History

Catarina Tente,  Hugo Baptista, João Pedro Tereso, Margarida Cércio, João Luís Veloso, Cláudia Oliveira, Luís Seabra, Catarina Meira, Gabriel de Souza,
Tomás Cordero Ruiz, Manuel Luís Real

RESUMO
O sítio arqueológico da Senhora do Barrocal localiza-se no concelho de
Sátão, ocupando um dos rebordos da ribeira da Coja, afluente do Dão. Este é um território montanhoso cuja paisagem está dominada pelas formações rochosas graníticas. O povoado é de pequena dimensão e implanta-se numa elevação de tors graníticos. Foram aqui realizadas três campanhas de escavação arqueológica (2014 a 2016), cujos dados estão ainda em fase de estudo. Todavia, alguns dos resultados podem já ser abordados e os mesmos revelam a importância que este sítio
tem para a compreensão dos séculos X e XI na região beirã.
As escavações arqueológicas realizadas permitiram identificar espaços habitacionais e de armazenagem, uma estrutura defensiva em pedra e abundantes coleções de artefactos e de ecofactos. A mais impressionante (pela quantidade e variedade) é a carpológica. As sementes encontravam-se armazenadas num compartimento de uso doméstico, tendo-se conservado devido à sua carbonização ocorrida na sequência de um incêndio que afetou a totalidade do sítio. Estes
vestígios constituem uma das maiores coleções de sementes alto medievais portuguesas, o que permitirá avançar no conhecimento sobre as formas de exploração dos recursos por parte das comunidades rurais desta época. Também entre os vestígios arqueológicos se registaram a ocorrências de cerâmicas exógenas à região, o que é uma novidade neste tipo de povoados e cronologia. Há ainda elementos arquitectónicos que possibilitam a associação do povoado a um templo religioso, que terá sido erguido ou rededicado em 971.
O presente artigo é assim uma abordagem aos primeiros dados arqueológicos deste sítio de excepcional importância científica.

ABSTRACT
The archaeological site of Senhora do Barrocal (municipality of Sátão) is
located on the right bank of the Coja stream, a tributary of the River Dão, in a mountainous landscape characterized by granitic outcrops. This is a small settlement built on top of massive granitic tors. Three excavation seasons took place between 2014 and 2016. These are presently under study but already available results reveal the importance of this site
to the study of the 10th and 11th centuries in the Beira Alta region.
Indeed, the archaeological excavations allowed the identification of habitation and storage areas, a defensive structure built in stone, and abundant assemblages of artefacts and ecofacts. A large quantity and variety of seeds stand out among the latter. These were stored in a domestic facility and were preserved due to its carbonization during a fire that affected the whole site. This is one of the largest Early Medieval botanic assemblages in Portugal, thus providing crucial insights on the resource exploitation strategies undertaken by these rural communities.
Also, some imported pottery productions were found among the artefactual remains, which is an unexpected find in this type of settlements and time period. There are also architectonic remains showing a relation between Senhora do Barrocal and a nearby religious temple that may have been built in AD 971.
This contribution is therefore a first approach to the ongoing research on this scientifically exceptional archaeological site.

A new analytical approach based on high-performance liquid chromatography with diode array detector (HPLC-DAD) and multivariate data analysis was applied and assessed for analyzing the red dye extracted from cochineal insects, used in precious historical textiles. The most widely used method of analysis involves quantification of specific minor compounds (markers), using HPLC-DAD. However, variation in the cochineal markers concentration, use of aggressive dye extraction methods and poor resolution of HPLC chromatograms can compromise the identification of the precise insect species used in the textiles. In this study, a soft extraction method combined with a new dye recovery treatment was developed, capable of yielding HPLC chromatograms with good resolution, for the first time, for historical cochineal-dyed textiles. After principal components analysis (PCA) and mass spectrometry (MS), it was possible to identify the cochineal species used in these textiles, in contrast to the accepted method of analysis. In order to compare both methodologies, 7 cochineal species and 63 historical cochineal insect specimens were analyzed using the two approaches, and then compared with the results for 15 historical textiles in order to assess their applicability to real complex samples. The methodology developed here was shown to provide more accurate and consistent information than the traditional method. Almost all of the historical textiles were dyed with Porphyrophora sp. insects. These results emphasize the importance of adopting the proposed methodology for future research on cochineal (and related red dyes). Mild extraction methods and HPLC-DAD/MSn analysis yield distinctive profiles, which, in combination with a PCA reference database, are a powerful tool for identifying red insect dyes. Figure In pursuit of a precious red dye! A new methodology has been developed for determining the precise cochineal dye used in historical textiles. Mild extraction methods and HPLC-DAD yield distinctive profiles that, in combination with a dye reference database based on PCA, creates a powerful tool for identifying the precise red dye used. Surprisingly, almost all of the historical textiles analysed were not dyed with American cochineal.

