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The thermal process of green amaranth leads to the partial or complete degradation of chlorophyll pigments and loss of green colour due to the formation of chlorophyll derivatives. This study aimed to evaluate a stabilisation process utilising metal ions to obtain a stable green colour of metal-chlorophyll derivative complexes. In this study, the effects of CuSO4 (0–240 ppm), ZnCl2 (0–1800 ppm) ions, pH (4–9), and temperature (60–100 °C) on green amaranth purees with a constant time of 15 min were investigated. In tapered leaf amaranths, the sample depicted higher contents of chlorophyll a (0.33 mg/g), chlorophyll b (0.34 mg/g), and total chlorophyll (0.68 mg/g) than round leaf amaranths (chlorophyll a = 0.28 mg/g, chlorophyll b = 0.29 mg/g, and total chlorophyll = 0.58 mg/g). A higher chlorophyll derivative content (0.62 mg/g), DPPH scavenging activity (93 mM TE/g), and FRAP value (54 mM TE/g) of Cu-amaranth purees were successfully achieved using 210 ppm of CuSO4 after heating at pH 6 and 80 °C. Zn-amaranth purees were produced using 1500 ppm of ZnCl2 at pH 8 and 90 °C for 15 min with chlorophyll derivative content of 0.39 mg/g, DPPH scavenging activity of 79 mM TE/g, and FRAP value of 57 mM TE/g. In HPLC chromatograms, two major peaks were identified as chlorophylls a and b in fresh amaranths. Nevertheless, these two peaks disappeared in Cu- and Zn-amaranth purees, presumably due to the formation of metallo-chlorophyll derivatives. [ABSTRACT FROM AUTHOR]

Current work evaluated the effects of 12-month storage, at chilled (4ºC) and ambient (25ºC) temperatures, on the physical properties, resistant starch (RS) content and antioxidant profile of purple sweet potato (PSP) powder. This study revealed two findings: (i) The antioxidant content of food powders was not always reflective of its antioxidant capacity and (ii) Chilled storage could not prevent the loss of RS and antioxidant activity upon 12-month storage. It is suggested that measurements of antioxidant content and antioxidant activity should be performed concurrently on the same sample. [ABSTRACT FROM AUTHOR]

Pomegranate peel is a rich source of phenolic compounds (such as punicalagin and hydroxybenzoic acids). However, the content of such bioactive compounds in the peel extract can be affected by extraction type and condition. It was hypothesized that the optimization of a pulsed ultrasound-assisted extraction (PUAE) technique could result in the pomegranate peel extract with higher yield and antioxidant activity. The main goal was to optimize PUAE condition resulting in the highest yield and antioxidant activity as well as the highest contents of punicalagin and hydroxybenzoic acids. The operation at the intensity level of 105 W/cm 2 and duty cycle of 50% for a short time (10 min) had a high efficiency for extraction of phenolics from pomegranate peel. The application of such short extraction can save the energy and cost of the production. Punicalagin and ellagic acid were the most predominant phenolic compounds quantified in the pomegranate peel extract (PPE) from Malas variety. PPE contained a minor content of gallic acid. [ABSTRACT FROM AUTHOR]