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This industry/academia project was the first instance of Rutgers University’s being a paid
subcontractor to a private research company, and required a new type of contract.
Descriptions of major work
A New Paradigm of Deep-Fat Frying
Deep-fat frying is one of the most widely used methods of food production, and is practiced all
over the world. It is a
$75 billion a year
industry
in
the U.S. alone, and estimated
to be
twice
that worldwide.
An extremely wide variety of types of foods are fried and oil blanched, and frying
fats and oils are valuable and ever-more-costly agricultural commodity products. Extensive
research is being done in the U.S. and abroad on new oilseed varieties, genetically enhanced
oils, and processes and procedures to improve the nutritional profile, stability, and other
important properties of fats and oils used for food, and, in particular, for deep frying. In addition,
the quality, safety, nutritional and aesthetic values of many agricultural products - the foods fried
- are affected significantly by the frying process. The proper conduct of frying operations is
essential for food quality, safety, nutrition, and economics. Until now, it has been largely an art.
Dr. Michael Blumenthal has developed a powerful new scientific understanding of the dynamic
forces and factors that affect frying processes, and his research has led to
a new paradigm.
He
has approached the problem of the degradation of edible fats and oils during frying processes
from a
physical chemistry
/ engineering
/ systems perspective,
focusing on heat and mass
transfer,
going
beyond
the
traditionally-studied
organic chemistry
of
frying
oils.
His
research explores the entire frying
system
and the
interactions
between frying fats/oils and the
foods fried, the equipment and processing aids used, ingredients coming in, and the complex
chemistry at work between the heated surfaces, the degrading oil, leachates from the food,
entrained and reactive oxygen, and the constantly changing surface and interior of the
dehydrating food.
Dr. Blumenthal
has
proposed
(and
subsequent
research has
confirmed)
a new paradigm
of
surfactancy
as
the mediator
of
heat
transfer
between
frying
oil
and largely
aqueous
food.
The theory states "Surfactants are responsible for the surface and interior differences in
fried foods, as induced by aging oils." Using the systems approach and analyzing thousands of
samples, Dr. Blumenthal's laboratory established a large database from which he deduced a
simple mathematical relationship between the concentration of surfactants and the variations in
food quality typically seen in food production and food service. Surfactants increase as oil is used
and degrades. Control of surfactants enables proper cooking and optimization of food quality,
food stability, oil economics, and system productivity.
However, in degrading oil, as surfactant concentrations are increasing, leading to the oil "wetting"
the food, the specific heat of the oil is increasing from that of fresh oil (linearly) with the
accumulation of polymer species, which form due to oxidation and thermally abusive conditions.
This increased specific heat causes poor cooking due to insufficient heat being available in the oil
on the wetted surface. The formation and accumulation of smaller molecular species such as free
fatty acid increases thermal conductivity, which factor controls the rate of replenishment of
energy to oil at the food's surface. Without proper heat transfer into the interior of the food, even
the microbial safety of fried foods such as chicken is compromised.
The Gaussian curve that describes the relationship between the surfactant and polymer and
other polar material concentrations and perceptible food quality has been named the
Frying
Quality Curve,
and it portrays regions corresponding to initialization, normalization, optimization,
AOAC OMB Teleconference Materials
163
11/09/2016