|
|
|
|
J. T.
"STUBBY" PARKER CHAIR IN DAIRY FOODS W.
James Harper RESEARCH:
WARMED
OVER FLAVOR IN COOKED BEEF: GC/MS
studies have shown that hexanal, which is the primary marker for warmed over
flavor, is not the primary cause of the flavor. Decendienal formation, with a 1000 fold lower threshold
flavor is formed after 24-48 hours and coincides with the first detectable
sensory evaluation of the warmed over flavor.
Hexanal reaches 90% of its maximum value in 3-6 hours of cold storage
after initial cooking. (Zohair) Projects in Progress:
ELECTRONIC NOSE APPLICATIONS: (Jim Harper) For
the past two years, the work on the electronic nose has shifted to the use of
headspace and the mass spectrometer. This
provides a means for obtaining an understanding of the chemistry behind the
differentiation of aromas. The mass
spectrometer can be operated in electronic ionization (EI) or in chemical
ionization (CI) modes. EI provides
extensive fragmentation and provides on an understanding of the function groups
involved. Chemical ionization is
used primarily for conformation of molecular weights of compounds and results in
a much lower level of fragmentation. Study
has been initiated to develop a mass spectroscopy library of compounds thought
to differentiate the aroma of different cheeses.
No such library exists at the present time.
SWISS
CHEESE RESEARCH [Researchers – Cheryl Wick,
Josephine Kuo, Julie Jenkins,
Maria Ruhlman, Nurdan Kocaoglu-Vurma and
Olga Anngraeni] Most
of this research is under the direction of Polly Courtney:
Development Of A Swiss cheese Make Procedure For Small Scale Manufacture
(Investigator – Cheryl Wick)
Work is in progress to adapt commercial cheese manufacturing procedures
to small-scale production (5 lbs/vat). This
will provide a means of evaluating the effect of variables in manufactures, such
as the addition of milk solids, that will be more meaningful that the normal
procedure by Baby Swiss cheese. A
procedure has been developed, starting with a liter of milk that produces a 100
cheese that produces Swiss cheese flavor and eyes.
Comparison
Of GC Analysis Of Acetic And Propionic Acid Contents With Sensory Values Swiss (Investigator: Josephine Kuo)
A lexicon of twenty-three descriptors has been developed in collaboration
with Dr. Mary Anne Drake of NCSU to provide a uniform set of descriptors that
will provide for a uniform lexicon for the sensory evaluation of Swiss cheese. This included the deletion and additions of descriptors used
in the Cheddar cheese lexicon. Generally data obtained by GC analyses for
fatty acids did not agree with the sensory scores for the acetic acid and
propionic descriptors. However, for
the one cheese that had a free fatty acid note also hade the highest level of
butyric acid and high levels of C-6 and C-8 fatty acids. Determination
of the role of non-starter lactic acid bacteria in Swiss cheese quality. (Investigator:
Nurdan Kocaoglu-Vurma) Non-starter
lactic acid bacteria (NSLAB) are known to be important in the ripening of
Cheddar cheese and may have either a positive of negative effect on the ripening
process. These organisms are
primarily lactobacilli. Their role in Swiss cheese has not been established. Investigation has shown that in mature Swiss cheese the
lactobacillus used in the starter for Swiss cheese (Lactobacillus helveticus)
disappears during the first 30 day of ripening and is replaced be from 3-12
different NSLAB. The significance
of these organisms to cheese quality is under investigation.
Effect of milk solids addition
on Swiss cheese quality. (Investigator:
Maria Ruhlman A
scientific study on adding different levels of milk protein has been initiated.
Problems with contamination of slurries has caused a shift in the
experimental plan to do screening experiments with the manufacture of pilot
plant cheese with the addition of non fat dry milk and milk protein
concentrates. The cheese are being
made using the same S. thermophilus and L. helveticus and different
propionibacteria to determine if the solids addition will affect the cheese
characteristics using different strains of propionibacter.
