Progress 10/01/03 to 09/30/04
Outputs
Flavor and texture are important attributes that influence taste and consumption of dairy foods. Cheese flavors are a heterogeneous mixture of compounds originating from milk, activities of milk enzymes, and of the metabolism of the starter culture bacteria. For most ripened cheeses the identity and the critical combination of compounds involved in generating the typical flavor were not known. The long-term goals of this project were to develop acceptable quality hard goat cheese and to objectively establish a correlation method between the concentration of aromatic compounds and the state of maturity of regular and accelerated ripened hard goat cheese. The optimum processing conditions that resulted in production of acceptable quality cheese were determined and used. Gas chromatographic analyses of these cheeses were performed and the following volatile compounds that contribute to flavor of Jack cheese from goat milk were identified: propionaldehyde, butanal,
methanol, ethanol, pentanal, 2,3-butanedione, propanol, 2-hexanone, 3-ethyl-2-pentanone, butanol, 2-heptanone, pentanol, 3-methyl-2-pentanol, 3-hydroxy-2-butanone, hydroxy acetone, 2-nonanone, acetic acid, 2-decanone, 2,3-butanediol, butanoic acid, 2-methyl butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, and nonanoic acid. Proteolysis influences cheese texture and flavor. Softening of cheese texture during aging is enhanced by hydrolysis of caseins, primarily of alpha S1 casein. Specific degradation patterns of caseins and their effect on rheology of Monterey Jack-type goat cheese were studied during aging. The rheological properties of these cheeses were determined at day-1 and at 6-week intervals throughout the 30 week ripening period. Compression levels of 10, 20, and 75% were used for texture profile analyses. Hydrolysis of protein moieties of the experimental cheeses were evaluated by Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE)
at 6-week intervals during the ripening period. The destained electrophoresis gels were used to quantify degradative products of casein fractions by advanced computerized densitometric analysis of 1-D gels using NIH Image 1.6. The integrated area and intensity of each band was calculated which indicates the amount of proteolysis in different fractions of each cheese. We have also focused to shorten the ripening time of this hard goat cheese due to the economical implications of long aging process. This will be particularly helpful to the dairy industry in terms of saving time and reducing refrigeration costs. The effect of accelerated ripening of intracellular enzymes from starter culture on cheese texture and flavor was investigated in this project. The different levels of extracted intracellular enzymes added to each cheese treatment was assayed by aminopeptidase system. The effect of accelerated ripening during the aging period was studied by organoleptic technique.
Impacts
With the increased popularity and consumption of cheeses made from goat milk, efforts to develop new products and investigate the physical and chemical characteristics of these products have become economically more important and require utilization of research-based knowledge. Developing optimum processing techniques for production of a good quality goat milk Jack cheese and clarification of its physical and chemical characteristics are not only providing scientific information for further research but also furnish valuable information for practical application in production of this product.
Publications
- Attaie, Rahmat. March 29-April 2, 2003. Flavoring Compounds in High Moisture Goat Milk Jack Cheese. Thirteenth Biennial Research Symposium (Abstract).
