Progress 10/01/04 to 09/30/09
Outputs
OUTPUTS: Study 1. Production of reduced fat Cheddar and process cheeses with improved characteristics using exopolysaccharides (EPS)-producing cultures: The objective of this work was to manufacture reduced fat Cheddar cheese with characteristics similar to those in the full fat counterpart. Proteolysis and textural, melting, viscoelastic, and sensory characteristics of reduced fat Cheddar cheeses made with different EPS-producing and nonproducing cultures were studied. EPS-producing cultures improved the textural, melting, and viscoelastic properties of reduced-fat Cheddar cheese. However, the EPS-positive cheese developed bitterness after 2 to 3 mo of ripening due to increased residual chymosin activity. We hypothesized that the reduced amount of chymosin needed to coagulate ultrafiltered milk might result in reduced Residual chymosin activity and bitterness in cheese. Exopolysaccharides-producing cultures were used in making reduced fat Cheddar cheese which was used as the base cheese in making reduced fat process cheese. Young Cheddar made with EPS-producing cultures would have a better functionality with smoother and less viscous texture than regular young cheeses. This research resulted in 7 presentations at scientific meetings and 8 publications in peer reviewed journals. Study 2. Production of Cheddar cheese containing high levels of CLA: The objective of this study was to determine the effects of diets on the level of CLA and textural characteristics of Cheddar cheese. The diets of 27 multiparous Holstein (18) and Brown Swiss (9) cows grazing alfalfa/grass pasture were supplemented with partial Total Mixed Rations (pTMR) containing 1) dried distillers grains (DDG), 2) soybean meal (SB), or 3) fishmeal (FM). Also, Cheddar cheese with enhanced levels of conjugated linoleic acid (CLA) was produced using two strains of lactic acid bacteria previously identified as high CLA producers. This research resulted in 4 presentations at scientific meetings. Study 3. Rheological properties of whey protein dispersions in the presence of exopolysaccharides: This research was based on the hypothesis that the interactions of EPS with proteins in the fermented medium determine its rheological characteristics (viscosity, ropiness). The aim of this research was to study the characteristics of EPS produced by Lactococcus lactis ssp. cremoris, and to better understand how those polysaccharides interact with proteins in milk under different conditions. This research resulted in 1 presentation at a scientific meeting a 2 publications in peer reviewed journals. Study 4. Rheological, sensorial, and chemopreventive properties of milk fermented with EPS-producing lactic cultures: Some polysaccharides produced by mushrooms and EPS produced by LAB have shown antitumor properties. The objective of this research was to evaluate the rheological, sensorial, and chemopreventive properties of milk fermented with different EPS-producing lactic cultures. This research resulted in 1 presentation at a scientific meeting and 1 publication in a peer reviewed journal. The principle investigator was invited to write a review article and gave 10 invited presentations worldwide. PARTICIPANTS: Individuals: Dr. Ashraf Hassan (PI). Planning and conducting research, data analysis and interpretation and manuscript and Thesis writing. Dr. Vikram Mistry (PI). Planning research, data interpretation and manuscript writing. Panna Agrawal (graduate student). Conducting research, data analysis, interpretation and presentation at scientific meetings and Thesis and manuscript writing. Ashish Pandit (graduate student). Conducting research, data analysis, interpretation and presentation at scientific meetings and Thesis and manuscript writing. Dr. Sanjeev Anand. Planning and conducting research, data analysis and interpretation and manuscript and Thesis writing. Dr. Ken Kalscheur (collaborator). Planning and conducting research, data analysis and interpretation and manuscript writing. Dr. Sameh Awad (postdoctoral associate). Conducting research, data analysis, interpretation and presentation at scientific meetings and manuscript writing. Ayala Hernandez (graduate student, University of Guelph). Conducting research, data analysis, interpretation and presentation at scientific meetings and Thesis and manuscript writing. Dr. Milena Corredig (collaborator, University of Guelph). Planning and conducting research, data analysis and interpretation and manuscript and Thesis writing. Rosemary Nyoka (graduate student). Conducting research, data analysis, interpretation and presentation at scientific meetings and Thesis and manuscript writing. Dr. Arnold Hippen (collaborator). Planning and conducting research, data analysis and