Crop. Sci. 2008, 48, 1532–1544. [Google Scholar] [CrossRef]
- Brass, R.W.; Marley, S.J. Roller shelter: Low damage corn shelling cylinder. Trans. ASABE 1973, 16, 0064–0066. [Google Scholar] [CrossRef]
- Wang, B.; Wang, J.; Du, D. Finite element analysis of dynamic impact damage process of maize kernel based on HyperMesh and LS-DYNA. J. Zhejiang Univ. 2018, 44, 465–475. [Google Scholar]
- Xu, L.; Li, Y.; Ma, Z.; Zhao, Z.; Wang, C. Theoretical analysis and finite element simulation of a rice kernel obliquely impacted by a threshing tooth. Biosyst. Eng. 2013, 114, 146–156. [Google Scholar]
- Xu, T.; Yu, J.; Yu, Y.; Wang, Y. A modelling and verification approach for soybean seed particles using the discrete element method. Adv. Powder. Technol. 2018, 29, 3274–3290. [Google Scholar] [CrossRef]
- Getaneh, F.A.; Sirawdink, F.F.; Yetenayet, B.T.; Minbale, A.T.; Addisu, A.A.; Endale, A. Proximate, mineral and anti-nutrient compositions of oat grains (Avena sativa) cultivated in Ethiopia: Implications for nutrition and mineral bioavailability. Heliyon 2021, 7, e07722. [Google Scholar]
- Amanuel, W.; Kassa, S.; Deribe, G. Biomass yield and nutritional quality of different oat varieties (Avena sativa) grown under irrigation condition in Sodo Zuriya District, Wolaita Zone, Ethiopia. Agric. Res. Tech. 2019, 20, 556138. [Google Scholar]
- Ren, C.; Yan, J.; Dong, R.; Hu, X. Research Progress on Oat Nutrients, Functional Properties and Related Products. Sci. Technol. Food. Ind. 2022, 43, 438–446. [Google Scholar]
- Decker, E.A.; Rose, D.J.; Stewart, D. Processing of oats and the impact of processing operations on nutrition and health benefits. Br. J. Nutr. 2014, 112, S58–S64. [Google Scholar] [CrossRef] [PubMed]
- Beck, E.J.; Tosh, S.M.; Batterham, M.J.; Tapsell, L.C.; Huang, X.F. Oat beta-glucan increases postprandial cholecystokinin levels, decreases insulin response and extends subjective satiety in overweight subjects. Mol. Nutr. Food Res. 2009, 53, 1343–1351. [Google Scholar] [CrossRef]
- Zhang, K.; Dong, R.; Hu, X.; Ren, C.; Li, Y. Oat-based foods: Chemical constituents, glycemic index, and the effect of processing. Foods 2021, 10, 1304. [Google Scholar] [CrossRef]
- Hossain, M.M.; Tovar, J.; Cloetens, L.; Florido, M.T.S.; Petersson, K.; Prothon, F.; Nilsson, A. Oat polar lipids improve cardiometabolic-related markers after breakfast and a subsequent standardized lunch: A randomized crossover study in healthy young adults. Nutrients 2021, 13, 988. [Google Scholar] [CrossRef] [PubMed]
- Xu, L.; Li, Y.; Wang, X. Research development of grain damage during threshing. Trans. Chin. Soc. Agric. Eng. 2009, 25, 303–307. [Google Scholar]
- Wei, L.; Han, Z.; Dai, F.; Li, X.; Gao, A.; Zhang, K. Finite element analysis on the mechanical properties of breeding wheat grain. Acta Agric. Zhejiangensis 2016, 28, 378–382. [Google Scholar]
- Wang, J. Design and Research of Inner and Outer Roller Rotary Buckwheat Threshing Device. Ph.D. Thesis, Shanxi Agricultural University, Jinzhong, China, 2023. [Google Scholar]
- Sun, J. Study on Biomechanical Properties and Damage Mechanism of Coarse Cereals Crains. Ph.D. Thesis, Shanxi Agricultural University, Jinzhong, China, 2020. [Google Scholar]
- Geng, L.; Zuo, J.; Sun, C.; Lu, F.; Wang, S. Experimental study on horizontal section axial flow oat separator. J. Agric. Mech. Res. 2020, 44, 137–143. [Google Scholar]
- Lu, Q.; Zheng, D.; Li, L.; Liu, Y. Design and experiment of 5TG-85 buckwheat thresher. INMATEH Agric. Eng. 2022, 66, 289–300. [Google Scholar] [CrossRef]
- Cheng, F. The Design and Research of Grain Thresher Machine in Grain Crop Area. Master’s Thesis, Shanxi Agricultural University, Jinzhong, China, 2021. [Google Scholar]
- Song, X.; Ou, Q.; Zheng, J.; Gan, Y.; Wu, Z.; Shi, Y.; Liu, G. Study of artificial aged rape seeds by infrared spectroscopy. Seed 2023, 42, 149–156. [Google Scholar]
- Determination of Starch in Foods. Available online: https://img59.chem17.com/1/20170726/636366583857616209893.pdf (accessed on 23 December 2016).
