15 Applications: Food Science
353
15.8 Honey
Initial NIR spectroscopy studies on honey mainly comprised the determination of
its chemical composition [48]. Honey is a completely natural, high-value product
comprising simple carbohydrates with a distinct sucrose–glucose–fructose profile
and water. Cane invert sugar preparations are often prepared to mimic this profile
and added to pure honey. Addition of such preparations is usually difficult to detect.
Differences in floral species, maturity, environment, processing and storage techniques contribute to the natural variability of honey and thus the complexity of
detecting honey adulteration.
The use of NIR spectroscopy and PLS-DA to detect adulterated honey has been
demonstrated [49]. The addition of fructose and glucose could be detected with a
high degree of success (99%). Similarly, the pure honey could be accurately identified
(96%). The importance of temperature control during NIR analysis was, however,
stressed. When SIMCA was evaluated as a discrimination technique [50], the adulterated honey could be 100% correctly identified compared to only 90% of the authentic
honey. PLS-DA was shown as an effective classification method to discriminate South
African from intentionally adulterated as well as imported honey [51]. Overall classification accuracies of between 93.3 and 99.9% were obtained. The handheld device
evaluated in this study performed as accurately as the desktop instrument.
15.9 Tea
Growth in the functional food and bioactive ingredients markets encouraged the
application of NIR spectroscopy within this field. McGoverin et al. [52] provided
an extensive review on the quantification of bioactive compounds within food
commodities such as tea.
Tea is of great interest due to its beneficial health properties. It is made from
the processed leaves of Camellia sinensis and one of the most popular beverages
consumed worldwide. Osborne and Fearn [53] reported one of the first discriminant
studies on tea, distinguishing between black teas of differing sensory profiles. Grant
et al. [54] showed a reliable classification of six teas differing in origins and taste.
The effect of the grinding method when preparing and analysing powdered samples
by NIR spectroscopy should always receive suitable attention [53]. Using SIMCA
as a classification modelling technique, it was possible to identify four different tea
varieties [55]. Manley et al. [56] quantified the major phenolic compounds, soluble
solid content and total antioxidant activity of green rooibos (Aspalathus linearis), an
indigenous South African herbal tea.
353
15.8 Honey
Initial NIR spectroscopy studies on honey mainly comprised the determination of
its chemical composition [48]. Honey is a completely natural, high-value product
comprising simple carbohydrates with a distinct sucrose–glucose–fructose profile
and water. Cane invert sugar preparations are often prepared to mimic this profile
and added to pure honey. Addition of such preparations is usually difficult to detect.
Differences in floral species, maturity, environment, processing and storage techniques contribute to the natural variability of honey and thus the complexity of
detecting honey adulteration.
The use of NIR spectroscopy and PLS-DA to detect adulterated honey has been
demonstrated [49]. The addition of fructose and glucose could be detected with a
high degree of success (99%). Similarly, the pure honey could be accurately identified
(96%). The importance of temperature control during NIR analysis was, however,
stressed. When SIMCA was evaluated as a discrimination technique [50], the adulterated honey could be 100% correctly identified compared to only 90% of the authentic
honey. PLS-DA was shown as an effective classification method to discriminate South
African from intentionally adulterated as well as imported honey [51]. Overall classification accuracies of between 93.3 and 99.9% were obtained. The handheld device
evaluated in this study performed as accurately as the desktop instrument.
15.9 Tea
Growth in the functional food and bioactive ingredients markets encouraged the
application of NIR spectroscopy within this field. McGoverin et al. [52] provided
an extensive review on the quantification of bioactive compounds within food
commodities such as tea.
Tea is of great interest due to its beneficial health properties. It is made from
the processed leaves of Camellia sinensis and one of the most popular beverages
consumed worldwide. Osborne and Fearn [53] reported one of the first discriminant
studies on tea, distinguishing between black teas of differing sensory profiles. Grant
et al. [54] showed a reliable classification of six teas differing in origins and taste.
The effect of the grinding method when preparing and analysing powdered samples
by NIR spectroscopy should always receive suitable attention [53]. Using SIMCA
as a classification modelling technique, it was possible to identify four different tea
varieties [55]. Manley et al. [56] quantified the major phenolic compounds, soluble
solid content and total antioxidant activity of green rooibos (Aspalathus linearis), an
indigenous South African herbal tea.