2.2.5. Microstructure Determination

The microstructure and the surface characteristics of the pasta were studied with a Zeiss Sigma 300 VP (Carl Zeiss NTS GmbH, Oberkochen, Germany) field-emission gun scanning electron microscope (FEG-SEM) equipped with a secondary electrons detector (SE). The analyses were done under vacuum (<10−<sup>4</sup> Pa), using an accelerating voltage of 20 kV, an aperture of 30 μA, and a working distance between 4 and 5 mm and magnification of 1000×. Fragments of the different pasta samples were glued onto an aluminium stub with carbon tape. Before the analysis, all the samples were carbon-coated in order to make the surface of the specimen conductive.

### 2.2.6. Quantitative Descriptive Sensory Analysis

Sensory analyses were conducted by a panel of eight trained tasters (6 females and 2 males) to evaluate the sensory attributes according to Pasqualone et al. [35]. Pasta samples were coded by a three-digit number, cooked at their OCT, and evaluated for color, smell, taste, bulkiness, adhesiveness, hardness, and overall acceptability, using a structured scale ranging from 1 to 10. Color refers to the typical color of durum wheat pasta, where 1 = yellow color and 10 = brown; smell as perceived by olfaction and taste as perceived during mastication, which refer to the typical odor and taste of durum wheat pasta without anomalies, where 1 = very low and 10 = very high; bulkiness refers to adhesion of tagliatelle strands to each other, evaluated both visually and manually by pressing two tagliatelle together and determining the force required for detachment; stickiness, related to the organic matter released during cooking and still adhering to the surface of pasta, evaluated by pressing a single strand against the palate and determining the force require to remove it with the tongue; hardness, which is the resistance of cooked pasta to chewing measured while cutting the spaghetti strand using the front teeth. The analysis was carried out according to Pasqualone et al. [38], following the ethical guidelines of the Laboratory of Food Science and Technology of the Department of Plant, Soil, Food Science of University of Bari, Italy.