- Determination of Protein in Foods. Available online: https://www.antpedia.com/standard/pdf/1/1901/GB%205009.5-2016.pdf (accessed on 23 December 2016).
- Determination of Fat in Foods. Available online: https://www.anan.gov.cn/anan/cpbz/201801/ffddf722c4e44dcb9888d7e1b55c0146/files/163c21654559468aad3b88f429f07498.pdf (accessed on 23 December 2016).
- Cheng, Z.; Guo, H.; Hu, J.; He, Y.; Li, H.; Li, Y. Relationship between chlorophyll, total phenol, PPO and browning of dehulled common buckwheat seeds. J. Chin. Cereals Oils Assoc. 2020, 35, 19–25. [Google Scholar]
- Xu, L.; Li, Y.; Qang, X. Quantification and detection methods of rice threshing damage. Trans. Chin. Soc. Agric. Mach. 2007, 11, 185–188. [Google Scholar]
- Li, L. Effects of Mechanical Threshing Damage on Grain Storage Quality Traits. Master’s Thesis, Nanjing Agricultural University, Nanjing, China, 2020. [Google Scholar]
- Wang, X.; Li, Y.; Xu, L. Mechanical Injury Mechanism of Rice Grain and Experiments. J. Agric. Mech. Res. 2007, 12, 141–143+147. [Google Scholar]
- Zhang, H. Preparation and Properties of β-glucan. Master’s Thesis, Jiangnan University, Wuxi, China, 2023. [Google Scholar]
- Zhang, Z.; Tao, G.; Yi, S.; Mao, X. Compressive mechanical property test and crack formation law analysis of naked oats grain. J. Shenyang Univ. 2019, 50, 371–377. [Google Scholar]
- Liu, Y.; Ni, W.; Liu, Z.; Lv, Z.; Cui, P.; Pang, L.; Lu, G. Effects of sweet potato injury during storage on physiological characteristics and storage quality after callus. J. North China Agric. Sci. 2023, 38, 219–227. [Google Scholar]
- Wang, B.; Li, G.; Li, L.; Zhang, M.; Yang, T.; Xu, Z.; Qin, T. Novel processing strategies to enhance the bioaccessibility and bioavailability of functional components in wheat bran. Crit. Rev. Food Sci. Nutr. 2022, 64, 3044–3058. [Google Scholar] [CrossRef] [PubMed]
Figure 1.
Oat kernel and 3D model: (a) front view; (b) left view; (c) 3D model.
Figure 1.
Oat kernel and 3D model: (a) front view; (b) left view; (c) 3D model.
Figure 2.
A schematic diagram of the impact schemes between the oat kernel and nail tooth: (a) top; (b) bottom; (c) front; (d) back; (e) left.
Figure 2.
A schematic diagram of the impact schemes between the oat kernel and nail tooth: (a) top; (b) bottom; (c) front; (d) back; (e) left.
Figure 3.
Mesh dividing of impact models: (a) top; (b) bottom; (c) front; (d) back; (e) left.
Figure 3.
