Banca de DEFESA: ALLANA SOBRINHO DOS SANTOS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ALLANA SOBRINHO DOS SANTOS
DATE: 13/12/2022
TIME: 08:30
LOCAL: Sala de seminários IQ
TITLE:

DEVELOPMENT OF DECOMPOSITION PROCEDURES IN CLOSED SYSTEMS FOR WHITE CHEESE ELEMENTAL ANALYSIS

KEY WORDS:

White cheese, Elemental analysis, Sample preparation, Closed digester block, microwave-assisted decomposition

PAGES: 80
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Analítica
SPECIALTY: Métodos Óticos de Análise
SUMMARY:

Cheese is the most consumed dairy product, its popularity is attributed to its taste, versatility of use, price, variety, and nutritional value. Recently, consumers have preferred white cheeses to yellow cheeses due to their low caloric content; however, studies on determining essential or potentially toxic elements are still scarce. Thus, the present work aims to evaluate decomposition procedures in closed systems with different forms of heating for elemental analysis in samples of white cheese by ICP OES. The optimization step was carried out using a two-level complete factorial design with an experimental domain for temperature between 140 and 180 ºC for both methods; and concentration of HNO3 2, 8, and 14 mol L-1 at 40, 60, and 80 min and 2, 6 and 8 mol L-1 for 20, 25 and 30 minutes, in closed digester block and microwave cavity, respectively. The dissolved organic carbon (DOC) content evaluated the decomposition efficiency. For both methods, the concentration parameter was significant (p≤0.05) with a negative effect and temperature for the microwave irradiation method. Additionally, the interaction between the abovementioned factors was significant for decomposition in the digester block. Thus, the decomposition conditions established by multivariate optimization were 180 ºC for 80 min and 140 ºC for 30 min, in a digester block and microwave, respectively, using 6 mL of 2 mol L-1 HNO3 and 2 mL of H2O2 30% (v v-1). The determined residual acidity was 0.76±0.0.04 mol L-1 with conductive heating and 0.40±0.03 mol L-1 by microwave irradiation. The proposed methods showed good precision (RSD <10%) with a wide working range, good linearity (R≥0.999), and detection and quantification limits below 0.18 and 0.61 mg L-1, respectively. The accuracy of both methods was confirmed by comparison with the reference method, with no occurrence of significant systematic errors (p>0.05). The developed decomposition procedures were applied to analyze white cheeses of the buffalo mozzarella, minas frescal, and ricotta types. The values found were compared with those indicated on each label, and each nutrient's contribution in its respective IDR was calculated.

COMMITTEE MEMBERS:
Presidente - 1190574 - RODOLFO DE MELO MAGALHAES SANTANA
Interno - 1698441 - RENNAN GEOVANNY OLIVEIRA ARAUJO
Interna - 282814 - MARIA DAS GRACAS ANDRADE KORN
Interna - 2721446 - DANIELE CRISTINA MUNIZ BATISTA DOS SANTOS
Externa à Instituição - KELLY DAS GRAÇAS FERNANDES DANTAS - UFPA
Externo à Instituição - ANIBAL DE FREITAS SANTOS JUNIOR - UNEB