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Flavour Development (flavour + development)
Selected AbstractsFlavour formation by lactic acid bacteria and biochemical flavour profiling of cheese productsFEMS MICROBIOLOGY REVIEWS, Issue 3 2005Gerrit Smit Abstract Flavour development in dairy fermentations, most notably cheeses, results from a series of (bio)chemical processes in which the starter cultures provide the enzymes. Particularly the enzymatic degradation of proteins (caseins) leads to the formation of key-flavour components, which contribute to the sensory perception of dairy products. More specifically, caseins are degraded into peptides and amino acids and the latter are major precursors for volatile aroma compounds. In particular, the conversion of methionine, the aromatic and the branched-chain amino acids are crucial. A lot of research has focused on the degradation of caseins into peptides and free amino acids, and more recently, enzymes involved in the conversion of amino acids were identified. Most data are generated on Lactococcus lactis, which is the predominant organism in starter cultures used for cheese-making, but also Lactobacillus, Streptococcus, Propionibacterium and species used for surface ripening of cheeses are characterised in their flavour-forming capacity. In this paper, various enzymes and pathways involved in flavour formation will be highlighted and the impact of these findings for the development of industrial starter cultures will be discussed. [source] Effect of thermal treatment of incubated potato juice on the formation of Maillard volatilesINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 8 2003Stephen J. Davids Summary Potato juice samples, obtained from potatoes stored at different temperatures (0,24 °C) and times (8,20 weeks), were incubated (45,57 °C for 42 h) with or without commercial proteases. The samples were then used for thermal browning experiments by placing in either a heated oven at 125 °C overnight or in an autoclave at 132 or 121 °C for 1 h, these experiments promoted the occurrence of the Maillard reaction. After the heat treatment step, all samples were extracted with methylene chloride and analysed by gas chromatography/mass spectrometry. The data indicated that, by subjecting the potato juice to thermal treatments, a wide variety of volatiles generated by the Maillard were produced and these are known to be associated with specific flavour notes, examples are alkyl and acetyl pyrazines, piperazinediones, furans and pyrroles. These findings suggest that the study of potato juice extract as a new medium for flavour development, in particular in those applications which presently use malt, coffee, soybean, meat and yeast extracts, is a worthwhile endeavour. [source] A review on microwave baking of foodsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2001Gülüm Sumnu Summary Microwaves interact with polar molecules and charged particles of food to generate heat. There are differences between the heating mechanisms of microwave and conventional heating. The use of microwave heating has the advantage of saving energy and time, improving both nutritional quality and acceptability of some foods by consumers. Microwave ovens are successfully used both in homes and in the food service industry. However, there are still problems in perfecting microwave baking, therefore it is a popular research area. The main problems found to occur in microwave-baked food products are low volume, tough or firm texture, lack of browning and flavour development. Recent studies aim to improve the quality of microwave-baked products. This article reviews the basic principles of microwave baking, problems commonly occurring in microwave-baked products and finally studies published concerning microwave-baked products. [source] Glutamate dehydrogenase activity in lactobacilli and the use of glutamate dehydrogenase-producing adjunct Lactobacillus spp. cultures in the manufacture of cheddar cheeseJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2006A.G. Williams Abstract Aims:, The study was undertaken to investigate the occurrence of glutamate dehydrogenase activity in different species of lactobacilli, and to determine, in a series of cheese-making trials, the effects of glutamate dehydrogenase-producing adjunct cultures on sensory attribute development during the maturation of cheddar cheese. Methods and Results:, The presence of dehydrogenase activity with glutamate as substrate was monitored in cell lysates of >100 strains from 30 different species of lactobacilli using a qualitative colorimetric plate screening assay. Activity was detectable in 25 of the 29 representative species obtained from culture collections and in 12 of the 13 non-starter species isolated from cheese. There were pronounced interspecies and strain differences in the occurrence, level and pyridine nucleotide specificity of the glutamate dehydrogenase activity detected. Among the non-starter lactobacilli the highest frequency of enzyme occurrence and activity was detected in the Lactobacillus plantarum isolates. The establishment of glutamate dehydrogenase-producing adjunct strains in the predominant population of lactobacilli in the cheese curd affected the formation of a number of volatile compounds in ripening cheddar cheese, while the presence of Lact. plantarum strains, in particular, was associated with an intensification and acceleration of aroma and flavour development during the maturation period. Conclusions:, Glutamate dehydrogenase formation by lactobacilli is a strain-dependent metabolic attribute, and adjunct cultures expressing the activity that are able to proliferate during cheese ripening have a positive impact on the rate of development and the intensity of cheddar cheese aroma and flavour development. Significance and Impact of the Study:, It has been demonstrated that some strains of glutamate dehydrogenase-producing lactobacilli have potential use as adjunct cultures to accelerate and intensify aroma and flavour formation during the