Bay salt in seventeenth-century meat preservation: how ethnomicrobiology and experimental archaeology help us understand historical tastes

Authors: TSAI, GRACE - Texas A&M University; Anderson, Robin; Kotzur, Jacquline - Jackie; DAVILA, ERIKA - Texas A&M University; MCQUITTY, JOHN - Texas A&M University; NELSON, EMELIE - Texas A&M University

Submitted to: British Journal of Historical Science-Themes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/18/2022
Publication Date: 10/7/2022
Citation: Tsai, G.E., Anderson, R.C., Kotzur, J.M., Davila, E., Mcquitty, J., Nelson, E. 2022. Bay salt in seventeenth-century meat preservation: how ethnomicrobiology and experimental archaeology help us understand historical tastes. British Journal of Historical Science-Themes. 7:63-93. https://doi.org/10.1017/bjt.2022.7.
DOI: https://doi.org/10.1017/bjt.2022.7

Interpretive Summary: Food preservation technology prior to canning and refrigeration involved salting, fermenting, drying, or smoking foods with some technologies still being used for specialty meats today. Salting was one extensively used technology and numerous meats were heavily treated with it. Different types of salts were used for salting, with sea salt being made by boiling sea water over a fire to evaporate the salt to dryness, bay salt being made by evaporating sea water in earthen pits with sunlight, and rock salt being dug out of the ground. Each of these salts had different characteristics but for reasons not clearly known; bay salt was often more preferred for salting than the other salt types. Presently, we examined the antimicrobial and meat preserving activities of bay, sea, and rock salt when used according to historical meat salting processes. Results revealed that all salts contained high levels of nitrate, with amounts being about 1.5 times higher in bay and sea salt than rock salt. Microbiological analysis revealed Escherichia coli bacteria, often used as indicators of food- or waterborne pathogens, were below detectable amounts in all salts. High numbers (> 10,000 bacteria per gram) of salt-loving bacteria were recovered from the bay salt, whereas these salt-loving bacteria were undetectable in the sea and rock salt. The absence of the salt-loving bacteria in the sea salt was likely due to this salt being boiled to remove water during its preparation, whereas the absence of salt-loving bacteria in rock salt is because this salt had too low a water content to support microbial growth. Using molecular RNA-based techniques to characterize the different bacteria within the salt-loving population, we found that many, with some being newly discovered bacteria, were able to interconvert nitrate and nitrite. A comparison of the beginning and end nitrate concentrations of salted meat showed that nitrates increased in the meat over the course of the experiment. These increased nitrate levels were correlated with an increase in the salt-loving bacteria. These results suggest that bay salt’s advantage over the other salts was not solely economical or due to adherence to tradition, but because bay salt contains salt-loving bacteria able to produce nitrates which help to not only better preserve the microbiological quality of the meat, but its visual and eating quality as well. Ultimately, this research may help meat processors optimize techniques to better preserve certain types of meat at lower cost and better eating value for American consumers.

Technical Abstract: ‘Sea salt is made by boiling and evaporating sea water over the fire. Bay salt, by evaporating sea water, in pits clayed on the inside, by the heat of the sun. Basket salt is made by boiling away the water of salt springs over the fire. Rock salt is dug out of the ground […]’ wrote Charlotte Mason in The Lady's Assistant (1775), one of the most comprehensive 18th-century cookbooks. Although there were at least four variations of salt available prior to the pre-industrial era, several recipes, such as John Collins’ Salt and Fishery (1682), specified the use of bay salt (solar salt) for meat preservation, and elevated its cultural status. This suggests that early modern actors had a refined understanding of salts, their taste, and their applications. This study, a result of the Ship Biscuit and Salted Beef Research Project (SBSB), a project that aimed to determine the effects of 17th-century maritime diet on the nutrition and health of sailors during the Age of Sail, uses scientific analysis to determine if there is a biological or chemical basis to the superior reputation of bay salt in food preservation. Laboratory data suggest that rather than differences in mineral content, bay salt contains microbes that produce nitrate and nitrite, which lend a more favorable taste and pleasant aesthetic to the meat, along with antimicrobial properties. The authors thus demonstrate that combining insights from experimental archaeology with textual analysis of historical sources gives us a deeper understanding of historical uses of taste as an epistemic tool.