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D. P. Hackett

Bio: D. P. Hackett is an academic researcher. The author has an hindex of 1, co-authored 1 publications receiving 1972 citations.


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Book ChapterDOI
TL;DR: In this article, the spectral characteristics and absorption coefficients of chlorophylls, pheophytins, and carotenoids were analyzed using a two-beam spectrophotometer.
Abstract: Publisher Summary This chapter presents detailed information on chlorophylls and carotenoids to give practical directions toward their quantitative isolation and determination in extracts from leaves, chloroplasts, thylakoid particles, and pigment proteins. The chapter focuses on the spectral characteristics and absorption coefficients of chlorophylls, pheophytins, and carotenoids, which are the basis for establishing equations to quantitatively determine them. Therefore, the specific absorption coefficients of the pigments are re-evaluated. This is achieved by using a two-beam spectrophotometer of the new generation, which allows programmed automatic recording and printing out of the proper wavelengths and absorbancy values. Several procedures have been developed for the separation of the photosynthetic pigments, including column (CC), paper (PC), and thin-layer chromatography (TLC) and high-pressure liquid chromatography (HPLC). All chloroplast carotenoids exhibit a typical absorption spectrum that is characterized by three absorption maxima (violaxanthin, neoxanthin) or two maxima with one shoulder (lutein and β-carotene) in the blue spectral region.

10,367 citations

Journal ArticleDOI
TL;DR: In this paper, the extinction coefficients for chlorophylls a and b in diethylether (Smith, J.H. and Benitez, A.V., eds.), used in this paper as primary standards, were verified by magnesium determination using atomic absorbance spectrophotometry.

5,326 citations

Journal ArticleDOI
TL;DR: In this paper, the authors highlight the potential of selected by-products as a source of functional compounds and highlight the benefits of using these byproducts as functional compounds in the context of food processing.
Abstract: There is a rapidly growing body of literature covering the role of plant secondary metabolites in food and their potential effects on human health. Furthermore, consumers are increasingly aware of diet related health problems, therefore demanding natural ingredients which are expected to be safe and health-promoting. By-products of plant food processing represent a major disposal problem for the industry concerned, but they are also promising sources of compounds which may be used because of their favourable technological or nutritional properties. The purpose of this review is to highlight the potential of selected by-products as a source of functional compounds.

1,196 citations

Journal ArticleDOI
TL;DR: How the ratios are increasingly and alarmingly low as the proportion of chlorophyll a increases is described, which is always low.
Abstract: Over the last half century, the most frequently used assay for chlorophylls in higher plants and green algae, the Arnon assay [Arnon DI (1949) Plant Physiol 24: 1–15], employed simultaneous equations for determining the concentrations of chlorophylls a and b in aqueous 80% acetone extracts of chlorophyllous plant and algal materials. These equations, however, were developed using extinction coefficients for chlorophylls a and b derived from early inaccurate spectrophotometric data. Thus, Arnon’s equations give inaccurate chlorophyll a and b determinations and, therefore, inaccurate chlorophyll a/b ratios, which are always low. This paper describes how the ratios are increasingly and alarmingly low as the proportion of chlorophyll a increases. Accurate extinction coefficients for chlorophylls a and b, and the more reliable simultaneous equations derived from them, have been published subsequently by many research groups; these new post-Arnon equations, however, have been ignored by many researchers. This Minireview records the history of the development of accurate simultaneous equations and some difficulties and anomalies arising from the retention of Arnon’s seriously flawed equations.

1,176 citations