manufacture of cheddar and, by analogy, other similar varieties of cheese. The importance of phenotypic discriminative monitoring of the dominant lactobacilli present during ripening to confirm adjunct establishment and population complexity was highlighted as was the requirement to establish the metabolic attributes of the non-starter population in uninoculated control cheeses in comparative trials. [source] Effect of the fungal protease EPg222 on proteolysis and texture in the dry fermented sausage ,salchichón'JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2005María J Benito Abstract Proteolytic activity of the fungal protease EPg222 and its effect on the texture of the dry fermented sausage ,salchichón', which has a long ripening process, was assayed. Samples with enzyme added showed a significant reduction of myofibrillar protein concentration during the ripening period, compared with a control, and proteolytic activity of the enzyme led to a higher accumulation of non-protein and -amino acid nitrogen. Analysis of volatile compounds in ripened dry fermented sausages revealed that only in EPg222 batches were branched compounds derived from amino acids catabolism detected that are associated with the flavour of dry cured meat products. The texture profile analysis showed reduction in hardness, gumminess and chewiness values in treated compared with control sausages. The effect of this enzyme could be of great interest in stimulating proteolysis, in flavour development and in reducing the hardness of dry fermented sausages produced by a long ripening process. Copyright © 2004 Society of Chemical Industry [source] l -leucine aminopeptidase production by filamentous Aspergillus fungiLETTERS IN APPLIED MICROBIOLOGY, Issue 6 2005K.M. Nampoothiri Abstract Aims:, To screen various filamentous fungi belonging to Aspergillus spp. producing leucine and methionine aminopeptidases. Methods and Results:, Twenty-eight Aspergillus strains representing 14 species within the genus were screened for l -leucine aminopeptidase (LAP) production in two media in shake flask fermentation. Two Aspergillus sojae (NRRL 1988 and NRRL 6271) and one Aspergillus oryzae (NRRL 6270) strains were selected as the best producers for further studies. The peak LAP activities were 2·61, 2·59 and 1·30 IU ml,1 for the three fungi on days 2, 5 and 4 respectively. In addition to LAP, l -methionine aminopeptidase (MAP) activity was also detected. Apart from submerged fermentation, the highest LAP yields by solid-state fermentation were 11·39, 17·40 and 13·02 IU g,1 dry matter for the above fungi. The temperature and pH optimum of the enzyme was found to be in the range of 65,75°C at pH 8·0,9·0 for all three fungi. Metal ions, Co2+ and Fe2+ in 2 mmol l,1 concentration apparently enhanced the relative enzyme activity and heat stability. Conclusions:, Two A. sojae (NRRL 1988 and NRRL 6271) and one A. oryzae (NRRL 6270) strains were found to be the best producers of LAP and MAP. The preliminary characterization studies revealed that the enzyme is considerably thermostable and belongs to the class metalloenzymes. Significance and Impact of the Study:, A good number of aspergilli were screened and the ability of the fungal aminopeptidase to release a particular N-terminal amino acid along with its high thermal stability, makes them interesting for controlling the degree of hydrolysis and flavour development for a wide range of substrate. [source] Plant management research: status and what it can offer to address challenges and limitationsAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 2010P.R. CLINGELEFFER Abstract Seasonal fluctuations in yield, grape composition and wine attributes, largely driven by variable climatic conditions, are major challenges for the wine industry aiming to meet consumer expectations for consistent supply, wine style and product quality. This paper will address known causes for this variability and identify management techniques, together with their limitations, that offer potential to modulate these responses. Results will be presented from research studies, conducted over a number of seasons, which link vineyard management practices with fruit composition and wine assessments. They show that there is potential to develop integrated systems to stabilise yield, fruit composition and wine quality attributes across seasons. These techniques include lighter pruning, deficit irrigation techniques and adoption of low-moderate vigour rootstocks which lead to reduced shoot vigour and the development of open canopies and small bunches with small berries, with enhanced colour, phenolics and sensory appeal; application of mechanical and chemical crop thinning techniques for yield stabilisation and promotion of early ripeness, colour and flavour development. However, the results also show that variability between seasons in many cases is much larger than can be achieved by modifying management practices. Hence, opportunities to use management practices to completely reduce the seasonal variability, particularly with respect to grape composition and wine attributes, factors largely affected by climatic conditions during berry development, may be limited. There exists significant potential in the longer term to use new varieties and rootstocks better adapted to variable and changing climatic conditions. It can be concluded that vineyard practices can be modified to stabilise yield, grape composition and wine attributes to varying degrees and hence, minimise the impact of variability in climatic conditions from season to season. In the longer term, the adoption of new varieties together with new rootstocks adapted to higher temperatures and limited water supply will assist the wine industry to cope with impacts of climate variability and change and address ever changing consumer expectations. A total systems approach to vineyard management offers potential to modulate seasonal fluctuations in yield, grape composition and wine quality attributes with significant benefit for an industry. [source] | |||||||||||||