Increasing
Swiss cheese moisture using a polysaccharide-producing starter culture
(Olga Anngraeni)
Preliminary work with sterile cheese slurries has suggested a 1.0
increase in yield. The work will
now be directed to pilot plant trials. EFFECT
OF WHEY PROTEIN COMPONENTS ON THE GLUTATHIONE CONTENT OF PROSTATE NORMAL AND
CANCER CELLS IN RELATION TO PROTECTION AGAINST STRESS. [Investigator: Kyle
Kent]
Prostate
cancer is the second leading cause of cancer death among men in the United
States. Studies suggest that dietary whey proteins may reduce the risk for
certain cancers by increasing cellular levels of the antioxidant glutathione.
Whey proteins are rich in cystine, the hypothesized rate-limiting amino acid for
glutathione synthesis; therefore, supplementation with whey protein isolate may
represent a means to increase glutathione synthesis within the prostate and
protection against oxidative stress. Cysteine
is the rate-limiting amino acid for synthesis of the ubiquitous antioxidant
glutathione (GSH). ovine whey proteins are rich
in cystine, the di-sulfide form of the amino acid cysteine. The objective of
this study was to determine whether enzymatically hydrolyzed
whey protein isolate (WPI) could increase intracellular GSH concentrations and
protect against oxidant- induced cell death
in a human prostate epithelial cell line (designated RWPE-1). Treatment of
RWPE-1 cells with hydrolyzed WPI (500 mg/ml) is significantly increased intracellular GSH by 64%, compared
with control cells receiving no hydrolyzed WPI (P<0.05). A similar increase
n GSH was observed with N-acetylcysteine (500 mm), a cysteine-donating compound
known to elevate intracellular GSH. In
contrast, treatment with hydrolyzed sod um caseinate (500 mg/ml), a cystine-poor
protein source, did not significantly elevate intracellular
GSH. Hydrolyzed WPI (500 mg/ml) significantly protected RWPE-1 cells from
oxidant-induced cell death, compared with
controls receiving no WPI (P<0.05). The results of this study indicate that
WPI can increase GSH synthesis and protect against
oxidant- induced cell death n human prostate cells.. Studies
have been extended to the effect of sphingolipids on both normal and cancerous
prostate cells. Preliminary work
with ceramides (metabolite of sphingolipids) cause death of cancerous, but not
normal prostate cells. CHEDDAR CHEESE – TRACE POLYFUNCTIONAL THIOL COMPOUNDS: Researcher: Joe Kleinhenz]] The
exact chemical nature of the flavor of Cheddar cheese remains poorly understood,
even after more that 100 years of research. A new project has been initiated to
try to determine if there are specific compounds that are responsible for the
"Cheddar" flavor. The hypothesis is that there remain unidentified,
very labile, compounds in Cheddar cheese that haven't been discovered previously
that that these are the "missing links" in Cheddar cheese flavor.
A
method has been developed that permits the isolation of flavor compounds from
aged Cheddar cheese that are present in parts per trillion, and that have flavor
threshold values in the same range. The
method has been shown to detect only mercaptans and does not detect ppm
concentrations of thioethers, thiazoles or aliphatic acids and aldehydes.
Analysis of 6 sharp Cheddar
cheese has shown the presence of from 20-40 polyfuctional thiol compounds in ppb
concentrations with qualitative and quantitative differences that can be related
back to the flavor characteristics of the cheese.
Fifteen compounds were tentatively identified including:
3-merpto- 2-methyl butanal (broth, cheese), 4-mercto-pentan-2-ol (back
current, catty), 3-mercapto-2-butylpropanal (pungent).
The different thiol compounds have threshold levels in the ppt and widely
different sensory descriptors. Work
is in progress to determine that statistical relationship between the type and
concentrations of these trace thiol compounds to sensory descriptors of the
cheeses. DAIRY
FARM MILKING PARLOR PRACTICES: (Investigator:
Jennifer Diehl)
The size of dairy herds in Ohio has increase significantly in recent
years, so that the average herd size is 60 cows with >75 herds ranging in
size from 300-2000 cows. This has created environmental concerns and it has been shown
that milk parlor waste water can contributed up to 20% of the total waste volume
going to lagoons. A survey has been
made of 85 herds of over 300 cows to establish milking parlor practices.