interpretation and manuscript writing. Darshan Purohit ( graduate student). Conducting research, data analysis, interpretation and presentation at scientific meetings and Thesis and manuscript writing. Dr. E. Bhatia (postdoctoral associate). Conducting research, data analysis, interpretation and presentation at scientific meetings and manuscript writing. Dr. X. Zhang (postdoctoral associate). Conducting research, data analysis, interpretation and presentation at scientific meetings and manuscript writing. Dr. Chandradhar Dwivedi (collaborator). Planning and conducting research, data analysis and interpretation and manuscript writing. Dr. Jongwoo Choi (postdoctoral associate). Conducting research, data analysis, interpretation and presentation at scientific meetings and manuscript writing. Partner organizations: University of Guelph, Canada. This project provided training to 5 graduate students, 6 undergraduate students, and 4 postdoctoral associates. TARGET AUDIENCES: Dairy and food Industry. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Study 1: A 33% reduced-fat Cheddar cheese had similar textural characteristics as a full fat cheese if made with a ropy strain of Lactococcus lactis ssp. cremoris (JFR1). Furthermore, the changes in the texture of full-fat cheese and reduced-fat cheese made with the EPS-positive strain JFR1 followed the same pattern. Unlike reduced-fat cheese made with no EPS, hardness of both full-fat cheese and reduced-fat cheese made with the JFR1 culture increased during the first month of ripening. This would have a direct impact on reduced fat cheese used as an ingredient. Interestingly, both full-fat cheese and the EPS-positive cheese had a similar melting pattern. Panelists did not detect any differences in texture between full fat and reduced-fat cheeses. Ultrafiltration reduced residual chymosin activity which resulted in lower bitterness. Reduced fat process cheese made from EPS-positive Cheddar cheese had softer texture and better flow than did the control cheese. The study also provided important information on the relationship between the physical properties of the base cheese and those of the reduced fat process cheese. The modification in the characteristics of the base cheese does not always have a significant impact on reduced fat process cheese. No relationship was found between hardness and melting properties of the base reduced fat cheese and reduced fat process cheese, which indicates that factors affecting the physical and functional properties of those cheeses are not necessarily the same. Study 2: The CLA levels in cheese manufactured using a Lactococcus lactis strain increased from 0.86g/100g FA on day 1 to 0.97g/100g FA after 6 months of ripening. The study demonstrated the possibility of increasing levels of CLA in Cheddar cheese using lactic cultures without the need of substrate addition to milk. Feeding cows fish oil, which increased the level of CLA, did not affect textural properties or meltability of Cheddar cheeses. Study 3: The pH of fermentation and the addition of protein to the media had an effect on the molecular characteristics and functionality of the EPS produced by a Lactococcus lactis strain. The EPS molecules were negatively charged and interacted with whey proteins at low pH. The rheological behavior of the crude EPS in the fermented media was different from that in the purified form, confirming the importance of both molecular characteristics and interaction with proteins on the viscosifying effect. The results of this work suggest that the impact of EPS on the textural properties of fermented products is determined not only by their molecular parameters but also by the ability of the EPS to interact with milk proteins. Study 4: Fermented milks made with 2 EPS-producing strains and 1 non-producing culture showed chemopreventive effects in azoxymethane-induced tumors in rats. No relationship was found between the rheological and chemopreventive properties of fermented milk, and no conclusion could be drawn on the chemopreventive effect of EPS. Collaborations with University of Guelph, Canada, and College of pharmacy at South Dakota State University helped to achieve the project objectives.
Publications
- Abd El-aal, H., Dave, R., Khattab, Ali, and Hassan, A. N. 2009. Production of nisin-containing whey protein concentrate. Journal of Dairy Science 92 (E-Suppl 1): 26 (abstr.).
- Hassan, A. N., and Nigam, N. 2009. Relationship between base and process cheese characteristics. Journal of Dairy Science 92 (E-Suppl 1): 21 (abstr.).
- Hassan, A. N. 2008. Possibilities and challenges of exopolysaccharide-producing lactic cultures in dairy foods. American Dairy Science Association Foundation Scholar Award Lecture. Journal of Dairy Science. 91:1282-1298.
