Numerous investigations have been made on the contribution of
butter cultures to the flavor of cultured cream butter, but production
of uniform cultured cream butter has not been possible in industry.
Therefore, it was desirable to investigate in detail the qualitative
and quantitative chemistry of the flavor of high quality butter cultures,
and to examine more closely some of the aspects of flavor
production by butter culture organisms.
Volatile flavor components of high quality butter culture and
control heated milk were isolated from intact samples by means of
a specially designed low-temperature, reduced-pressure steam distillation
apparatus. Most of the flavor compounds present in the resulting
distillate fractions were tentatively identified by gas chromatographic
relative retention time data. Flavor concentrates obtained
by ethyl ether extractions of aqueous distillates were also separated by temperature-programmed, capillary column gas chromatography,
and the effluent from the capillary column was analyzed by a fast-
scan mass spectrometer. Many of the flavor compounds in the flavor
concentrates were positively identified by correlation of mass spectral
and gas chromatographic data. In addition, supporting evidence
for the identification of some flavor components was obtained through
the use of qualitative functional group reagents, derivatives and headspace
gas chromatography.
Compounds that were positively identified in butter culture include
ethanol, acetone, ethyl formate, methyl acetate, acetaldehyde,
diacetyl, ethyl acetate, dimethyl sulfide, butanone, 2-butanol,
methyl butyrate, ethyl butyrate, methane, methyl chloride, carbon
dioxide and methanol; also included were 2-pentanone, 2-heptanone,
acetoin, formic acid, acetic acid, lactic acid, 2-furfural, 2-furfurol,
methyl hexanoate, ethyl hexanoate, 2-nonanone, 2-undecanone,
methyl octanoate and ethyl octanoate. Compounds that were tentatively
identified in butter culture include hydrogen sulfide, methyl
mercaptan, n-butanal, n-butanol, 2-hexanone, n-pentanal, n-pentanol,
2-mercaptoethanol, n-butyl formate, n-butyl acetate,
2-methylbutanal, 3-methylbutanal, methylpropanal, methyl heptanoate,
n-octanal, 2-tridecanone, methyl benzoate, methyl nonanoate,
ethyl nonanoate, ethyl decanoate, methyl dodecanoate, ethyl dodecanoate,
delta-octalactone and delta-decalactone.
Compounds that were positively identified in control heated milk
include acetaldehyde, ethyl formate, ethyl acetate, 2-heptanone,
2-furfural, 2-furfurol, 2-nonanone, 2-undecanone, ethyl octanoate
and methyl decanoate. Compounds that were tentatively identified in
control heated milk include dimethyl sulfide, hydrogen sulfide, ammonia,
methyl mercaptan, methyl acetate, acetone, methanol, butanone,
butanal, n-butanol, methyl butyrate, ethyl butyrate, 2-pentanone,
2-hexanone, 2-mercaptoethanol, 2-furfuryl acetate, ethyl
hexanoate, methyl heptanoate, 2-tridecanone, ethyl decanoate, ethyl
dodecanoate, delta-octalactone and delta-decalactone. The data indicated
that the qualitative flavor composition of control heated milk
and butter culture were very similar. Diacetyl, ethanol, 2-butanol
and acetic acid were noted to be consistently absent in the data for
the control heated milk. Other compounds were not observed in the
heated milk fractions, but were also absent from some of the culture
fractions. This was attributed to their presence in low concentrations,
chemical instability or inefficient recovery.
A modified 3-methyl-2-benzothiazolone hydrazone spectrophotometric
procedure was adapted for the determination of acetaldehyde
produced in lactic starter cultures. The procedure was applied in
conjunction with diacetyl measurements in studying single- and
mixed-strain lactic cultures. The diacetyl to acetaldehyde ratio was
found to be approximately 4:1 in desirably flavored mixed-strain butter cultures. When the ratio of the two compounds was lower
than 3:1 a green flavor was observed. Acetaldehyde utilization at
21°C by Leuconostoc citrovorum 91404 was very rapid in both acidified
(pH 4.5) and non-acidified (pH 6.5) milk cultures. The addition
of five p.p.m. of acetaldehyde to non-acidified milk media prior to
inoculation greatly enhanced growth of L. citrovorum 91404 during
incubation at 21°C. Combinations of single-strain organisms demonstrated
that the green flavor defect can result from excess numbers
of Streptococcus lactis or Streptococcus diacetilactis in relation
to the L. citrovorum population.
Diacetyl, dimethyl sulfide, acetaldehyde, acetic acid and carbon
dioxide were found to be "key" compounds in natural butter culture
flavor. Optimum levels of these compounds in butter culture were
ascertained by chemical or flavor panel evaluations. On the basis of
these determinations, a synthetic butter culture prepared with heated
whole milk and delta-gluconolactone (final pH 4.65) was flavored with
2.0 p.p.m. of diacetyl, 0.5 p.p.m. of acetaldehyde, 1250 p.p.m. of
acetic acid, 25.0 p.p.b. of dimethyl sulfide and a small amount of
sodium bicarbonate for production of carbon dioxide. The resulting
synthetic butter culture exhibited the typical aroma, flavor and body
characteristics found in natural high quality butter cultures, except
that the delta-gluconolactone was found to contribute an astringent
flavor. / Graduation date: 1965
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/26780 |
| Date | 14 May 1965 |
| Creators | Lindsay, Robert C. (Robert Clarence), 1936- |
| Contributors | Day, Edgar Allen |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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