Banca de DEFESA: MARLY SILVEIRA SANTOS
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.DISCENTE : MARLY SILVEIRA SANTOS
DATA : 09/12/2019
HORA: 09:00
LOCAL: Auditório Escola de Nutrição
TÍTULO:
Use of Red Propolis as a Food Additive for Yogurt Conservation
PALAVRAS-CHAVES:
Antioxidant. Conservation. Yogurt. Red propolis.
PÁGINAS: 144
GRANDE ÁREA: Ciências Agrárias
ÁREA: Ciência e Tecnologia de Alimentos
SUBÁREA: Ciência de Alimentos
ESPECIALIDADE: Química, Física, Fisico-Química e Bioquímica dos Alim. e das Mat-Primas Alimentares
RESUMO:
Yogurt derives from the fermentation of pasteurized or sterilized milk, using protosymbiotic cultures of Streptococcus salivarius subsp. thermophilus and Lactobacillus delbrueckii subsp. bulgaricus with addition or not of other lactic acid bacteria, which determine the characteristic of the product. Chemical additives are used to increase yogurt shelf life and some of them may be harmful to health. Consumers have been more demanding for natural foods without chemical preservatives. In this context, propolis is an attractive ingredient to produce natural and healthy foods, due to its antimicrobial, anti-inflammatory, healing and anesthetic properties, as well as the immunomodulatory effect, among others. This study aimed to evaluate the addition of red propolis on conservation of the stirred yogurt (YRP), strawberry flavor, replacing the potassium sorbate commonly used in conventional yogurt (CY). The yogurts obtained were submitted to stability tests under refrigeration through the determination of bio-indicators, such as Salmonella spp., coliforms at 37°C and Escherichia coli, molds and yeasts, as well as lactic acid bacteria. In addition, were evaluated the physical-chemical properties, presence of bioactive compounds, antioxidant activity, and fatty acids profile. The physical-chemical properties were evaluated using traditional methods, antioxidant activity by FRAP and DPPH methods and the presence of bioactive compounds through the content on phenols and flavonoids. In the second part of the study, YRP samples were evaluated for rheologic properties, sensory analysis and purchase intent. The sensory analysis and purchase intent of YRP and commercial yogurt (obtained at retail), strawberry flavor, was conducted with 90 untrained consumers. The results of the physical-chemical properties, fatty acids, texture and sensory analysis, and purchase intent were submitted to statistical treatments, and the means were compared the Tukey test. The results for microbiological stability showed that yogurt incorporated with red propolis (0.046%) (YRP) and conventional yogurt (CY) samples have shelf life of 28 days, which is desirable for product marketing. However, there was a decrease in lactic acid bacteria count in CY, which does not comply with the Brazilian legislation. The values for pH of YRP and CY samples ranged from 4.35 to 4.03 and 4.30 to 4.00 (0 to 28 days), and titratable acidity 1.28 to 0.85 and 1.27 to 0.83 (0 to 28 days), respectively. Related to protein content, the YRP presented a mean value of 3.16 and CY of 3.20, ashes YRP 0.70 and CY 0.71, moisture, YRP 87.44% and CY 87.56%, lipids, YRP 3.28% and CY 3.10%, and carbohydrates, YRP 23.56% and CY 22.70%. There were no significant differences in the physical-chemical properties of samples when compared to control. The main fatty acids detected in YRP and CY samples were palmitic, oleic + elaidic, myristic and stearic acids, with a statistically significant difference in the content of caprylic acid. In the samples of YRP, the DPPH value ranged from 0.93 to 1.09 Trolox/g at time zero and from 0.66 to 0.85/g Trolox/g at 28 days. FRAP values ranged from 12.10 to 13.81 mg Fe (II)/g at time zero and from 8.33 to 10.93 mg Fe (II)/g at 28 days. The values of phenols were between 5.49 and 5.73 mg eq. AG/g at time zero and from 5.38 to 3.65 mg eq. AG/g at 28 days. Flavonoids ranged from 0.11 to 0.28 mg AG/g at time zero and from 0.09 to 0.21 mg eq. AG/g at 28 days. These results showed the antioxidant activity and the presence of bioactive compounds in propolis. The average value found for apparent viscosity in YRP was 307.27 mPa, demonstrating a pseudo-plastic fluid not Newtonian behavior, as expected for stirred yogurt. Texture properties, such as cohesiveness, firmness, adhesion, elasticity and gum were similar to those of commercial yogurt. The sensory evaluation of the YRP samples presented an average score equal of 9.0, similar to that achieved in the evaluation of commercial yogurt, on a scale of 10 points, which means “liked a lot”. Regarding purchase intent, YRP samples showed a score of 64.45% of positive intention, while the commercial yogurt sample had 96,67%. According to the results can be concluded that the crude extract of red propolis is an excellent additive for conservation of natural yogurt and can replace chemical additives commonly used in the product, without changing viability of lactic acid bacteria.
MEMBROS DA BANCA:
Presidente - 281042 - ROGERIA COMASTRI DE CASTRO ALMEIDA
Interno - 414993 - GILSON TELES BOAVENTURA
Externo ao Programa - 1475020 - MARIA EUGENIA DE OLIVEIRA MAMEDE
Externo ao Programa - 1980101 - MARCELO ANDRES UMSZA GUEZ
Externo à Instituição - NORMA SUELY EVANGELISTA BARRETO - UFRB