- Purohit, D. H., Hassan, A. N., Bhatia, E., and Dwivedi, C. 2009. Rheological, sensorial, and chemopreventive properties of milk fermented with exopolysaccharide producing lactic cultures. Journal of Dairy Science. 92:847-856.
- Awad, S., Hassan, A.N., and Mistry, V. V. 2009. Impact of exopolysaccharide-containing base Cheddar cheese on reduced fat process cheese. Milchwissenschaft. In Press.
- Purohit, D. H., Hassan, A. N., Bhatia, E., Dwivedi, C. 2008. Rheological and chemopreventive properties of milk fermented with exopolysaccharide-producing lactic culture. Journal of Dairy Science 91 (E-Suppl 1): 116 (abstr.).
- Pandit, A. J., Anand, S. K., Hassan, A. N., and Kalscheur, K. F. 2009. Lactic acid bacteria enhance levels of conjugated linoleic acid in Cheddar cheese. Journal of Dairy Science 92 (E-Suppl 1): 24-25 (abstr.).
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Study 1: Characteristics of reduced fat Cheddar cheese made from ultrafiltered milk with an exopolysaccharide (EPS)-producing culture. The objective of this research was to study the effect of 1.2x Ultrafiltration (UF) concentration on the textural and functional characteristics of reduced fat cheese. Ultrafiltration (1.2x) did not affect the hardness, cohesiveness, adhesiveness, chewiness, and gumminess of EPS-positive cheese. Texture of the EPS-negative cheese was more affected by UF than that of the EPS-positive cheese. Study 2: Production, isolation and characterization of exopolysaccharides produced by Lactococcus lactis subsp. cremoris JFR1 and their interaction with milk proteins. The aim of this research was to study exopolysaccharides (EPS) produced by Lactococcus lactis subsp. cremoris (JFR1), and their interactions with dairy proteins. The highest viscosities were obtained in media (ultrafiltration permeate) with added protein at pH 5.8 and 5.5. Isolated EPS showed a different rheological behavior from that of the whole fermented media. Fermentation at pH 5.5 produced molecules with higher molecular weight and a more compact structure than those produced at pH 6.5. EPS molecules are negatively charged and interact with whey proteins at acidic pH. Study 3: Production of conjugated linoleic acid in milk and cheese slurry by lactic acid bacteria. This study was undertaken to evaluate CLA production and their isomeric distribution in milk during fermentation by lactic acid bacteria (LAB). A total of 155 cultures of LAB, including 46 cultures from the Dairy Science Department′s culture collection, 68 isolates from retail cheeses, and 41 raw milk isolates were screened for CLA production. Cultures were individually inoculated in milk at 2% levels and incubated for 4 h at 37 C. Fat was extracted from milks at the end of incubation and the butyl esters were analyzed by gas chromatography. Control milks had an average CLA content of 0.41 gm/100 gm of fatty acids (FA). The highest level of CLA produced by lactic acid bacteria was 1.12 gm/100 gm FA. Lactic acid bacteria increased mainly the cis-9, trans-11 isomer and also produced 3 to 5 unidentified CLA isomers. On an average, cis-9, trans-11 represented 62.62%, and trans-10, cis-12 represented 17.77% of the total CLA. A cheese slurry method was used to screen CLA producing LAB for their suitability in cheese manufacturing with higher CLA levels. The CLA content of slurries before inoculation was 0.73 gm/100 gm fatty acids (FA). On day 1, CLA values of 0.94 were observed in some treatments. Maximum CLA content was 0.99 gm/100 gm FA after 3 d of incubation. None of the slurries were rancid after 5 d of incubation. PARTICIPANTS: Individuals: Dr. Ashraf Hassan (PI). Planning and conducting research, data analysis and interpretation and manuscript and Thesis writing. Dr. Vikram Mistry (PI). Planning research, data interpretation and manuscript writing. Panna Agrawal (graduate student). Conducting research, data analysis, interpretation and presentation at scientific meetings and Thesis and manuscript writing. Ashish Pandit (graduate student). Conducting research, data analysis, interpretation and presentation at scientific meetings and Thesis and manuscript writing. Dr. Sanjeev Anand. Planning and conducting research, data analysis and interpretation and manuscript and Thesis writing. Dr. Ken Kalscheur (collaborator). Planning and conducting research, data analysis and interpretation and manuscript writing. Partner Organizations: University of Guelph, Canada Collaborators and contacts: Ayala Hernandez (graduate student). Conducting research, data analysis, interpretation and presentation at scientific meetings and Thesis and manuscript writing. Dr. Milena Corredig (collaborator). Planning and conducting research, data analysis and interpretation and manuscript and Thesis writing. TARGET AUDIENCES: Dairy Industry, Food Industry PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Study 1: Higher body and texture scores were given to EPS-positive cheeses than the EPS-negative ones. Sensory panelists found the body of the UF and non-UF cheeses to be similar. Study 2: The impact of EPS on textural properties is determined not only by the molecular characteristics but also by the ability of EPS to interact with proteins. Study 3: Lactic acid bacteria can increase levels of CLA in fermented milk and possibly be used for making dairy products enriched with CLA. This study provides useful information on the feasibility of some CLA-producing starter culture in cheese manufacture. It was also useful in anticipating the behavior of different CLA producing cultures during cheese ripening.
