Proteolysis is one of the most important biochemical reactions during cheese ripening.Studies on the secondary structure of proteins during ripening would be helpful for characterizing protein changes for assessing ch...Proteolysis is one of the most important biochemical reactions during cheese ripening.Studies on the secondary structure of proteins during ripening would be helpful for characterizing protein changes for assessing cheese quality.Fourier transform infrared spectroscopy(FTIR),with self-deconvolution,second derivative analysis and band curve-fitting,was used to characterize the secondary structure of proteins in Cheddar cheese during ripening.The spectra of the amide I region showed great similarity,while the relative contents of the secondary structures underwent a series of changes.As ripening progressed,the α-helix content decreased and the β-sheet content increased.This structural shift was attributed to the strengthening of hydrogen bonds that resulted from hydrolysis of caseins.In summary,FTIR could provide the basis for rapid characterization of cheese that is undergoing ripening.展开更多
Low fat cheeses often suffer from undesirable texture and flavor. The objective of this study is to improve the yield, texture, flavor and quality of low fat Cheddar cheese during ripening using exopolysaccharide-prod...Low fat cheeses often suffer from undesirable texture and flavor. The objective of this study is to improve the yield, texture, flavor and quality of low fat Cheddar cheese during ripening using exopolysaccharide-producing lactobacilli and ripening cultures. The article represents one of the first attempts to tackle both texture and flavor at the same time. The study reveals the effect of aging on the texture and flavor of low fat Cheddar cheese over a ripening period of six months. The cheese manufactured with a modified protocol using EPS-producing cultures and ripening cultures showed higher values for moisture content (45%) and yield (9.4%) when compared to cheese manufactured with the conventional procedure and without the addition of EPS-producing cultures and ripening cultures (37.7%) and (4.9%) respectively. The obtained results indicated a 70% decrease in the fat content of the cheese. Texture profile analysis (TPA) indicated that the hardness, the cohesiveness, the springiness, the gumminess and the chewiness of the cheeses made using the EPS-producing cultures decreased with aging. The texture of the ripened low fat cheese made using EPS-producing cultures was described as chewy, springy, cohesive and smooth. The use of the ripening cultures resulted in the elimination of the bitter flavor defect which is a common problem in low fat Cheddar.展开更多
Cheddar and Kefalotyri cheese belong to the category of hard cheeses.Cheddar has an English origin,while Kefalotyri is a traditional cheese in Greece and a well-consumed dairy product in Cyprus.Discrimination of dairy...Cheddar and Kefalotyri cheese belong to the category of hard cheeses.Cheddar has an English origin,while Kefalotyri is a traditional cheese in Greece and a well-consumed dairy product in Cyprus.Discrimination of dairy products can be determined through several chemical methods.The aim of this study was to discriminate the samples of Cheddar and Kefalotyri cheese by analyzing various samples,from different brands.Two spectroscopic techniques namely proton nuclear magnetic resonance(1H-NMR)and Fourier-transformed infrared(FTIR)spectroscopy were chosen in order to chemically characterise the samples.The first step of the methodology was the freeze-drying process for lyophilisation of the samples.The number of samples reached 28,including 14 Cheddar samples and 14 samples of Kefalotyri cheese.After that,measurements for each sample have been obtained by FTIR(%transmittance-wavenumber in cm^-1)and ^1H-NMR(signal intensity-chemical shift in ppm)techniques.The data were analysed using SIMCA software.The proposed techniques along with chemometrics allow the discrimination of those two types of cheese.Both techniques employed are of significant importance,since they provide information about good classification of the samples when they are combined together.Interpretation of results and classification by using chemometric methods confirmed the different recipe of the two types of cheese.This study is the initial step of the future work.Future research will focus on discrimination based on the species’origin of milk of these and other cheese samples.展开更多
A cold-tolerant Lactiplantibacillus plantarum strain NMGL2,isolated from Inner Mongolian cheese,was studied as an adjunct culture to accelerate the ripening of Cheddar cheese.L.plantarum NMGL2 exhibited significantly ...A cold-tolerant Lactiplantibacillus plantarum strain NMGL2,isolated from Inner Mongolian cheese,was studied as an adjunct culture to accelerate the ripening of Cheddar cheese.L.plantarum NMGL2 exhibited significantly higher(37%-351%)proteolytic activity against peptide substrates(Lys-pNA and Gly-Pro-pNA)at low temperatures(10℃-20℃)and pH 5.0 compared to other L.plantarum strains(YW32,12-3,13-3)isolated from the same source.Inoculation of 7.0 log cfu/mL of L.plantarum NMGL2 with starter culture significantly altered the cheese microbiome during ripening,increasing both diversity and the relative abundance of non-starter lactic acid bacteria(L.plantarum,Lacticaseibacillus paracasei,Leuconostoc mesenteroides,Leuconostoc pseudomesenteroides),while reducing the abundance of Streptococcus thermophilus.This shift in microbial community composition is accompanied by accelerated cheese proteolysis,evidenced by a faster accumulation of short peptides(<1 kDa)and free amino acids in NMGL2-supplemented cheeses over 180 days of ripening.Enhanced proteolysis by NMGL2 resulted in a 1.49-fold increase in total volatile flavour compounds after 180 days,coinciding with the results of the sensory analysis that the odor intensity of Cheddar cheese significantly improved.Furthermore,RDA(redundancy analysis)and PCA(principal component analysis)correlation analysis revealed that the microbial and flavour profiles of 90-day NMGL2-treated cheese closely resembled those of 180-day control cheese.These findings highlight the potential of cold-tolerant L.plantarum NMGL2 as an adjunct culture to accelerate Cheddar cheese ripening.展开更多
基金financially supported by Beijing Municipal Commission of Education Co-Constructed Programand Chinese Universities Scientific Fund(2009-4-25)
文摘Proteolysis is one of the most important biochemical reactions during cheese ripening.Studies on the secondary structure of proteins during ripening would be helpful for characterizing protein changes for assessing cheese quality.Fourier transform infrared spectroscopy(FTIR),with self-deconvolution,second derivative analysis and band curve-fitting,was used to characterize the secondary structure of proteins in Cheddar cheese during ripening.The spectra of the amide I region showed great similarity,while the relative contents of the secondary structures underwent a series of changes.As ripening progressed,the α-helix content decreased and the β-sheet content increased.This structural shift was attributed to the strengthening of hydrogen bonds that resulted from hydrolysis of caseins.In summary,FTIR could provide the basis for rapid characterization of cheese that is undergoing ripening.
