Influence of Carboxypeptidases on Cocoa Specific Aroma Precursors and Methylpyrazines in Under-Fermented Cocoa Beans
A study on the influence of two carboxypeptidases on cocoa specific aroma precursors and methylpyrazines in under..fermented cocoa beans was carried out. Cocoa beans, which were fermented for three days using wooden box were used as samples. The beans were powdered and then incubated at 45°C for...
Saved in:
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English English |
| Published: |
2003
|
| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/8497/1/FSMB_2003_1_IR.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| id |
my-upm-ir.8497 |
|---|---|
| record_format |
uketd_dc |
| institution |
Universiti Putra Malaysia |
| collection |
PSAS Institutional Repository |
| language |
English English |
| advisor |
Selamat, Jinap |
| topic |
Carboxypeptidases Fermented foods |
| spellingShingle |
Carboxypeptidases Fermented foods Ikrawan, Yusep Influence of Carboxypeptidases on Cocoa Specific Aroma Precursors and Methylpyrazines in Under-Fermented Cocoa Beans |
| description |
A study on the influence of two carboxypeptidases on cocoa specific aroma
precursors and methylpyrazines in under..fermented cocoa beans was carried
out. Cocoa beans, which were fermented for three days using wooden box
were used as samples. The beans were powdered and then incubated at 45°C
for 6, 12, 24 and 48 h. Protein content, carboxypeptidase activity, cocoa
storage protein, free amino acids, peptide profiles and methylpyrazines
concentration were determined. Commercial carboxypeptidase B from
porcine and carboxypeptidase Y from baker's yeast were used separately for
digestion of cocoa storage protein. Protein content decreased during 3 days
of fermentation. Three major bands of cocoa storage protein were found
using SDS-P AGE. Carboxypeptidase activity increased after one day, but later decreased between two and three days of fermentation. During three
days of fermentation, free amino acids increased and about 50 to 62% of
hydrophobic free amino acids were produced. Hydrophobic peptides in
unfermented cocoa beans were considerably higher as compared to underfermented
beans. However, their peptide profiles were very similar for all
samples taken at one to three days of fermentation. The concentration of 2,5-
dimethyl-, 2,3,5-trimethyl- and 2,3,5,6-tetramethylpyrazines were low after
one day and increased during two to three days of fermentation.
The degradation of cocoa storage protein from the samples treated with 5 %
and 10% of carboxypeptidase B and carboxypeptidase Y revealed similar
peptide bands with those of the untreated samples. Hydrophobic free amino
acids (alanine, valine, isoleucine, leucine,phenylalanine and tyrosine) were
predominantly produced in the samples treated with 5% and 10% of
carboxypeptidase B and Y. The pep tides profile were very similar with those
of the control (well fermented beans). Digestion with carboxypeptidase B and
carboxypeptidase Y did not have a significant effect on the concentration of
2,5-dimethyl-, 2,3,5-trimethyl- and 2,3,5,6-tetramethylpyrazines.
Concentrations of acidic amino acid (aspartic, glutamic), hydrophobic amino
acids (leucine, alanine, phenylalanine, tyrosine, valine and isoleucine), others
(proline, methionine, cysteine, tryptophane, lysine, serine, glysine, histidine,arginine and threonine) and total of amino acids in the untreated adn treated
samples with 5% and 10% of carboxypeptidase B and carboxypeptidase Y
were significant decreased by roasting at 150°C for 15 min. The proportions
of peptides also decreased upon roasting. Peptide profiles revealed very
similar chromatogram with those of untreated sample. The concentration of
2,3,5,6-tetramethylpyrazine was significantly higher for samples treated with
carboxypeptidase B compared to 2,5-dimethyl- and 2,3,5-trimethylpyrazine.
However, the concentration of 2,3,S-trimethylpyrazine was the highest
(1727.86 µg 100g-1) in the sample with carboxypeptidase B that had been
incubated for 24 h. Cocoa liquor made from under-fermented cocoa beans
treated with carboxypeptidase B and carboxypeptidase Y were more bitter,
astringent, acidic, higher in off-flavour and possessed weaker cocoa flavour
compared to the reference (Ghanaian cocoa) sample. There were no
significant differences (p>0.05) among samples treated with 5% and 10% of
carboxypeptidases B and Y; however, there was significant correlation
(P<0.05) between methylpyrazines and cocoa flavour attribute and also with
hydrophobic free amino acids in the samples treated with both enzymes.