Publications
- 1. Agrawal, P. and Hassan, A. N. 2008. Characteristics of reduced fat Cheddar cheese made from ultrafiltered milk with an exopolysaccharide-producing culture. Journal of Dairy Research. 75: 182-188.
- 2. Ayala-Hernandez, I., Hassan, A. H., Goff, H. D., Mira de Orduna, R, and Corredig, M. 2008. Production, isolation and characterization of exopolysaccharides produced by Lactococcus lactis subsp. cremoris JFR1 and their interaction with milk proteins: effect of pH and media composition. International Dairy Journal. 18:1109-118.
- 3. Ayala-Hernandez, I., Hassan, A. N., Goff, H. D., and Corredig, M. 2009. Effect of protein supplementation on the rheological characteristics of milk permeates fermented with EPS producing Lactococcus lactis subsp. cremoris. Food Hydrocolloids. In Press.
- 4. Pandit, A. J., Anand, S. K., Hassan, A. N., Kalscheur, K. F. 2008. Production of conjugated linoleic acid in cheese slurry by lactic acid bacteria. Journal of Dairy Science 91 (E-Suppl. 1):p118, July 8.
- 5. Pandit, A. J., Anand, S. K., Kalscheur, K. F., Hassan, A. N. 2008. Production of conjugated linoleic acid in milk by lactic acid bacteria. Journal of Dairy Science 91 (E-Suppl. 1):p109, July 8.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: Study-1. Effect of high fat supplements for grazing dairy cows on textural properties of Cheddar cheese. Previous studies showed that grazing on pasture and feeding diets supplemented with fish meal increased the level of conjugated linoleic acid (CLA) and its related isomers in cow's milk. The objective of this study was to determine the effects of such diets on the textural characteristics of Cheddar cheese. The diets of 27 multiparous Holstein (18) and Brown Swiss (9) cows grazing alfalfa/grass pasture were supplemented with partial Total Mixed Rations (pTMR) containing 1) dried distillers grains with solubles (DDG), 2) soybean meal (SB), or 3) fishmeal (FM). Milk was collected from morning milking and stored at 4 C for Cheddar cheese making the following day. Study-2. Rheological properties of whey protein dispersions in the presence of exopolysaccharides from Lactococcus lactis ssp. cremoris. Exopolysaccharides produced by some strains of lactic acid bacteria (LAB)
improve textural properties and increase water retention in fermented dairy products. In addition, the consumption of EPS has been associated to health benefits. Exopolysaccharides confer high viscosity and unique rheological properties to fermented milks, even at very small concentrations but the nature of the thickening properties has not yet been fully explained, since every strain produces different EPS and the molecular parameters seem to change depending on the fermentation conditions. This research was based on the hypothesis that the interactions of EPS with proteins in the fermented medium determine its rheological characteristics (viscosity, ropiness). The aim of this research was to study the characteristics of EPS produced by Lactococcus lactis ssp. cremoris, and to better understand how those polysaccharides interact with proteins in milk under different conditions. A highly ropy strain of Lactoccocus lactis ssp. cremoris (JFR1) was selected, and fermentations were
conducted in ultrafiltation (UF) permeate with and without added whey proteins at 30C under controlled pH and different fermentation times.
