Influence of grinding on the preservation of starch grains from rice

W Li,L Yao,C Tsoraki,J R Pagán‐Jiménez,A Van Gijn

doi:10.1111/arcm.12510

Abstract

China is a major centre for rice domestication, where starch grain analysis has been widely applied to archaeological grinding tools to gain information about plant use by ancient Chinese societies. However, few rice starch grains have been identified to date. To understand this apparent scarcity of starch grains from rice, dry‐ and wet‐grinding experiments with stone tools were carried out on four types of cereals: rice (Oryza sativa L.), foxtail millet (Setaria italica), Job's tears (Coix lacryma‐jobi L.) and barley (Hordeum vulgare L.). The results reveal that dry‐grinding produces significant damage to starches to the point where they may be undetected in archaeological samples, while wet‐grinding causes only slight morphological changes to the starch grains. Moreover, rice starch grains have the most substantial alterations from dry‐grinding, possibly impeding their identification. These findings provide a possible means to explain the relative scarcity of rice starch grains recovered from archaeological grinding tools, which it is suggested was caused by the use of the dry‐grinding technique. Therefore, it is suggested that rice starch grains have been likely underrepresented in the archaeological record, and previous interpretations of starch analyses need to be reconsidered.

Highlights

Rice (Oryza spp.) is an important crop in Asia, where cooking techniques, eating habits and feasting rituals have been historically associated with this plant (Cheung and Tan 2007)
China has three major regions that are currently considered the earliest centres for rice domestication, which include the lower catchment of the Yangtze River
Among the different grinding techniques, dry-grinding causes significant morphological changes to starch grains and affects starch grain detection, especially in the case of rice. This result suggests that the scarcity of rice starch grains recovered from grinding tools in Neolithic Chinese sites could be caused by the employment of the dry-grinding technique by ancient communities

Summary

Introduction

Rice (Oryza spp.) is an important crop in Asia, where cooking techniques, eating habits and feasting rituals have been historically associated with this plant (Cheung and Tan 2007). China has three major regions that are currently considered the earliest centres for rice domestication, which include the lower catchment of the Yangtze River (Liu et al 1981; Jiang and Liu 2006; Liu et al 2007; Trivers et al 2009), the middle catchment of the Yangtze River (e.g., Zhao 1998), and the upper catchment of the Huai River On the basis of the carried out research, these regions all possess well-documented evidence for rice domestication during the early Neolithic period (e.g., Lu et al 2002; Liu et al 2007; Zhao 2010; Wu et al 2014; Yang et al 2016a). Rice has been proven to have been used as an ingredient for fermented beverage production 9000 years BP at Jiahu (McGovern et al 2004)

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Discussion

Conclusion