ABSTRACT
Carasau bread is a flat bread, typical of Sardinia (Italy). The market of this food product has a large growth potential, and its industry is experiencing a revolution, characterized by digitalization and automation. To monitor the quality of this food product at different manufacturing stages, microwave sensors and devices could be a cost-effective solution. In this framework, knowledge of the microwave response of Carasau dough is required. Thus far, the analysis of the microwave response of Carasau doughs through dielectric spectroscopy has been limited to the dynamics of fermentation. In this work, we aim to perform complex dielectric permittivity measurements up to 8.5 GHz, investigating and modeling the role of water amount, salt and yeast concentrations on the spectra of this food product. A third-order Cole-Cole model was used to interpret the microwave response of the different samples, resulting in a maximum error of 1.58% and 1.60% for the real and imaginary parts of permittivity, respectively. Thermogravimetric analysis was also performed to support the microwave spectroscopy investigation. We found that dielectric properties of Carasau bread doughs strongly depend on the water content. The analysis highlighted that an increase in water quantity tends to increase the bounded water fraction at the expense of the free water fraction. In particular, the free water amount in the dough is not related to the broadening parameter γ2 of the second pole, whereas the bound water weight fraction is more evident in the γ2 and σdc parameters. An increase in electrical conductivity was observed for increasing water content. The microwave spectrum of the real part of the complex permittivity is slightly affected by composition, while large variation in the imaginary part of the complex dielectric permittivity can be identified, especially for frequencies below 4 GHz. The methodology and data proposed and reported in this work can be used to design a microwave sensor for retrieving the composition of Carasau bread doughs through their dielectric signature.
ABSTRACT
The aim of our study was to determine if the Sardinian folk dance ballu sardu (BS) can be identified as an effective workout regimen in terms of its exercise intensity (EI) and energy expenditure (EE) and if people who perform BS fulfill the recommendations of the American College of Sports Medicine on the prescription of exercise in healthy subjects. Twenty healthy volunteers (10 men, 10 women, 35.2 ± 6.3 years of age, BMI 23.0 ± 3.4 kg/m²) with BS experience (mean = 20.7 ± 8.9 years) were enrolled. All subjects underwent a maximal cardiopulmonary exercise test. Then they carried out a performance of about a quarter of an hour of BS in its most common variant of dance in a circle, ballu tundu. During the BS performance, the dancers wore a heart rate monitor to record all relevant data. The dancers displayed a good aerobic capacity (VO2max 44.1 ± 3.2 ml·kg(-1)·min(-1)). Their average HR during the BS execution was 146.3 ± 5.3 bpm, corresponding to an EI of 79.9% ± 6.5% of HRmax. The estimated average VO2 was 78.6% ± 15.4% of VO2max; MET/min and EE were 9.8 ± 1.5 and 11.2 ± 2.4 Kcal/min, respectively. It is concluded that the BS can be described as a vigorous physical activity. An ancient yet still widespread leisure activity embedded in the Sardinian culture, it meets some contemporary exercise recommendations for a healthy lifestyle.
