How does roasting process influence the retention of coffee aroma compounds by lyophilized coffee extract?

The aims of this study were (1) to study the effect of lyophilized coffee extract on the retention of aroma compounds and (2) to study if aroma compounds selected are differently affected by the lyophilized coffee extracts obtained from conventional and Torrefacto coffee brews prepared by filter coffeemaker and by espresso coffee machine. Variable amounts of lyophilized coffee extracts, relative to coffee powder, containing different percentages of high molecular weight compounds, mainly melanoidins (value given in parentheses), were obtained: 20.9% (14.8) and 24.9% (23.3), respectively, for conventional and Torrefacto coffee brew prepared by filter coffeemaker and 18.1% (18.8) and 20.7% (57.5), respectively, for conventional and Torrefacto coffee brew prepared by espresso coffee machine. The retention of aroma compounds increased by increasing the lyophilized coffee extract concentration and was found to be dependent on the aroma compounds. The retention of aroma compounds was found to be slightly different depending on the brewing procedure employed, showing lyophilized coffee extracts obtained with espresso coffee machine had higher retention values that those extracted by filter coffeemaker. Retention capacity of lyophilized coffee extracts obtained from the conventional and the Torrefacto roasted coffee did not show differences except in the case of ethyl nonanoate.

Influence of water pressure on the final quality of arabica espresso coffee. Application of multivariate analysis.

Water pressure is one of the most important factors which influence the final quality of espresso coffee (EC). However, few studies dealing with this issue have been found. The aim of this work was to study the effect of water pressure on the final quality of Arabica ECs as well as to classify ECs prepared at different pressures (7, 9, and 11 atm) according to their physicochemical and sensory characteristics, key odorants, by means of multivariate analysis. Statistically, principal component 1 (PC1) separated ECs prepared at 7 and 9 atm from ECs prepared at 11 atm and included the main foam and taste characteristics as well as some key odorants and flavor compounds. ECs prepared at 7 and 9 atm were separated by principal component 2 (PC2). Coffees prepared at 9 atm showed consistency of foam and a high percentage of key odorants related to freshness and fruity, malty, and buttery flavors. A simple discriminate function was obtained by discriminate analysis, allowing the classification of ECs prepared at three pressures into their respective groups with a success rate of 100%.

Characterization of espresso coffee aroma by static headspace GC-MS and sensory flavor profile.

The aromas of three espresso coffee (EC) samples from different botanical varieties and types of roast (Arabica coffee, Robusta natural blend, and Robusta Torrefacto blend (special roast by adding sugar)) were studied by static headspace GC-MS and sensory flavor profile analysis. Seventy-seven compounds were identified in all of the EC samples. Among them, 13 key odorants have been quantified and correlated with their flavor notes by applying multivariate statistical methods. Some correlations have been found in the EC samples: some aldehydes with fruity flavors, diones with buttery flavors, and pyrazines with earthy/musty, roasty/burnt, and woody/papery flavors. By applying principal component analysis (PCA), Arabica and Robusta samples were separated successfully by principal component 1 (60.7% of variance), and Torrefacto and Natural Robusta EC samples were separated by principal component 2 (28.1% of total variance). With PCA, the aroma characterization of each EC sample could be observed. A very simple discriminant function using some key odorants was obtained by discriminant analysis, allowing the classification of each EC sample into its respective group with a success rate of 100%.

A method for identification of frozen meat used for production of cooked ham.

A simple method to distinguish if the meat used for production of cooked hams was frozen or unfrozen was developed. Several analytical parameters of quality in meat products (general and colour parameters and protein fraction) were determined in two types of cooked hams: one elaborated with refrigerated (R) and another with frozen and thawed (F/T) raw hams. Student's t-test was applied to compare both groups, but it could not be concluded if R and F/T cooked hams had the same quality or not. For this reason two multivariate statistical analyses, Factor (FA) and Discriminant Analysis (DA), were applied. The application of FA resulted in the separation of the two groups of cooked hams and allowed the selection of the parameters which were used in Discriminant Analysis (DA). A discriminant function, that is both easy to use and to interpret, was obtained.

Use of lipase from Rhizomucor miehei in dry fermented sausages elaboration: Microbial, chemical and sensory analysis.

Three different amounts of lipase (0.075, 0.100 and 0.150 LU/g) from Rhizomucor miehei (Palatase M 200L Novo Nordisk) were used to determine the correct amount to use in dry fermented sausages. Determination of acidity values through fourteen days of ripening showed that 0.100 LU/g was the most appropriate. Two types of fermented sausages were manufactured, addition of the enzyme being the only difference between them. Addition of Palatase did not affect product stability (pH and A(w)), and the growth of micro-organisms. In spite of the increase in acidity value, no rancidity developed as determined by both chemical and sensory analysis. Increases in the liberation of palmitic, palmitoleic, stearic, oleic and linoleic acids were found when lipase was used. Juiciness and taste were slightly better in the sausages with Palatase than in those without, but these differences were not reflected in the overall acceptability.

Colour evaluation of chorizo de Pamplona, a Spanish dry fermented sausage: Comparison between the CIE L(∗)a(∗)b(∗) and the Hunter lab systems with illuminants D65 and C.

Objective colour evaluation was determined for 33 samples of "chorizo de Pamplona" using the CIE L(∗)a(∗)b(∗) and the Hunter system with two illuminants (D65 and C). Highly significant differences between the measures obtained with the two illuminants were found for the three colour co-ordinates (L(∗)a(∗)b(∗) and Lab) in both systems. The highest coefficient of variation in b was with the Hunter system and in a was with the CIE L(∗)a(∗)b(∗) system, suggesting that the CIE system is better for separating samples according to yellowness, while the Hunter system is better for separating samples according to redness. Correlations with sensory evaluation were similar for both systems and illuminants, the lowest values being for yellowness.