Doctoral Dissertation Improvement: The Effects of Food Processing on Mechanical Properties and Masticatory (Chewing) Performance

加工食品是人类的普遍行为。然而，食物改性对人类生物学的影响知之甚少，大多数研究集中在热加工(烹饪)上，而非热、机械加工方法在很大程度上还没有被研究。为了解决这些理解上的差距，这项研究测试了简单的机械加工(敲打和切片)和烹饪(烘焙)对咀嚼(咀嚼)性能的影响。被检验的一般假设是，机械加工对食品材料特性的影响可能有助于解释在采用烹饪之前人属内牙齿尺寸的减小。为了验证这一假设，14名受试者将咀嚼标准大小的生食或加工食品样本。肌肉活动的肌电记录和相关的咬合力数据将从咀嚼肌肉中收集，并建立一个预测模型，用于确定机械加工是否可以解释旧石器时代中期之前牙齿大小的减少，届时考古学证据首次变得丰富。还将收集食物在口腔中分解的效率(每次咀嚼的食物碎片率)和关于食物机械特性的数据。智力优势-这项研究是第一批评估代表性食物的烹饪和机械加工如何影响咀嚼的关键生物力学特性的研究之一，如咀嚼次数、作用力和食物粉碎效率。在人类进化过程中，关于烹饪的争论一直很多，但这项研究在试验性地测试烘焙食品的咀嚼性能影响的同时，也测试了可能早于烹饪的其他潜在的重要食品加工形式，特别是机械嫩化和切片。更广泛的影响--这项研究促进了研究生教育，并将使女性研究生获得博士学位。此外，产生的数据将增加关于原始人饮食、食品机械特性、加工效果和咀嚼性能的知识。鉴于人们对烹饪和其他食品加工技术的兴趣，这些结果涉及到广泛的领域，包括人类学、食品科学、进化生物学和解剖学。

Processing food is a universal human behavior. The effects of food modification on hominin biology are poorly understood, however, and most research focuses on thermal processing (cooking), leaving non-thermal, mechanical processing methods largely unstudied. To address these gaps in understanding, this research tests the effects of simple mechanical processing (pounding and slicing) and cooking (roasting) on masticatory (chewing) performance. The general hypothesis tested is that the effects of mechanical processing on food material properties may help account for dental size reductions within the genus Homo prior to the adoption of cooking. To test this hypothesis, 14 subjects will chew size-standardized samples of raw or processed food. EMG (electromyographic) recordings of muscle activity and correlated bite-force data will be collected from masticatory muscles and a predictive model used to determine whether mechanical processing can account for tooth size decreases prior to the Middle Paleolithic, when archeological evidence for cooking first becomes abundant. The efficiency of food breakdown in the mouth (rate of food fragmentation per chew) and data on the foods' mechanical properties will also be collected. Intellectual merits- This study is among the first to assess how cooking and mechanical processing of representative foods affect key biomechanical properties of mastication such as chew number, force production and food fragmentation efficiency. There has been much debate concerning cooking in human evolution, but while this study experimentally tests the masticatory performance effects on roasted foods, it also tests other potentially important forms of food processing that probably predate cooking, notably mechanical tenderization and slicing. Broader Impacts- This research promotes graduate education and will result in a Ph.D. for a female graduate student. Additionally, the data generated will increase knowledge on hominin diets, food mechanical properties, processing effects and chewing performance. Given interest in cooking and other food processing techniques, the results are relevant to a wide variety of fields including anthropology, food science, evolutionary biology and anatomy.