Maria Patrícia Milagres

Development and validation of the high performance liquid chromatography-ion exclusion method for detection of lactic acid in milk

The present work reports the development and validation of an analytical method for lactic acid quantification in milk by ion exclusion-HPLC with UV detection. This method showed good precision (variation coefficient <7.0%) and good accuracy (97.6-99.6%). Calibration curves were linear (R(2)>0.996) at the tested range of 5.0-25.0mmolL(-1); and the detection and quantification limits were 0.5 and 1.0mmolL(-1), respectively. Analysis of lactic acid in fermented milk (FM) or NaOH neutralised fermented milk (FNM) was performed using samples obtained during 9h of fermentation. An ANOVA analysis combined with the Tukey test was used to show that the method was insensitive to the differences between FM and FNM. The proposed method therefore proved to be a useful quality control tool in laboratories because it was able to determine milk acidity even in adulterated samples.

Night milking adds value to cow's milk.

BACKGROUND Melatonin is synthesized in greater concentration at night, and it plays an important role in sleep regulation. This study aimed to evaluate the melatonin concentration in milk collected by milking during the night and evaluates its effect, with or without tryptophan supplementation, in the sleep quality of adult Wistar rats. RESULTS A difference (P < 0.05) was observed between the milking times, where the milk obtained at 02:00 presented a higher melatonin concentration (39.43 pg mL(-1) ) than that acquired at 15:00 (4.03 pg mL(-1) ). A biological assay was also performed on 32 male adult Wistar rats distributed among four groups (n = 8): those receiving an AIN-93M diet (control group) and three test groups [diets containing milk from milking at 02:00 (M2h ), milking at 15:00 (M15h ), and milking at 02:00 plus tryptophan supplementation (M2h T)] for 28 days. It was observed that the control group did not differ (P > 0.05) from the M15h group in terms of the levels of blood melatonin and urinary sulfatoxymelatonin, but differed from groups M2h and M2h T, whereas group M2h T presented higher blood melatonin and urinary sulfatoxymelatonin concentrations. CONCLUSION Combining the techniques of night milking with tryptophan supplementation resulted in production of milk that improves sleep quality in rats.

Análise físico-química e sensorial de doce de leite produzido sem adição de sacarose

O objetivo foi avaliar doces de leite produzidos sem adicao de acucar. Realizaram-se tres formulacoes: doce com adicao de acucar (A), com edulcorante sucralose (B) e doce com ciclamato, sacarina e sorbitol (C). Nos doces B e C utilizou-se a carragena. Realizaram-se analises fisico-quimicas, microbiologicas, exigidas pela legislacao vigente, e analise sensorial. Nas analises de acidez nao houve diferenca significativa entre as amostras. O teor de gordura, a atividade de agua e textura das amostras nao diferiram entre os doces B e C, e esses diferiram estatisticamente do A. Nas analises de pH houve diferenca significativa entre os doces. O teor de solidos soluveis do doce A apresentou 63 °Brix, e os doces B e C, 26 °Brix. Na aceitacao, observou-se diferenca significativa para todos os atributos avaliados. Para sabor, o doce A foi mais aceito que os doces B e C, e o doce B mais que o C. Para atributo de textura sensorial e impressao global, o doce A foi mais aceito que os doces B e C, e esses apresentaram a mesma aceitacao. Na analise de textura instrumental, os doces B e C nao obtiveram a mesma forca de resistencia a penetracao que o doce A. Todas as analises microbiologicas dos doces A, B e C apresentaram-se dentro dos padroes exigidos pela legislacao vigente. Doce de leite com sucralose (B) mostrou-se uma boa alternativa para substituicao do doce de leite com sacarose (A), uma vez que obteve boa aceitacao para o atributo sabor.

ANÁLISE DE RISCO NA AVALIAÇÃO DA INFLUÊNCIA DA MARCA NA ACEITABILIDADE NÃO SENSORIAL DE REQUEIJÃO CREMOSO

Consumer behavior is influenced by intrinsic (sensory characteristics) and extrinsic (non-sensory characteristics) of the product. Among the non-sensory factors, highlights been studied by various areas of knowledge and strength channeled through companies in order to entice the consumer at the time of purchase. In recent decades, many statistical methods have been employed in order to study this important influence on consumer behavior, both in marketing as in sensory analysis. This study aimed to evaluate the impact of brand on the acceptance of cheese using the statistical technique of relative risk. Thus, the sensory test was conducted in two sessions, with the first, the samples were presented coded (test without information) and the second presented with their respective brands. Comparing the results obtained for the two sessions, it was found that there was no change in acceptance of the cheesecurd for all brands and technical statistical analysis showed the relative risk of easy application, interpretation and effective in studies of non-sensory characteristics of food.