PARTICIPANTS: Individuals: Dr. Ashraf Hassan (PI). Planning and conducting research, data analysis and interpretation and manuscript and Thesis writing. Dr. Vikram Mistry (PI). Planning research, data interpretation and manuscript writing. Panna Agrawal (graduate student). Conducting research, data analysis, interpretation and presentation at scientific meetings and Thesis and manuscript writing. Dr. Sameh Awad (visiting Scientist). Conducting research, data analysis, interpretation and presentation at scientific meetings and manuscript writing. Partner Organizations: University of Guelph, Canada Collaborators and contacts: Ayala Hernandez (graduate student). Conducting research, data analysis, interpretation and presentation at scientific meetings and Thesis and manuscript writing. Dr. Milena Corredig (collaborator). Planning and conducting research, data analysis and interpretation and manuscript and Thesis writing. Rosemary Nyoka (graduate student). Conducting research, data
analysis, interpretation and presentation at scientific meetings and Thesis and manuscript writing. Dr. Arnold Hippen (collaborator). Planning and conducting research, data analysis and interpretation and manuscript writing. Dr. Ken Kalscheur (collaborator). Planning and conducting research, data analysis and interpretation and manuscript writing.
Impacts
Study-1. No significant differences in moisture, pH and fat on dry matter basis were observed among treatments. Free oil was higher (P<0.05) in the DDG (17.78%) and FM (17.59%) cheeses than in the control Soybean cheese (15.78%). Texture attributes (hardness, springiness, cohesiveness, gumminess and chewiness) decreased during the first mo of ripening. Whereas hardness, gumminess and cohesiveness continued to decrease between mo 1 and 3, an increase in chewiness and springiness was observed in all cheeses during this period. There were no significant differences among treatments in all cheese texture attributes. In conclusion, this study shows that diets that increase the level of CLA in milk did not affect cheese texture. Study- 2. The highest degree of ropiness and viscosity increase was obtained at pH values between 5.8 and 5.5 after 22 hrs of fermentation, and a significant loss of ropiness was observed after prolonged incubation. The increase of viscosity
correlated well with the level of ropiness. The molecular weights of the EPS obtained (determined by HPLC-MALS) were affected by the pH and the duration of the fermentation. Comparisons of fermentations performed with non-EPS producing strains on media with the same protein content helped to confirm the importance of the interaction of the polysaccharide with the protein to generate the viscosity increase. The results of this work suggest that the impact of EPS on the textural properties (ropiness and increased viscosity) of fermented products is determined not only by its molecular weight but also by its ability to interact with milk proteins.
Publications
- Agrawal, P., and A. N. Hassan. 2007. Ultrafiltered milk reduces bitterness in reduced fat Cheddar cheese made with an exopolysaccharide-producing culture. J. Dairy Sci. 90:3110-3117.
- Hassan, A.N., S. Awad, and V. V. Mistry. 2007. Reduced fat process cheese made from young reduced fat Cheddar cheese manufactured with exopolysaccharides-producing cultures. J. Dairy Sci. 90:3604-3612.
- Ayala Hernandez, I., A. N. Hassan, and M. Corredig. 2007. Rheological properties of whey protein dispersions in the presence of exopolysaccharides from Lactococcus lactis spp. cremoris. J. Dairy Sci. 90, (Suppl. 1) : 600. (Abstr.).
- Nyoka, R., A. R., Hippen, A. N. Hassan, and K. F. Kalscheur. 2007. Effect of high fat supplements for grazing dairy cows on textural properties of Cheddar cheese. J. Dairy Sci. 90, (Suppl. 1) : 272. (Abstr.).