Identification of American cochineal species (Dactylopius genus) can provide important information for the study of historical works of art, entomology, cosmetics, pharmaceuticals and foods. In this study, validated species of Dactylopius, including the domesticated cochineal D. coccus, were analysed by high-performance
liquid chromatography with a diode array detector (HPLC-DAD) and submitted to multivariate data analysis, in order to discriminate the species and hence construct a reference library for a wide range of applications. Principal components analysis (PCA) and partial least squares discriminant analysis (PLSDA)
models successfully provided accurate species classifications. This library was then applied to the identification of 72 historical insect specimens of unidentified species, mostly dating from the 19th
century, and belonging to the Economic Botany Collection, Royal Botanic Gardens, Kew, England. With this approach it was possible to identify anomalies in how insects were labelled historically, as several of them were revealed not to be cochineal. Nevertheless, more than 85% of the collection was determined to be species of Dactylopius and the majority of the specimens were identified as D. coccus. These results have shown that HPLC-DAD, in combination with suitable chemometric methods, is a powerful
approach for discriminating related cochineal species.

The colorant behaviour of cochineal and kermes insect dyes in 141 experimentally-dyed and 28 artificially-aged samples of silk and wool was investigated using ultra-high performance liquid chromatography coupled to photodiode array detector (UHPLC-PDA), liquid chromatography electrospray ionisation mass spectrometry (LC-ESI-MS) and image scanning electron microscopy – energy dispersive X-ray spectroscopy (SEM-EDX). Partial-least squares discriminant analysis (PLS-DA) was then used to model the acquired UHPLC-PDA data and assess the possibility of discriminating cochineal insect species, as well as their correspondent dyed and aged reference fibres. The resulting models helped to characterize a set of 117 red samples from 95 historical textiles, in which UHPLC-PDA analyses have reported the presence of cochineal and kermes insect dyes.

Analytical investigation of the experimentally-dyed and artificially-aged fibres has demonstrated that the ratio of compounds in the insects dye composition can change, depending on the dyeing conditions applied and the type of fibres used. Similarities were observed when comparing the UHPLC-MS and SEM-EDX results from the dyed and aged references with the historical samples. This was verified with PLS-DA models of the chromatographic data, facilitating the classification of the cochineal species present in the historical samples. The majority of these samples were identified to contain American cochineal, which is in agreement with historical and dye identification literature that describe the impact of this dyestuff into European and Asian dyeing practices, after the Iberian Expansion in the 16th century.

The analytical results emphasize the importance of using statistical data interpretation for the discrimination of cochineal dyes, besides qualitative and quantitative evaluation of chromatograms. Hence, the combination of UHPLC-PDA with a statistical classification method, such as PLS-DA, has been demonstrated to be an advisable approach in future investigations to assess closely related species of natural dyes in historical textile samples. This is particularly important when aiming to achieve more accurate interpretations about the history of works of art, or the application of natural dyes in old textile production.

Natural red dyes have long been associated with power and extravagance, asthey were always expensive to acquire and the dyeing process was complex and required highly specialized knowledge. Until the end of the 15th century, different species of Porphyrophora cochineal insects were collected and extensively traded throughout Europe and Asia. However, with the Iberian Expansion at the beginning of the 16th century, the Castilians began exporting American cochineal (Dactylopius coccus) from Mexico, which was richer in colorant than the European and Asian insects. The American dyestuff hence became a great success in European and Asian centres of textile production, and a lucrative commodity for the economy of the Castilian Empire throughout the colonial period. Using an interdisciplinary approach combining History and Chemistry, the current PhD project intends to take a closer look at the overall circulation of American cochineal as a commercial product as well as its dynamics in the ...

Recently, technological advances in the resolution of liquid chromatographic techniques, namely the conventional High Performance Liquid Chromatography (HPLC) used by Serrano et al. [1], led to an increasing separation performance, through the use of columns with smaller particle size package and lower flow rates allied to higher pressure and temperature conditions. Such improvements brought by state of the art technology like Ultra high-Performance Liquid Chromatography (UPLC) hence provided more accurate separations of low molecular weight compounds and complex samples [2]. Dyestuffs from plant and animal origin usually possess complex mixtures of diverse compounds and minor compounds with low molecular weight and, for this reason, they require an efficient chromatographic separation when it comes to identify their presence in dye extracts belonging to valuable historical works of art, such as paintings or textiles. Consequently, a UPLC method was created and optimized for the cor...

Natural organic dyes from diverse species of plants and animals have been widely characterized in cultural heritage objects using high-performance liquid chromatography (HPLC). As these dyes generally comprise very complex and polar matrixes of compounds and minor compounds, namely flavonoids, anthraquinones or indigoids, with low molecular weight (circa 200-600 Da) and different and/or similar physicochemical properties [1], chromatographic resolution has become a major concern , especially when distinguishing closely related species of plants and animals [2-3]. A new ultra high-performance liquid chromatography (UHPLC) was optimized to characterize a wide range of natural dyes and build a spectral database for future dye identification. This optimized method was subsequently compared with a conventional HPLC method, which has been often applied in the identification of natural organic dyes present in cultural heritage objects [4]. The optimization of a UHPLC method, supported by f...