Mesh dividing of impact models: (a) top; (b) bottom; (c) front; (d) back; (e) left.
Figure 4.
The results of a dynamic simulation of the top side’s impact process: (A) stress contour plot; (B) von Mises stress and contact force; (C) energy changes.
Figure 4.
The results of a dynamic simulation of the top side’s impact process: (A) stress contour plot; (B) von Mises stress and contact force; (C) energy changes.
Figure 5.
Maximum contact force values.
Figure 5.
Maximum contact force values.
Figure 6.
Maximum von Mises stress values.
Figure 6.
Maximum von Mises stress values.
Figure 7.
Maximum von Mises stress contour plots: (a) top; (b) bottom; (c) front; (d) back; (e) left.
Figure 7.
Maximum von Mises stress contour plots: (a) top; (b) bottom; (c) front; (d) back; (e) left.
Figure 8.
Maximum von Mises stress values at different impact velocities. Note: R1, R2, R3, R4, and R5 indicate the correlation coefficients between stress and velocity during top, bottom, front, back, and left-side impacts, respectively; ** indicates extremely significant correlation (p < 0.01).
Figure 8.
Maximum von Mises stress values at different impact velocities. Note: R1, R2, R3, R4, and R5 indicate the correlation coefficients between stress and velocity during top, bottom, front, back, and left-side impacts, respectively; ** indicates extremely significant correlation (p < 0.01).
Figure 9.
Damage characteristics of oat kernels at critical velocity: (a) damage from a top impact; (b) damage from a bottom impact; (c) damage emergence from a front impact; (d) final damage from a front impact; (e) damage emerging from a back impact; (f) final damage from a back impact; (g) damage emerging from a left impact; (h) final damage from a left impact.
Figure 9.
Damage characteristics of oat kernels at critical velocity: (a) damage from a top impact; (b) damage from a bottom impact; (c) damage emergence from a front impact; (d) final damage from a front impact; (e) damage emerging from a back impact; (f) final damage from a back impact; (g) damage emerging from a left impact; (h) final damage from a left impact.
Figure 10.
Oat threshing damage types: (a) transverse fracture; (b) bottom breakage; (c) side fracture; (d) back crack.
Figure 10.
Oat threshing damage types: (a) transverse fracture; (b) bottom breakage; (c) side fracture; (d) back crack.
Figure 11.
Near-infrared spectra of samples after pretreatment.
Figure 11.
Near-infrared spectra of samples after pretreatment.
Table 1.
Material properties.
Table 1.
Material properties.
Mechanical Property Index | Modulus of Elasticity/Mpa | Ultimate Strength/Mpa | Poisson’s Ratio | Density/(g/cm3) |
---|
Oat | 135 | 11.68 | 0.4 | 1.335 |
Nail tooth | 206,000 | 295 | 0.28 | 7.85 |
Table 2.
Nutrient contents of oats with different damage types.
Table 2.
Nutrient contents of oats with different damage types.
Sample | Starch/% | Protein/% | Fat/(mg/g) | Total Phenols/(mg/g) |
---|
X0 | 55.90 ± 0.12 a | 20.48 ± 0.09 a | 52.77 ± 1.13 a | 2.79 ± 0.07 a |
X1 | 55.27 ± 0.08 a | 19.22 ± 0.14 b | 44.78 ± 1.73 b | 2.07 ± 0.07 c |
X2 | 55.45 ± 0.45 a | 20.46 ± 0.07 a | 46.33 ± 0.69 b | 1.91 ± 0.05 d |
X3 | 55.74 ± 0.33 a | 19.60 ± 0.20 b | 51.53 ± 0.69 a | 2.38 ± 8.40 × 10−4 b |
X4 | 55.59 ± 0.20 a | 20.24 ± 0.24 a | 51.96 ± 1.09 a | 2.37 ± 0.01 b |
Standard deviation | 0.29 | 0.52 | 3.36 | 0.30 |
Mean | 55.59 | 20.00 | 49.47 | 2.30 |
Coefficient of variation | 0.53% | 2.58% | 6.79% | 13.18% |
| Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. |
© 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).