The overall findings indicate that carboxypeptidase B from porcine pancreas
was efficient for the formation of cocoa specific aroma precursors. |
| format |
Thesis |
| qualification_level |
Doctorate |
| author |
Ikrawan, Yusep |
| author_facet |
Ikrawan, Yusep |
| author_sort |
Ikrawan, Yusep |
| title |
Influence of Carboxypeptidases on Cocoa Specific Aroma Precursors and Methylpyrazines in Under-Fermented Cocoa Beans |
| title_short |
Influence of Carboxypeptidases on Cocoa Specific Aroma Precursors and Methylpyrazines in Under-Fermented Cocoa Beans |
| title_full |
Influence of Carboxypeptidases on Cocoa Specific Aroma Precursors and Methylpyrazines in Under-Fermented Cocoa Beans |
| title_fullStr |
Influence of Carboxypeptidases on Cocoa Specific Aroma Precursors and Methylpyrazines in Under-Fermented Cocoa Beans |
| title_full_unstemmed |
Influence of Carboxypeptidases on Cocoa Specific Aroma Precursors and Methylpyrazines in Under-Fermented Cocoa Beans |
| title_sort |
influence of carboxypeptidases on cocoa specific aroma precursors and methylpyrazines in under-fermented cocoa beans |
| granting_institution |
Universiti Putra Malaysia |
| granting_department |
Food Science and Technology |
| publishDate |
2003 |
| url |
http://psasir.upm.edu.my/id/eprint/8497/1/FSMB_2003_1_IR.pdf |
| _version_ |
1794018760940584960 |
| spelling |
my-upm-ir.84972024-01-29T03:34:21Z Influence of Carboxypeptidases on Cocoa Specific Aroma Precursors and Methylpyrazines in Under-Fermented Cocoa Beans 2003-06 Ikrawan, Yusep A study on the influence of two carboxypeptidases on cocoa specific aroma precursors and methylpyrazines in under..fermented cocoa beans was carried out. Cocoa beans, which were fermented for three days using wooden box were used as samples. The beans were powdered and then incubated at 45°C for 6, 12, 24 and 48 h. Protein content, carboxypeptidase activity, cocoa storage protein, free amino acids, peptide profiles and methylpyrazines concentration were determined. Commercial carboxypeptidase B from porcine and carboxypeptidase Y from baker's yeast were used separately for digestion of cocoa storage protein. Protein content decreased during 3 days of fermentation. Three major bands of cocoa storage protein were found using SDS-P AGE. Carboxypeptidase activity increased after one day, but later decreased between two and three days of fermentation. During three days of fermentation, free amino acids increased and about 50 to 62% of hydrophobic free amino acids were produced. Hydrophobic peptides in unfermented cocoa beans were considerably higher as compared to underfermented beans. However, their peptide profiles were very similar for all samples taken at one to three days of fermentation. The concentration of 2,5- dimethyl-, 2,3,5-trimethyl- and 2,3,5,6-tetramethylpyrazines were low after one day and increased during two to three days of fermentation. The degradation of cocoa storage protein from the samples treated with 5 % and 10% of carboxypeptidase B and carboxypeptidase Y revealed similar peptide bands with those of the untreated samples. Hydrophobic free amino acids (alanine, valine, isoleucine, leucine,phenylalanine and tyrosine) were predominantly produced in the samples treated with 5% and 10% of carboxypeptidase B and Y. The pep tides profile were very similar with those of the control (well fermented beans). Digestion with carboxypeptidase B and carboxypeptidase Y did not have a significant effect on the concentration of 2,5-dimethyl-, 2,3,5-trimethyl- and 2,3,5,6-tetramethylpyrazines. Concentrations of acidic amino acid (aspartic, glutamic), hydrophobic amino acids (leucine, alanine, phenylalanine, tyrosine, valine and isoleucine), others (proline, methionine, cysteine, tryptophane, lysine, serine, glysine, histidine,arginine and threonine) and total of amino acids in the untreated adn treated samples with 5% and 10% of carboxypeptidase B and carboxypeptidase Y were significant decreased by roasting at 150°C for 15 min. The proportions of peptides also decreased upon roasting. Peptide profiles revealed very similar chromatogram with those of untreated sample. The concentration of 2,3,5,6-tetramethylpyrazine was significantly higher for samples treated with carboxypeptidase B compared to 2,5-dimethyl- and 2,3,5-trimethylpyrazine. However, the concentration of 2,3,S-trimethylpyrazine was the highest (1727.86 µg 100g-1) in the sample with carboxypeptidase B that had been incubated for 24 h. Cocoa liquor made from under-fermented cocoa beans treated with carboxypeptidase B and carboxypeptidase Y were more bitter, astringent, acidic, higher in off-flavour and possessed weaker cocoa flavour compared to the reference (Ghanaian cocoa) sample. There were no significant differences (p>0.05) among samples treated with 5% and 10% of carboxypeptidases B and Y; however, there was significant correlation (P<0.05) between methylpyrazines and cocoa flavour attribute and also with hydrophobic free amino acids in the samples treated with both enzymes. The overall findings indicate that carboxypeptidase B from porcine pancreas was efficient for the formation of cocoa specific aroma precursors. Carboxypeptidases Fermented foods 2003-06 Thesis http://psasir.upm.edu.my/id/eprint/8497/ http://psasir.upm.edu.my/id/eprint/8497/1/FSMB_2003_1_IR.pdf text en public doctoral Universiti Putra Malaysia Carboxypeptidases Fermented foods Food Science and Technology Selamat, Jinap English |