文摘Low fat cheeses often suffer from undesirable texture and flavor. The objective of this study is to improve the yield, texture, flavor and quality of low fat Cheddar cheese during ripening using exopolysaccharide-producing lactobacilli and ripening cultures. The article represents one of the first attempts to tackle both texture and flavor at the same time. The study reveals the effect of aging on the texture and flavor of low fat Cheddar cheese over a ripening period of six months. The cheese manufactured with a modified protocol using EPS-producing cultures and ripening cultures showed higher values for moisture content (45%) and yield (9.4%) when compared to cheese manufactured with the conventional procedure and without the addition of EPS-producing cultures and ripening cultures (37.7%) and (4.9%) respectively. The obtained results indicated a 70% decrease in the fat content of the cheese. Texture profile analysis (TPA) indicated that the hardness, the cohesiveness, the springiness, the gumminess and the chewiness of the cheeses made using the EPS-producing cultures decreased with aging. The texture of the ripened low fat cheese made using EPS-producing cultures was described as chewy, springy, cohesive and smooth. The use of the ripening cultures resulted in the elimination of the bitter flavor defect which is a common problem in low fat Cheddar.
文摘Cheddar and Kefalotyri cheese belong to the category of hard cheeses.Cheddar has an English origin,while Kefalotyri is a traditional cheese in Greece and a well-consumed dairy product in Cyprus.Discrimination of dairy products can be determined through several chemical methods.The aim of this study was to discriminate the samples of Cheddar and Kefalotyri cheese by analyzing various samples,from different brands.Two spectroscopic techniques namely proton nuclear magnetic resonance(1H-NMR)and Fourier-transformed infrared(FTIR)spectroscopy were chosen in order to chemically characterise the samples.The first step of the methodology was the freeze-drying process for lyophilisation of the samples.The number of samples reached 28,including 14 Cheddar samples and 14 samples of Kefalotyri cheese.After that,measurements for each sample have been obtained by FTIR(%transmittance-wavenumber in cm^-1)and ^1H-NMR(signal intensity-chemical shift in ppm)techniques.The data were analysed using SIMCA software.The proposed techniques along with chemometrics allow the discrimination of those two types of cheese.Both techniques employed are of significant importance,since they provide information about good classification of the samples when they are combined together.Interpretation of results and classification by using chemometric methods confirmed the different recipe of the two types of cheese.This study is the initial step of the future work.Future research will focus on discrimination based on the species’origin of milk of these and other cheese samples.
基金supported by the National Key Research and Development Program of China(2023YFF1103600)the National Center of Technology Innovation for Dairy(No.2022-KYGG-6).
文摘A cold-tolerant Lactiplantibacillus plantarum strain NMGL2,isolated from Inner Mongolian cheese,was studied as an adjunct culture to accelerate the ripening of Cheddar cheese.L.plantarum NMGL2 exhibited significantly higher(37%-351%)proteolytic activity against peptide substrates(Lys-pNA and Gly-Pro-pNA)at low temperatures(10℃-20℃)and pH 5.0 compared to other L.plantarum strains(YW32,12-3,13-3)isolated from the same source.Inoculation of 7.0 log cfu/mL of L.plantarum NMGL2 with starter culture significantly altered the cheese microbiome during ripening,increasing both diversity and the relative abundance of non-starter lactic acid bacteria(L.plantarum,Lacticaseibacillus paracasei,Leuconostoc mesenteroides,Leuconostoc pseudomesenteroides),while reducing the abundance of Streptococcus thermophilus.This shift in microbial community composition is accompanied by accelerated cheese proteolysis,evidenced by a faster accumulation of short peptides(<1 kDa)and free amino acids in NMGL2-supplemented cheeses over 180 days of ripening.Enhanced proteolysis by NMGL2 resulted in a 1.49-fold increase in total volatile flavour compounds after 180 days,coinciding with the results of the sensory analysis that the odor intensity of Cheddar cheese significantly improved.Furthermore,RDA(redundancy analysis)and PCA(principal component analysis)correlation analysis revealed that the microbial and flavour profiles of 90-day NMGL2-treated cheese closely resembled those of 180-day control cheese.These findings highlight the potential of cold-tolerant L.plantarum NMGL2 as an adjunct culture to accelerate Cheddar cheese ripening.
