Biology Reference
In-Depth Information
Abbreviations
BMD Bone mineral density
BUA Bone ultrasound attenuation
QUI
Quantitative ultrasound index
SOS
Speed of sound
28.1
Introduction
Assessment of fish thawing is usually made through direct inspection by experi-
enced technicians; however, in some cases, the assessment may be difficult or
impossible, particularly in prepared and transformed products (fillets, tails, slices,
etc.). Imaging diagnostic techniques may provide noninvasive morphological and
structural information on analyzed tissues. Currently, diagnostic imaging has been
used to examine certain characteristics of parmigiano reggiano cheese and raw ham
(prosciutto crudo di Parma) (Orlandini et al.
1985
) to evaluate food adulteration,
identify fish species (Anastasio et al.
2002
; Anastasio et al.
2004
; Cortesi
2005
), and
verify food freshness (Meomartino et al.
2006
). In fish products, ultrasonography
(US) was demonstrated to be a rapid method to assess (a) changes related to storage
conditions, (b) meat and fat tissue distribution, and (c) anatomical marks useful to
prove fraud (Anastasio et al.
2004
; Cortesi
2005
; Meomartino et al.
2006
). It is well
known that, following freezing and thawing, fish soft tissues undergo ultrastructural
changes characterized by sarcolemmal damage and clear interfibrillar spaces filled
by intracellular fluids (Ayala et al.
2005
). As a consequence, soft tissues become
more “rigid,” which improves impedance and can be determined via increased
reflection and speed of the ultrasounds during their progression through the tissues.
The purpose of the present study was to assess whether US is a valuable method to
assess changes in thawed sea bream (
Sparus aurata
) tissues.
28.2 Materials and Methods
The study was organized in two steps. In the first step, the epiaxial muscles of 15 sea
breams, weighing 400-500 g and coming from an offshore fish farm in the Pozzuoli
Gulf (Naples), were examined using US. To make the US protocol simpler and
more reproducible, three transverse scans were made on each subject: the first at the
middle of the lateral line and the others at the middle of the cranial and caudal
halves of the lateral line. The US study was performed on five fresh (8 h after
capture) sea breams, five subjects after a first thawing, and five subjects after