Ten of these farms will be visited to obtain wastewater from the milk
parlors and to characterize these for composition, pH and COD.
Attention will then be directed to means of reducing the impact of the
milk parlor wasted to the environment. Nana-filtration
will be one approach to be considered for wastewater and COD reduction. HIGH
PRESSURE TREATMENT OF PASTEURIZE MILK: (Investigator: Emily Adams)
The limitation of shelf life of pasteurized milk has been the outgrowth
of psychotropic microorganisms that arise primarily for post pasteurization of
milk. The ability of high pressure
processing (HPP) to extend the shelf life of packaged pasteurized milk is under
investigation. Results to date
suggest that the shelf life of 2% milk can be extended up to 20 days longer that
the control pasteurized milk with very minor changes in physical properties.
The application of HPP to chocolate milk has been less successful. FACTORS
AFFECTING THE FLAVOR OF UHT MILK IN PPT BOTTLES: This
is a new project to be initiated in July and will be a continuation of a CIFT
project on UHT milk. No
investigator has been assigned to the project at this time. USE
OF PEF TO CONTROL THE MICROFLORA IN HIGH PROTEIN, HIGH SOLIDS WHEY PROTEIN
CONCENTRATE: (investigator:
Dr. Josephine Kuo)
A new project that was activated on April 1, 2003 to determine if PEF can
be used as a means of reducing the microflora in the retentate of WPC without
altering the functional properties. Initial
studies have been limited to characterizing the physical properties of
reconstituted neutralize and un-neutralized 80% WPC at concentrations ranging
from 17-23%. It has been shown that
the maximum field strength that can be used is 40, 37 and 32 KV/cm at 400 pulses
per second and a pulse width of 2.5 microseconds. Work is just starting to
determine the reduction that can be achieved against the primary organisms
causing problems in production of the high protein WPC (S. thermophilus). CHARACTERIZATION
OF HEAT RESISTANT STEPTOCOCCUS THERMOMPHILUS: (Investigator:
Rory Delainey) Heat
resistant Streptococcus thermophilus have been isolated from membrane whey
protein concentrate retentate that was ulterfiltered at 50 deg. C.
These organisms may have value in dairy products, such as yogurt, and are
being evaluated for genetic variance, heat resistance and acid production in
milk. Project was initiated April
1, 2003 Teaching:
The Chair has cut back on
teaching and now has responsibility only for FST 650 - Food Product Development.
This year he will be assisting Dr. Polly Courtney who will be teaching FST 401
– Introduction to Food Processing and Dr. Sheryl Barringer, who will be
teaching FST 696 – Technical Problem Solving. EXTENSION:
Major extension functions
included the annual Food and Dairy Conference and support of various food
factories in assisting in problem solving and extension related research. 2003
PUBLICATIONS:
OTHER
- papers in Reference Manual for U.S. whey and lactose products, April
2003 Harper,
W. J. 2003. Biological Properties of Whey
Components. In Reference Manual for U.S. Whey and Lactose Products.
Ed. G. Miller. U.S. Dairy Export Council, Washington DC pp68-69. Gerdes, S.K, and
Harper, W. J. 2003 Whey Proteins and Cardovascular Health. In Reference Manual
for U.S. Whey and Lactose Products Ed.
G. Miller. U.S. Dairy Export Council, Washington DC pp68-69. Function
food web page: A
Web Page on Dairy Functional Foods is being updated once a year. It can be
viewed in the UPDATE section of the Parker Chair Web Page towards the end of the
web page – under PRESENTATION.
http://www.fst.ohio-state.edu/People/HARPER/Functional-foods/Functional-Foods.htm
|
|
|