Biomedical Engineering Reference
In-Depth Information
of food products. Ultrasound imparts positive effects in food processing such as
improvement in mass transfer, food preservation, assistance of thermal treatments
and manipulation of texture and food analysis (Knorr et al.
2011
). Based on fre-
quency range, the applications of ultrasound in food processing, analysis and qual-
ity control can be categorized into low and high energy. Low power ultrasound has
frequencies higher than 100 kHz at intensities below 1 W cm
2
, which can be utilized
for non-invasive analysis and monitoring of various food materials including meat
and meat products during processing and storage to ensure high quality and safety.
Low power ultrasound has been used for evaluating the composition of raw and
fermented meat products, fi sh and poultry (Awad et al.
2012
). High power ultra-
sound uses intensities higher than 1 W cm
2
at frequencies between 20 and 500 kHz,
which are disruptive and induce effects on the physical, mechanical or chemical/
biochemical properties of foods and meat products. These effects are promising in
food processing, preservation and safety. Thus high power ultrasound can be uti-
lized as an alternative to conventional food processing operations to control micro-
structure and modify textural characteristics, in emulsifi cation, improvement of
functional properties of different food proteins, inactivation or acceleration of enzy-
matic activity to enhance shelf life and quality of food products, freezing, thawing,
cooking, pasteurization, tenderization etc. The advantages of the technology are
versatile and profi table to the food industry, though more research efforts are still
needed to design and develop effi cient power ultrasonic systems that support large
scale operations and that can be adapted to various processes (Gallego-Juárez et al.
2010
). Till now in meat industry, high power ultrasound has found its application in
tenderization, thawing, cooking and sterilization of various products.
Application in raw products
: Meat tenderness is one of the most important quality
attributes affecting consumer satisfaction and positive perception. Inconsistency in
meat tenderness has been rated as one of the major problems faced by the meat
industry. Tenderness is infl uenced by composition, structural organization and the
integrity of skeletal muscle (Jayasooriya et al.
2004
). The traditional method used
for meat tenderization is mechanical pounding, which makes poorer quality meat
more palatable. Use of proteolytic enzymes such as papain, bromelain, and fi cin, to
improve meat tenderness lacks uniformity. In this regard the use of ultrasound to
improve meat tenderness can be made which causes physical disruption of materials
through cavitation related mechanisms such as high shear, pressure and temperature
and formation of free radicals (Jayasooriya et al.
2007
). Ultrasound induces cell
membrane disruption that could increase meat tenderness either directly, through
the physical weakening of muscle structure, or indirectly, by the activation of prote-
olysis either by release of cathepsins from lysosomes and/or of Ca
++
ions from intra-
cellular stores so that it may activate the calpains (Boistier-Marquis et al.
1999
).
Improvement in meat tenderness through ultrasound can reduce the intensity and
period of cooking to get the fi nal product. It is possible to reduce traditional heat
treatment by 50 % by using high-energy ultrasound (Pagán et al.
1999
).
Application of ultrasound for the thawing of meat and fi sh indicated that accept-
able ultrasonic thawing can be achieved at frequencies around 500 kHz, which con-
formed to a relaxation mechanism (Miles et al.
1999
). Acoustic thawing can shorten
