Survey of nutrients and quality assessment of crab paste by 1H NMR spectroscopy and multivariate data analysis
SPECIAL TOPIC Omics in Marine Biotechnology
YE YangFang
1
ZHANG LiMin
0
TANG HuiRu
0
YAN XiaoJun
)
1
0
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences
, Wuhan 430071,
China
1
Key Laboratory of Applied Marine Biotechnology (Ningbo University)
, Ministry of Education, Ningbo 315211,
China
Crab paste is a traditional and popular food for people in the coastal area of China. Visual inspection is currently the only method of quality assessment. We developed a new analytical method of a comprehensive survey of nutrients and quality assessment for crab paste based on a combination of 1H NMR spectroscopy with multivariate data analysis. The aqueous extract of crab paste was dominated by amino acids, sugars, carboxylic acids, nucleotides and amines (including 19 first-time-reported compounds such as choline, uracil and guanosine). Two grades of crab paste had significant compositional differences in terms of amino acids, lactate, N-acetylglutamate, choline, dimethylamine, uridine, 1-methylnicotinamide and 2-pyridienmethanol. These results provided important information on the grade-dependence of crab-paste composition, and demonstrated that NMR-MDA was effective not only for the comprehensive survey of nutrients, but also for quality assessment of crab paste.
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Crab paste is a traditional and popular food in the coastal
area of China. It is a processed product of the swimming
crab Portunus trituberculatus. This is achieved by
saturation with salt and liquor, which maintains the characteristic
flavor, taste, and nutrients of the raw materials [1]. The
nutrient analysis has revealed that the swimming crab is rich in
proteins with complete amino acids, unsaturated fatty acid
and inorganic elements [2]. However, a quality standard of
crab paste based on the nutritional analysis has not been
developed. There is very scarce information on the nutrient
profiles, which determine the taste, appearance, and
nutritional quality. This is because comprehensive analysis of
the chemical compositions of seafood products is difficult
because of the complexity of the matrix and limited
analytical capacity of conventional chemistry methods. In fact, the
current method to classify the quality grades of crab paste is
dependent mainly on visual inspection.
To develop a more accurate, rapid and reliable analytical
method to assess seafood quality, we think nuclear magnetic
resonance (NMR) spectroscopy is suitable as an effective
non-invasive analytical tool that can provide comprehensive
information on the profiles of organic chemical metabolites.
More recently, a combination of 1H NMR spectroscopy
with multivariate data analyses has been established to
analyze the chemical components of food [3]. NMR technique
is intrinsically reproducible with rich information about
structure and rapidity without or simple preparation of complex
samples. Thus, it can be used to meet the increasing demands
of analyzing complex samples such as food with good
accuracy and consistency based on the entire chemical
composition of the samples [4,5]. Multivariate data analytical
techniques such as orthogonal projection to latent structure
discriminant analysis (OPLS-DA), a supervised multivariate
data analytical tool, can be used to provide group data
clus The Author(s) 2012. This article is published with open access at Springerlink.com
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tering by analyzing NMR-derived data [6]. Such technique
combinations have been applied successfully to assess the
quality of orange juice [7], beer [8], instant coffee [9], green
tea [10], pine-mushroom [11], Cheonggukjang [12], soy
sauce [13], milk [14], wine [15], beef [16] and honey [17].
In the present study, we systematically analyzed the
chemical compositions of crab paste using high-resolution
NMR spectroscopy coupled with multivariate data analyses.
The study objectives were to: (1) validate the potential of a
metabolomic approach in the survey of nutrients of marine
products; (2) investigate all of the detectable components in
aqueous extracts from crab paste; and (3) define the
statistically significant metabolomic features that could be used
to differentiate between two grades of crab paste.
Materials and methods
Acetonitrile, NaH2PO42H2O and K2HPO43H2O were
purchased from Guoyao Chemical Co. Ltd. (Shanghai, China),
and all were of analytical grade. D2O (99.9%) and sodium
3-trimethylsilyl [2,2,3,3-d4] propionate (TSP) were
purchased from SigmaAldrich (St. Louis, MO, USA).
Phosphate buffer (K2HPO4/NaH2PO4, 0.1 mol L1, pH 7.4),
containing 10% D2O (v/v) and 0.005% TSP (w/v), was
prepared in H2O [18].
Grade-3A and grade-2A samples of crab (Portunus
trituberculatus) paste (six bottles in each group) were purchased
from a supermarket in Ningbo, China. According to the
ingredients marked on the packaging, sucrose and glutamate,
as food additives, were supple (...truncated)