In an attempt to determine the most important free amino acids (FAAs) in the development of the flavour of beef broths, the amino acid compositions of beef broths prepared at different temperatures and cooking times, with flavours of different intensities, were studied. From our data, broths obtained at temperatures above 75 7C and cooking times longer than 120 min had significantly lower levels of most of the FAAs studied (P~0.05). Statistical analysis of the sensorial and analytical data (principal component analysis, chi-square analysis) permitted the different FAAs to be grouped in relation to the flavour. There was a significant association between elevated levels of glutamic acid, asparagine (P~0.01), lysine and methionine (P~0.05) and the development of beef broth flavour. However, this was inversely related to levels of cysteine, proline, serine, M-histadine, tyrosine, valine, arginine and aspartic acid whereas reduced levels of balanine, asparagine, tyrosine, threonine, methionine, cysteine, leucine, isoleucine, tryptophan, glutamic acid, histidine, lysine and phenylalanine were associated with sapid properties not characteristic of beef broths (astringent, warmed-over flavours). A significant correlation (P~0.01) between sensory evaluation and carnosine and anserine levels was also observed.

The components of broths obtained at different cooking temperatures (from 55 °C to boiling under reflux) have been related, through regression analysis, with their sensorial evaluation. An increase in cooking temperature led to a significant rise (P ≤ 0.05) in the concentration of nitrogen in peptides of molecular weight higher than 600 Da (HPPN, higher than 600 Da peptidic nitrogen), nitrogen in non‐amino acid substances of less than 600 Da (SNAN, small non‐amino acid nitrogen compounds), creatinine, inosine 5′‐monophosphate (IMP) and adenosine 5′‐monophosphate (AMP) in beef broths. The levels of SNAN, IMP, AMP, guanosine 5′‐monophosphate (GMP) and creatine showed a positive and significant relation (P ≤ 0.01) with the sensorial evaluation. Simple linear regression analysis showed that the beef broth flavour is inversely related to the protein nitrogen (PN) concentration. Multiple linear regression analysis suggested that flavour properties of beef broths were more influenced by the IMP concentration than the GMP and AMP concentration and that SNAN is more important than HPPN. Significant correlations (P ≤ 0.01) established between D‐ribose content, sensorial evaluation and amino acid nitrogen (AN) concentration suggested that besides amino acids and free sugars, substances from the earlier steps of Maillard reactions are involved in the obtention of suitable beef broth flavour at 85 °C. Nevertheless, the development of off‐flavours at cooking temperatures higher than 95 °C, especially warmed‐over flavour (WOF), suggests that it is advisable to restrict the reactions that occur at high temperatures. © 2000 Society of Chemical Industry

No abstract

Of the range of preparation conditions studied here, the beef broths with the most favourable sensory characteristics (P ≤ 0.05) were those manufactured with minced meat in a 7.5 g l−1 NaCl solution in proportions of 1:2 (w/v), heated at 85 °C for 60 min (the beef broth flavour was clean, clear, without any off‐flavour). Our data indicate the importance of accurately determining the heat treatment, since intermediate treatments yielded beef broths of good quality, whereas less intense treatments produced broths with raw meat and bloody and metallic flavours, and intensely heated broths had a warmed‐over or sour and astringent flavour. At higher temperatures the cooking time required to obtain a good‐quality broth decreased. From the analysis of variance of the sensorial data, temperature plays a more important role than cooking time in the development of the sensory properties of beef broths. © 2000 Society of Chemical Industry

Of the range of preparation conditions studied here, the beef broths with the most favourable sensory characteristics (P 0.05) were those manufactured with minced meat in a 7.5 g l À1 NaCl solution in proportions of 1:2 (w/v), heated at 85°C for 60 min (the beef broth¯avour was clean, clear, without any off-¯avour). Our data indicate the importance of accurately determining the heat treatment, since intermediate treatments yielded beef broths of good quality, whereas less intense treatments produced broths with raw meat and bloody and metallic¯avours, and intensely heated broths had a warmed-over or sour and astringent¯avour. At higher temperatures the cooking time required to obtain a good-quality broth decreased. From the analysis of variance of the sensorial data, temperature plays a more important role than cooking time in the development of the sensory properties of beef broths.