Rapid determination of chlorophylls in vegetable oils by laser‐based fluorometry

Abstract

The presence of chlorophylls in vegetable oils is considered undesirable due to their adverse effects on oxidative deterioration, bleachability and hydrogenation. The usual methods for determination of chlorophylls in vegetable oils are absorption spectrophotometry, fluorometry and liquid chromatography using fluorescence detectors. This paper outlines a fluorometric method using a laser as the excitation source. The chlorophylls in crude palm oil, rapeseed oil, soya bean oil and olive oil were determined directly by laser-based fluorometry using (a) a helium-neon laser (632.8 nm, 5 mW) as the excitation source and an optical-multichannel analyser (OMA) with an intensified diode array as the detector, and (b) a helium-neon laser and a photomultiplier tube as the detector. The method is especially suitable for the detection of chlorophylls in crude palm oil since no pre-extraction step is required. The levels of chlorophylls measured in vegetable oils using the laser technique was also compared against values obtained by conventional spectrophotometric methods. The simplicity and rapid quantification of laser based fluorometry suggest that this technique can be readily applied to the detection of a wide variety of fluorescing species in vegetable oils.

Enabling chlorophyll photo-response for in-line real-time noninvasive direct probing of the quality of palm-oil during mill process

“…3a. The chlorophyll fluorescence signal exhibits peak at the region of 665 nm which is consistent with what is reported 33 . It is evident from the spectra that the chlorophyll fluorescence signal increases proportionally with chlorophyll concentrations.…”

“…Y. A. Tan et al found that the measured chlorophyll fluorescence intensity is directly correlated to different amount of dissolved chlorophyll A added to refined palm kernel oil 33 . These alternative optical-based approaches suggest that by monitoring the chlorophyll content, it can be leveraged to estimate the FFB ripeness of palm fruit.…”

Chemical Profiling and Bioactivities of Selective Organic Compounds from Fruits of Olea ferruginea and its Comparison with Olea europaea

“…The increase in free acidity value of olive oil extracted from Malakand sample is due to the presence of free fatty acids mostly owing to oleic acid. The results of acidity of oil are comparable with the results of olive oil as reported by Tan et al [27] Peroxide value Determination of peroxide value is an important test which is related to the storage of oil and it measures the degree of rancidity of the oil. The process of oxidation happens very quickly after it has started.…”

“…High values of free acidity in the olive oil can be due to different factors such as production from an unhealthy fruit, delayed harvesting and storing before processing. [27] FFA are a source of flavours and aromas. Their breakdown products such as aldehydes, ketones, alcohols and organic acids provide characteristic flavour and aroma.…”

Insights into the bioactive compounds and physico-chemical characteristics of the extracted oils from Urtica dioica and Urtica pilulifera

“…Color is an important indication of edible oil quality, purity, and degree of deterioration and this parameter is used as an indicator to monitor each stage of the refining process to maintain a consistent quality [25]. Each oil has its own characteristics color due to the presence of chlorophyll and/or carotenoid pigments.…”