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Progress 01/01/06 to 12/31/06
Outputs
Study 1: Young Cheddar cheese is characterized by excessive firmness, curdy and rubbery texture, poor meltability and lack of flavor. Exopolysaccharide (EPS)-producing cultures improve melting, viscoelastic and textural properties of young reduced fat Cheddar cheese. We hypothesized that the use of EPS-producing cultures in making base Cheddar cheese would allow the utilization of more young cheeses in making process cheese. Reduced fat process cheeses were manufactured using young (2-day) or 1-month old reduced fat Cheddar cheese made with EPS-producing or non-producing cultures. Moisture and fat of process cheese were standardized to 49 and 21%, respectively. Enzyme modified cheese (EMC) was incorporated to provide flavor of aged cheese. Exopolysaccharide-positive process cheese was softer, less chewy and gummy, and more deformable than the EPS-negative cheeses. Process cheese manufactured from EPS-containing Cheddar cheese exhibited lower viscoelastic moduli and
softening temperature. The hardness, chewiness and viscoelastic moduli were lower in process cheese made from 1-month old Cheddar cheese than those in process cheese made from 2-day old cheese. Larger differences were observed between process cheeses made from 1-month old EPS-positive and negative base cheeses than those between process cheeses made from the corresponding young (2 day old) base cheeses. This could be because of more extensive proteolysis in the EPS-positive Cheddar cheeses than in the EPS-negative cheeses due to their higher moisture content. Sensory scores for texture of EPS-positive process cheeses were higher than those of the EPS-negative ones. Study 2: Fat reduction in cheese is associated with many textural and functional defects. The quality attributes of process cheese are greatly influenced by the composition and nature of base cheeses. The objective of this study was to evaluate textural, viscoelastic and functional characteristics of reduced fat process
cheese made from EPS-containing Cheddar cheese. Reduced fat process cheeses were manufactured using a 50/50 mixture of young (2 days) and aged (6 months) reduced fat Cheddar cheeses made with EPS-producing or non-producing cultures. In addition, a full fat process cheese made with no EPS was also employed in this study. Moisture and fat were standardized to 40 and 32.5% for full fat cheese and 49 and 21% for reduced fat cheese respectively. Reduced fat process cheeses made from Cheddar cheese containing no EPS were firmer, and more chewy and gummy than those made from EPS-positive Cheddar cheese. Reduced fat process cheese manufactured from EPS-positive Cheddar cheese had lower viscoelastic moduli and increased meltability. Creep/recovery test showed that EPS-positive process cheese was more deformable and did not recover its original structure as much as the EPS-negative one did. Sensory results correlated well with instrumental data. The highest sensory scores were obtained when
both young and aged cheeses contained EPS. Full fat cheese was harder, chewier, gummier and less deformable than reduced fat cheeses, which might due to the lower moisture content in the former cheese.
Impacts
The use of exopolysaccharide (EPS)-producing cultures in making base Cheddar cheese would allow the utilization of more young cheeses in making process cheese. The texture of reduced fat process cheese may be improved by using EPS-positive base cheese.
Publications
- Awad, S., A. N. Hassan, and V. Mistry. 2006. Substituting aged cheese with exopolysaccharide-containing base cheese in making process cheese. J. Dairy Sci. 89, (Suppl. 1) : 314. (Abstr.).
- Awad, S., A. N. Hassan, and V. Mistry. 2006. Impact of exopolysaccharide-containing base cheese on characteristics of reduced fat process cheese. J. Dairy Sci. 89,(Suppl. 1) : 314. (Abstr.).
- Agrawal, P., and A. N. Hassan. 2006. Improving texture and flavor of reduced fat Cheddar cheese using an exopolysaccharide-producing culture and ultrafiltration. J. Dairy Sci. 89, (Suppl. 1) : 108. (Abstr.).
