College of Engineering and Technology, Southwest University, Chongqing, China.
Chongqing Key Laboratory of Agricultural Equipment in Hilly Area, Chongqing, China.
J Food Sci. 2024 Oct;89(10):6157-6173. doi: 10.1111/1750-3841.17303. Epub 2024 Aug 27.
The walnut cracking process is the most critical and delicate step for achieving high-quality kernels. The traditional method for cracking (manually) is labor-intensive, time-consuming, and tedious. The existing cracking approaches are low production efficiency and serious walnut kernel breakage. Increasing cracking efficiency with minimum kernel breakage has been a challenging issue in the preliminary processing of walnuts. Therefore, this study develops an innovative walnut cracker with self-grading and multi-station extrusion, combined with theoretical investigation and experiment verification. First, a statistical analysis of walnut physical properties was conducted, including dimensions, shell thickness as well as shape characteristics. The mechanical properties of walnut cracking were examined by a series of experiments. Based on mechanical theory, a grading mechanism was designed for preliminary processing before walnut cracking. Then a shaftless screw conveying mechanism and an extrusion cracking mechanism were developed. To evaluate the cracker's performance, a comprehensive examination was carried out. The experiments yielded impressive results, with a grading rate of 87.3%, a shell-breaking rate of 91.50%, and a kernel-exposed rate of 84.72%. These outcomes signify a substantial improvement in production efficiency while minimizing kernel breakage. The developed walnut cracker plays a crucial role in walnut processing and kernel extraction, thereby elevating economic value. PRACTICAL APPLICATION: A self-grading multi-station extrusion walnut cracker is developed, which includes a grading mechanism with a shaftless screw conveyor and a grid-type trommel screen for conveying and classifying walnuts. This cracker can adapt to different walnut varieties by changing the gap-adjusting guide to control the breaking gap. Compared to similar extrusion-type walnut crackers, the developed cracker not only incorporates preliminary classification but also exhibits superior performance. HIGHLIGHTS: A novel multi-station extrusion mechanism for walnuts cracking is developed. The cracker can accommodate various walnut sizes for self-grading and screening. The design with semi-arc plates converts extrusion force into alternating stress. The shell-breaking rate and kernel-exposed rate achieves 91.50% and 84.72%.
核桃的开裂过程是获得高品质果仁的最关键和最精细的步骤。传统的开裂方法（手工）劳动强度大、耗时且繁琐。现有的开裂方法存在生产效率低和严重的核桃仁破碎的问题。在核桃的初步加工中，以最小的果仁破碎率提高开裂效率一直是一个具有挑战性的问题。因此，本研究开发了一种具有自动分级和多工位挤压功能的创新型核桃开壳机，结合理论研究和实验验证。首先，对核桃的物理特性进行了统计分析，包括尺寸、壳厚以及形状特征。通过一系列实验研究了核桃的机械开裂特性。基于机械理论，设计了核桃开裂前的分级机构。然后开发了无轴螺旋输送机构和挤压开裂机构。为了评估开壳机的性能，进行了全面的检查。实验结果令人印象深刻，分级率为 87.3%，壳破碎率为 91.50%，仁暴露率为 84.72%。这些结果表明，在最小化果仁破碎率的同时，生产效率得到了显著提高。所开发的核桃开壳机在核桃加工和仁提取中起着至关重要的作用，从而提高了经济价值。实际应用：开发了一种自动分级多工位挤压核桃开壳机，包括无轴螺旋输送机构和网格式转筒筛的分级机构，用于输送和分类核桃。通过改变间隙调节导板来控制破碎间隙，该开壳机可以适应不同的核桃品种。与类似的挤压式核桃开壳机相比，所开发的开壳机不仅具有初步分类功能，而且性能更优。亮点：开发了一种用于核桃开裂的新型多工位挤压机构。该开壳机能适应各种核桃尺寸进行自动分级和筛选。半弧形板的设计将挤压力转化为交变应力。壳破碎率和仁暴露率分别达到 91.50%和 84.72%。