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Progress 10/01/01 to 09/30/04
Outputs
Flavor and texture are important attributes that influence taste and consumption of dairy foods. Cheese flavors are a heterogeneous mixture of compounds originating from milk, activities of milk enzymes, and of the metabolism of the starter culture bacteria. For most ripened cheeses the identity and the critical combination of compounds involved in generating the typical flavor were not known. The long-term goals of this project were to develop acceptable quality hard goat cheese and to objectively establish a correlation method between the concentration of aromatic compounds and the state of maturity of regular and accelerated ripened hard goat cheese. The optimum processing conditions that resulted in production of acceptable quality cheese were determined and used. Gas chromatographic analyses of these cheeses were performed and the following volatile compounds that contribute to flavor of Jack cheese from goat milk were identified: propionaldehyde, butanal,
methanol, ethanol, pentanal, 2,3-butanedione, propanol, 2-hexanone, 3-ethyl-2-pentanone, butanol, 2-heptanone, pentanol, 3-methyl-2-pentanol, 3-hydroxy-2-butanone, hydroxy acetone, 2-nonanone, acetic acid, 2-decanone, 2,3-butanediol, butanoic acid, 2-methyl butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, and nonanoic acid. Proteolysis influences cheese texture and flavor. Softening of cheese texture during aging is enhanced by hydrolysis of caseins, primarily of alpha S1 casein. Specific degradation patterns of caseins and their effect on rheology of Jack cheese from goat milk were studied during aging. The rheological properties of these cheeses were determined at day-1 and at 6-week intervals throughout the 30 week ripening period. Compression levels of 20, and 75% were used for texture profile analyses. Hydrolysis of protein moieties of the experimental cheeses were evaluated by Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) at
6-week intervals during aging. The destained electrophoresis gels were used to quantify degradative products of casein fractions by advanced computerized densitometric analysis of 1-D gels using NIH Image 1.6. The integrated area and intensity of each band was calculated which indicated the amount of proteolysis in different fractions of each cheese. We have also focused to shorten the ripening time of this hard goat cheese due to the economical implications of long aging process. This will be particularly helpful to the dairy industry in terms of saving time and reducing refrigeration costs. The effect of accelerated ripening of intracellular enzymes from starter culture on cheese texture and flavor was investigated in this project. The different levels of extracted intracellular enzymes added to each treatment was assayed by aminopeptidase system. The effect of accelerated ripening during aging was studied by organoleptic technique.
Impacts
With the increased popularity and consumption of cheeses made from goat milk, efforts to develop new products and investigate the physical and chemical characteristics of these products have become economically more important and require utilization of research-based knowledge. Developing optimum processing techniques for production of a good quality goat milk Jack cheese and clarification of its physical and chemical characteristics are not only providing scientific information for further research but also furnish valuable information for practical application in production of this product.
Publications
- No publications reported this period
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Progress 10/01/01 to 09/30/02
Outputs
Flavor is an important attribute that influences the taste and consumption of dairy foods. Cheese flavors are a heterogeneous mixture of compounds originating from the milk, activities of milk enzymes, and of the metabolism of the starter culture bacteria. For most ripened cheeses the identity and the critical combination of compounds involved in generating the typical flavor are not known. The long-term goals of this project are to develop acceptable quality hard goat cheese and to objectively establish a correlation method between the concentration of aromatic compounds and the state of maturity of regular and accelerated ripened hard goat cheeses. The optimum processing conditions that resulted in production of acceptable quality cheese were determined and used. Gas chromatographic analyses of these cheeses were performed and the following volatile compounds that contribute to flavor of Monterey Jack goat cheese were identified: propionaldehyde, butanal, methanol,
ethanol, pentanal, 2,3-butanedione, propanol, 2-hexanone, 3-ethyl-2-pentanone, butanol, 2-heptanone, pentanol, 3-methyl-2-pentanol, 3-hydroxy-2-butanone, hydroxy acetone, 2-nonanone, acetic acid, 2-decanone, 2,3-butanediol, butanoic acid, 2-methyl butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, and nonanoic acid.
Impacts
Availability of applicable methodology that will enable goat milk processors to convert their milk into hard type cheeses will increase the diversity and quantity of our dairy foods. Manufacturing hard type goat milk cheeses and other dairy products will prevent spoilage of perishable goat milk that has a short shelf-life. Additionally, domestic production of hard type cheeses from goat milk will increase. This gives the dairy goat industry an opportunity to grow more and play a significant role in the agricultural sector of the economy, especially in areas where goat raising and dairying are more suitable and common.
Publications
- A part of the results of this project will be presented at the Association of Research Directors' Symposium in Atlanta, GA in March 30 to April 2, 2003. The title of the presentation is 'Determination of volatile compounds in Monterey Jack goat milk cheese.' This paper will be presented by: Rahmat Attaie, Cooperative Agricultural Research Center, Prairie View A&M University, Prairie View, Texas 77446
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