Validation of rubric-based evaluation for bachelor's theses in a food science and technology degree.

An effective evaluation of a bachelor's thesis (BT) needs the use of valid tools such as rubrics. There are few studies providing a validation of rubrics for these theses and even fewer in the academic field of food science and technology; hence the aim of this study was to validate a rubric for the assessment of relevant competencies in the BT. Ninety-seven students presented their thesis and 56 teachers participated as members of the committees. The degree of relevance, suitability, and clarity of the rubrics were assessed as well as the relationship between student perception and academic performance and the congruence between the teacher's and students' evaluations. The content validity index and intraclass correlation coefficient (ICC) were calculated. Students had a moderate level of knowledge about rubrics, but they mostly agreed with the premise that the rubrics are an accurate tool to assess the quality of BTs. Teacher's and student's marks mostly aligned. No significant relationship was found between the positive perception of rubric's validity and the final grades. Regarding clarity, suitability, and relevance as perceived by teachers, the used rubrics were highly valued. The ICC of criteria indicated that the rubrics were valid in the studied terms. Hence, the validation of a food science and technology degree BT assessment system based on a rubric has been achieved. Supporting Information PRACTICAL APPLICATION: The conclusions drawn from this research could enable teachers at other universities to use this methodology for validating their rubrics for bachelor's theses. Furthermore, they could use this validated rubric to evaluate projects presented at their respective institutions.

Antioxidant peptides (<3 kDa) identified on hard cow milk cheese with rennet from different origin.

The effect of the addition of rennet from different origin (animal, plant and microbial) on the release of potential antioxidant peptides was evaluated in hard cow milk cheese. After cheese making, chemical parameters, colour, TBARs and riboflavin content were determined in the final product. Antioxidant activity of the water soluble extracts from cheese was evaluated by the DPPH radical scavenging and metal chelating activity assays. Separation of peptide fractions (<3 kDa) was performed by RP-HPLC and fractions with potential antioxidant activity were analyzed by LC-MS/MS for further identification of peptides. Results suggested that colour and riboflavin content were affected by the type of rennet used (P < .05). On the other hand, extracts of cheese with microbial rennet showed the highest antioxidant activity (P < .05). Only nine fractions isolated from the extracts showed either DPPH radical scavenging or metal chelating activities. Peptides EIVPN and DKIHPF, previously reported in other studies by showing ACE-inhibitory activity, were identified in these fractions and revealed high metal chelating activity. Moreover, a new peptide, with also high metal chelating activity, has been identified (VAPFPQ). In conclusion, it would be worthwhile to synthesis these peptides and confirm their antioxidant and metal chelating activities.

Effect of ripening time and rearing system on amino acid-related flavour compounds of Iberian ham.

The evolution of free amino acids and amino acid-derived volatile compounds during the ripening of Iberian ham from pigs reared in a Montanera system (outdoor-based, with acorn and pasture available) and a Pienso system (indoor-based, with a high oleic acid concentrate) was studied. Ripening time influenced significantly all the free amino acids detected (p<0.05) except for threonine and tyrosine. The total free amino acid content increased significantly from day 120 to day 230 (drying stage) and then the concentration remained almost steady. This marked increase in the free amino acid content matched an increase in the amino acid-derived volatile compounds. The volatile compounds also increased after day 230. Conversely, rearing system had a weak effect on the free amino acid content and on the amino acid-derived volatile compounds. Only glutamic acid was significantly influenced (p=0.027), and a slight effect on proline and aspartic acid was found (p=0.051 and p=0.084, respectively), concentrations being larger in Montanera hams than in Pienso ones. With regard to the amino acid derived volatile compounds, only a significant influence of rearing system on acetaldehyde and on the coelution of 2,6-dimethylpyrazine+dihidro-2(3H)furanone was found. The small differences caused by rearing system confirm the great importance of concentrate formulation.

Odor-active compounds of Iberian hams with different aroma characteristics.

The odor-active compounds of different commercial types of Iberian hams (Montanera and Pienso) were researched by gas chromatography-olfactometry based on a detection frequency method. The hams (long- and short-Montanera and Pienso Iberian hams) showed different sensory profiles, differences being significant for Montanera ham typical odor, aroma intensity and persistence, and cured and moldy aroma. Significant differences were also found for some odorants. The largest differences appeared in 2-acetyl-1-pyrroline, hexanal, (Z)-3-hexenal, ethyl 2-methylbutyrate, (E)-2-hexenal, 1-octen-3-one, 1-octen-3-ol, 2-propionyl-1-pyrroline, octanal, and an unknown odorant. Sensory characteristics and olfactometric profiles were significantly different between Montanera and Pienso hams. Significant differences also appeared between long- and short-Montanera hams, which shows great variability in this commercial type. Otherwise, the largest scores for moldy aroma in long-Montanera hams matched with the largest detection frequency of 1-octen-3-one and 1-octen-3-ol in this group.