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Progress 01/01/05 to 12/31/05
Outputs
Proteolysis and textural, melting, viscoelastic and sensory characteristics of reduced fat Cheddar cheeses made with different EPS-producing and nonproducing cultures were studied. A ropy strain of Lactococcus lactis ssp. cremoris (JFR1) and capsule-forming nonropy and moderately ropy strains of Streptococcus thermophilus were used in making reduced-fat Cheddar cheese. Commercial Cheddar starter was used in making full-fat cheese. Results showed that the actual yield of cheese made with JFR1 was higher than that of all other reduced-fat cheeses. Cheese made with JFR1 contained higher moisture, moisture in the nonfat substance, and residual coagulant activity than all other reduced-fat cheeses. Proteolysis was also higher in cheese made with JFR1 than in all other cheeses. The HPLC analysis showed a significant increase in hydrophobic peptides (causing bitterness) during storage of cheese made with JFR1. Hardness, gumminess, springiness, and chewiness significantly
increased in the cheeses as fat content decreased. Cheese made with EPS-producing cultures was the least affected by fat reduction. No differences in hardness, springiness, and chewiness were found between young reduced fat cheese made with a ropy Lactococcus lactis ssp. cremoris JFR1 and its full-fat counterpart. Whereas hardness of full-fat cheese and reduced-fat cheese made with JFR1 increased during ripening, a significant decrease in its value was observed in all other cheeses. No differences in meltability were found between the young full-fat cheese and the reduced-fat cheese made with the ropy culture JFR1. No differences were detected by panelists between the textures of the full-fat cheese and reduced-fat cheese made with JFR1, both of which were less rubbery or firm, curdy, and crumbly than all other reduced-fat cheeses. No differences in the viscoelastic properties were found between young reduced-fat cheese made with a ropy strain of Lactococcus lactis ssp. cremoris
(JFR1) and its full-fat counterpart. Interestingly, the changes in viscoelastic moduli in both full-fat cheese and reduced-fat cheese made with JFR1 during ripening followed the same pattern. The creep and recovery properties of young reduced-fat cheese made with JFR1 and the full-fat type were similar. The cryo-scanning electron micrographs showed that young (1 week old) full fat cheese contained wide and long fat serum channels, which were formed because of fat coalescence. Such channels were not observed in the reduced-fat cheese. Young reduced-fat cheese made with EPS-nonproducing cultures contained fewer and larger pores than did reduced-fat cheese made with a ropy strain of Lactococcus lactis ssp. cremoris (JFR1), which had higher moisture levels. A 3-dimensional network of EPS was observed in large pores in cheese made with JFR1. Major changes in the size and distribution of pores within the structure of the protein network were observed in all reduced-fat cheeses, except that
made with JFR1, as they aged. Changes in porosity were less pronounced in both the full-fat and the reduced-fat cheeses made with JFR1.
Impacts
The texture of reduced fat Cheddar cheese may be improved by using exopolysaccharide (EPS)-producing cultures. This research suggests the appropriate type of EPS-producing cultures to be used in making reduced fat Cheddar cheese and recommend manufacturing conditions that would allow the production of this type of cheese with characteristics similar to those of its full fat counterpart.
Publications
- Awad, S., Hassan, A. and Halaweish, F. 2005. Application of exopolysaccharide-producing cultures in making reduced fat Cheddar cheese. Composition and proteolysis. J. Dairy Sci. 88 (Suppl 1):269 (abstr).
- Awad, S., Hassan, A. and Muthukumarappan, K. 2005. Application of exopolysaccharide-producing cultures in making reduced fat Cheddar cheese. Viscoelastic properties. J. Dairy Sci. 88 (Suppl 1):18 (abstr).
- Awad, S., Hassan, A. and Muthukumarappan, K. 2005. Application of exopolysaccharide-producing cultures in making reduced fat Cheddar cheese. Textural and melting properties. J. Dairy Sci. 88 (Suppl 1):17 (abstr).
- Hassan, A. and Awad, S. 2005. Application of exopolysaccharide-producing cultures in making reduced fat Cheddar cheese. Cryo-scanning electron microscopy observations. J. Dairy Sci. 88 (Suppl 1):17 (abstr).
- Awad, S., Hassan, A. N. and Muthukumarappan, K. 2005. Application of exopolysaccharide-producing cultures in making reduced fat Cheddar cheese. Texture and melting properties. J. Dairy Sci. 88: 4204- 4213.
- Hassan, A. N. and Awad, S. 2005. Application of exopolysaccharide-producing cultures in reduced fat Cheddar cheese. Cryo-scanning electron microscopy observations. J. Dairy Sci. 88: 4214- 4220.
- Awad, S., Hassan, A. N. and Halaweish, F. 2005. Application of exopolysaccharide-producing cultures in reduced fat Cheddar cheese. Composition and proteolysis. J. Dairy Sci. 88: 4195- 4203.
- Hassan, A. N., Awad, S. and Muthukumarappan, K. 2005. Effects of Exopolysaccharide-Producing Cultures on the Viscoelastic Properties of Reduced-Fat Cheddar Cheese . J. Dairy Sci. 88: 4221- 4227.
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