GB2196144A

GB2196144A - Liquid comparator -

Info

Publication number: GB2196144A
Application number: GB08624279A
Authority: GB
Inventors: Christopher Anthony Counsell
Original assignee: TINTOMETER Ltd
Current assignee: TINTOMETER Ltd
Priority date: 1986-10-09
Filing date: 1986-10-09
Publication date: 1988-04-20
Also published as: GB8624279D0

Abstract

An optical liquid comparator comprising a combined liquid sampling and viewing unit (10), a translucent optical colour reference or standard element (17) being mounted in a reference window (18) in a viewing frame for colour comparison with an adjacent sample liquid optical viewing window (20) of a sampling chamber or cup (12) for receiving a liquid sample. It is particularly used to assess the condition of frying oil. <IMAGE>

Description

SPECIFICATION Liquid comparator This invention relates to a liquid comparator and is particularly, but not exclusively, concerned with an optical comparator for a culinary liquid, in particular a frying oil-specifi- cally for testing or assessing the physical and/or chemical condition of frying oil by reference to its optical characteristics, especially its colour.

The condition of a frying oil is critical in culinary use at elevated temperatures in order to ensure healthy, efficient and untainted frying.

Known methods of assessing the condition of frying oil involve comparison of the colour of a sample of the body of oil with a printedpaper standard, in order to establish the socalled "discard-point", at which the oil condition is unacceptable for further culinary use.

Beyond this point, the taste and efficacy of cooking food with this oil are adversely affected-and, more importantly, the oil may become a health hazard, due to the steady accumulation of saturated fats in the oil.

According to one aspect of the present invention there is provided a liquid comparator comprising a combined liquid sampling and viewing unit, an optical colour reference or standard, for example,, a tinted glass or a printed plastics sheet or foil, being mounted in a reference window in a viewing frame for colour comparison and an adjacent sampling chamber with an associated optical viewing window.

According to another aspect of the invention, there is provided a method of testing the condition of a liquid by reference to its optical characteristics using the comparator according to the immediately preceding paragraph, the method comprising the steps of taking a sample of the liquid to be assessed, using the sampling unit as a scoop or ladle, viewing said sample against a background light source and comparing the perceived sample colour with that of the reference window.

Preferably, the comparator is heat-resistant, in order to enable liquid sampling and analysing at elevated temperatures, for example in excess of 130 degrees Centigrade.

Conveniently, the sampling element comprises a form of scoop or ladle, with a bucket portion mounted upon a suspension arm incorporating a handle, fixed or pivotally secured thereto, whereby the bucket may be handled remotely and immersed to the arm depth in a liquid to be sampled and analysed.

Desirably, the sampling element incorporates a reference window, with a colour filter of a reference or standard colour, for comparison with the colour of the original sample taken.

Conveniently, the sampling element also incorporates a sample viewing window accessible to any liquid contained therein; the sample viewing window being disposable alongside the reference window.

In a particular arrangement, the reference window and viewing window are disposed in a common frame supporting the sampling unit.

The reference window is conveniently a printed foil strip, which may also bear adjacent descriptions or operating instructions, and which is applied to overlay the frame.

The sample window desirably includes a window disposed to ensure contact with the liquid sample surface when the sampling element is filled with liquid.

There now follows a description of a particular embodiment of a frying oil comparator according to the invention, by way of example only, with reference to the accompanying diagrammatic drawings, in which: Figure 1 shows a plan view of one embodiment of a frying oil comparator according to the invention, adapted for a single colour comparison at a time; Figure 2 shows a side elevation of the assembled comparator shown in Fig. 1; Figure 3 shows a plan view of another embodiment of a frying oil comparator according to the invention adapted for a dual colour comparison at a time; Figure 4 shows a side elevation of the comparator shown in Fig. 3; Figures 5, 6 and 7 show the sequence of operation for using the comparator shown in Figs. 1 and 3.

Referring to the drawings, a frying oil comparator 10 for testing the condition of a liquid sample of frying oil by reference to its optical characteristics, and in particular its colour, comprises an open-framed handle portion 15 supporting a sampling cup 12 mounted at its opposite end with an intermediate colour reference standard.

