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The presented thesis deals with the monitoring sensory quality of processed cheese analogues, focusing mainly on the taste (flavour) and related content of volatile (aroma active) substances. Model samples of analogues were produced by a standard procedure at Tomas Bata University in Zlín. The experimental part was divided into two experiments, which differed in the composition of model samples of analogues. In the first experiment, the traditional fat (butter) was completely replaced by selected vegetable fats (palm, coconut, mixed), in the second experiment only a part (1% w/w - expressed on the total weight of the sample) of butter was replaced by vegetable oils (apricot, flax seed, currant, grape seed). Solid phase microextraction in conjunction with gas chromatography with flame ionization detection was used to determine volatiles. Methods based on valid international standards were used to evaluate the sensory quality of samples, focusing mainly on flavor, namely evaluation using scales (ISO 4121), profile test (EN ISO 13299) and ranking test (ISO 8587). The aim of the work was to assess the effect of the addition of various vegetable fats/oils on the above parameters, at the same time their changes were monitored during 6 months of storage (at 6 ° C). The results showed that the vegetable oil used affects both the sensory quality and the content and composition of volatile substances of analogues. Significant differences between samples were mainly in taste, aroma and overall acceptability. The decreasing overall acceptability of the samples can be expressed in experiment I by the order: product with butter coconut palm mixed fat; in the case of experiment II: product with butter apricot = flax = grape currant oil. Mixed fat, currant and grape seed oil proved to be unsuitable for the production of analogues, on the contrary, analogues with coconut fat and apricot oil were evaluated best. Based on the results of sensory analyses, it was shown that the samples maintain a good sensory quality min. for 3 months while maintaining a low storage temperature ( 6 ° C). An analogue with coconut fat, whose taste, aroma and acceptability were rated as very good, and apricot oil, whose taste, aroma and acceptability were even rated as excellent, could enrich the food offer on the market.

O objetivo desse estudo foi validar a aplicação da metodologia isotópica de identificação da origem dos gliceróis em gorduras presentes em requeijões e especialidades lácteas com o intuito de oferecer uma ferramenta de controle de qualidade, de fiscalização de mercado e detecção de fraudes. Para atingir esse objetivo, isolou-se o glicerol de compostos lácteos como requeijões, especialidades lácteas, leite e óleos vegetais (empregados como padrões de origem animal e vegetal, respectivamente) e aplicou-se a metodologia isotópica. O glicerol foi isolado através da centrifugação. Foram analisadas todas as marcas de requeijões e similares (28 marcas) disponíveis nos supermercados da cidade de Piracicaba, e depois, agrupadas conforme sua identificação: requeijão cremoso, especialidade láctea com requeijão cremoso, alimento à base de requeijão e creme vegetal, requeijão cremoso com amido e não identificado. Do total, cinco marcas apresentaram resultados com diferença significativa (p<0,05) quando comparados ao controle (padrão animal - leite). A metodologia isotópica permitiu identificar a origem do material analisado e detectar alterações nos padrões. Comprovou-se a eficácia da metodologia isotópica na identificação da origem da matéria graxa de requeijões e a aplicabilidade da técnica no controle de qualidade de lácteos, auxiliando tanto no recebimento de matéria-prima como de produto final. / The objective of this study was to validate the application of the isotopic methodology of identification of glycerol origin in the fat fraction of "requeijões" (Brazilian soft cheeses) and similar products aiming at the identification of a quality control instrument for market fiscalization and fraud detection. In order to pursue the specific objectives of this study, the glycerol was isolated from spreadable dairy products such as "requeijões" and others. Cow's milk and vegetable oils of known origins were adopted as standards. The isotopic methodology was applied to identify the origin of the carbon present in the glycerol molecule of the fats present in those foods. Glycerol was isolated according to a conventional based on centrifugation. Twenty-eight commercial brands of "requeijões" available in the supermarkets of Piracicaba city were classified according to the information provided in the lables and analyzed. Out of the total, 5 brands were significantly different (p<0,05) when compared to the control (animal pattern - milk), indicating absence of the milk fat in the formulation. The isotopic methodology allowed to identify the origin of the analyzed material and to detect alterations in the patterns. The effectiveness of the isotopic methodology in the identification of origin of the lipid constituents of "requeijão" was proven as well as the applicability of the technique in dairy industry quality control, both in the final product as well as in process supplies.

O objetivo desse estudo foi validar a aplicação da metodologia isotópica de identificação da origem dos gliceróis em gorduras presentes em requeijões e especialidades lácteas com o intuito de oferecer uma ferramenta de controle de qualidade, de fiscalização de mercado e detecção de fraudes. Para atingir esse objetivo, isolou-se o glicerol de compostos lácteos como requeijões, especialidades lácteas, leite e óleos vegetais (empregados como padrões de origem animal e vegetal, respectivamente) e aplicou-se a metodologia isotópica. O glicerol foi isolado através da centrifugação. Foram analisadas todas as marcas de requeijões e similares (28 marcas) disponíveis nos supermercados da cidade de Piracicaba, e depois, agrupadas conforme sua identificação: requeijão cremoso, especialidade láctea com requeijão cremoso, alimento à base de requeijão e creme vegetal, requeijão cremoso com amido e não identificado. Do total, cinco marcas apresentaram resultados com diferença significativa (p<0,05) quando comparados ao controle (padrão animal – leite). A metodologia isotópica permitiu identificar a origem do material analisado e detectar alterações nos padrões. Comprovou-se a eficácia da metodologia isotópica na identificação da origem da matéria graxa de requeijões e a aplicabilidade da técnica no controle de qualidade de lácteos, auxiliando tanto no recebimento de matéria-prima como de produto final. / The objective of this study was to validate the application of the isotopic methodology of identification of glycerol origin in the fat fraction of "requeijões" (Brazilian soft cheeses) and similar products aiming at the identification of a quality control instrument for market fiscalization and fraud detection. In order to pursue the specific objectives of this study, the glycerol was isolated from spreadable dairy products such as "requeijões" and others. Cow's milk and vegetable oils of known origins were adopted as standards. The isotopic methodology was applied to identify the origin of the carbon present in the glycerol molecule of the fats present in those foods. Glycerol was isolated according to a conventional based on centrifugation. Twenty-eight commercial brands of "requeijões" available in the supermarkets of Piracicaba city were classified according to the information provided in the lables and analyzed. Out of the total, 5 brands were significantly different (p<0,05) when compared to the control (animal pattern - milk), indicating absence of the milk fat in the formulation. The isotopic methodology allowed to identify the origin of the analyzed material and to detect alterations in the patterns. The effectiveness of the isotopic methodology in the identification of origin of the lipid constituents of "requeijão" was proven as well as the applicability of the technique in dairy industry quality control, both in the final product as well as in process supplies.