Thus the comparator 10 essentially takes the form of a scoop or ladle for immersion in a body of a liquid, specifically a frying oil to be sampled. As shown in Figs. 5, 6 and 7, by virtue of the longitudinal extent of the handle 15 from the sample cup 12, samples to some depth may be taken remotely, yet the users hand 50 is kept clear of the oil 40.

The comparator 10 incorporates an (upper) reference window aperture 18 and a (lower) sample viewing window aperture 20 (with an element). Surmounting the reference window 18 is a filter element 1 7 located in a recess 16 in the underside of the body 10 as shown in Fig. 2.

The filter 17 incorporates a colour reference element or standard overlying the reference window, together with descriptive information and/or user operating instructions.

The window aperture 20 contacts any liquid, e.g. frying oil sample in the sampling cup 12.

The entire comparator 10 is fabricated of heat-resistant material, conveniently by moulding from synthetic plastics material, in order to allow sampling of oil at elevated temperatures-for example in excess of 130 degrees Centigrade.

Figs. 3 and 4 show what is essentially a twin-colour test version of the single-colour test comparator of Figs. 1 and 2. Thus, a comparator body 30 incorporates a handle frame 25 and a pair of spaced reference windows 28 and 29 aligned respectively with a pair of spaced viewing windows 31 and 32.

A single foil sheet 27, mounted in a recess 26 on the underside of the body 30 as shown in Fig. 4, incorporates two different colour references or standards respectively overlying the reference windows 28 and 29.

The principle upon which the comparator is based is the monitoring and assessment of the colour and the change in colour, reflecting chemical and/or physical changes which frying oil undergoes as it is repeatedly used for cooking at elevated temperatures, over successive heating and cooking cycles. Once the oil has undergone changes to a certain degree, it is no longer regarded as satisfactory for further use and must be disposed of.

Colour assessment of the oil must be by comparison with a strictly prepared predetermined colour standard or reference, for which purpose the sample and the reference must be ideally held adjacent one another and viewed in similar ambient light conditions and/or against a common background reference light source-the latter being important when the colour of a translucent sample is being determined by comparison with a translucent reference sample.

As depicted in Figs. 5, 6 and 7, the sequence of operations is generally as follows; The comparator 10 is grasped by the handle 15 in the hand 50 and held generally upright with the sampling unit 12 disposed at its lower end. The latter is immersed in the body of frying oil 40 to be sampled, allowing oil to enter the sampling cup 12 through its open upper mouth 13 and is then withdrawn therefrom, leaving the sampling cup 12 full of a sample of oil and with the viewing window 20 engaging the liquid oil sample surface in the sampling cup 12.

The oil sample in the sample cup 12 is then viewed against a common ambient and/or artificial background light source through the viewing window 20 alongside the reference window 18. Departure from the "acceptance" standard, or correspondence with a non-acceptance standard, indicates the oil has deteriorated to an unacceptable standard.

Claims

1. An optical liquid comparator comprising a combined liquid sampling and viewing unit, a translucent optical colour reference or standard element being mounted in a reference window in a viewing frame for colour comparison with an adjacent sample liquid optical viewing window of a sampling chamber or cup for receiving a liquid sample.

2. A comparator, as claimed in Claim 1, wherein the viewing frame is incorporated in a handle for offering the viewing window and reference window to a common background light source and supporting the sample chamber for immersion in a liquid to be sampled.

3. A comparator, as claimed in either of the preceding Claims, incorporating a plurality of colour reference windows for multiple colour comparisons.

4. A comparator, as claimed in any of the preceding Claims, wherein the viewing and reference windows are of substantially the same shape and size.

5. A comparator, substantially as hereinbefore described, with reference to, and as shown in, the accompanying drawings.

6. A method of testing or analysing the (physio-chemical) condition of a liquid by reference to its optical characteristics, in particular its colour translucence, using a comparator as clamed in any of the preceding Claims, the method comprising the steps of taking a sample of the liquid to be tested or analysed by immersing the sample chamber (or cup), holding the comparator by the handle, and withdrawing the sample chamber with the liquid sample surface generally level, offering the sample liquid up to a background light source, and viewing the sample through the viewing window of the sample chamber, alongside the reference window, in order to effect a colour comparison therewith.