METHOD FOR SMOKING LIQUIDS AND DEVICE THEREFOR

Abstract

A method of treating a solution (e.g. comprising water and optional other components) to make smoked water for flavouring food, comprises: (i) providing a source of smoke and filtering the smoke to reduce its PAH content, (ii) providing a smoking vessel (e.g. pan) containing the solution, and (iii) introducing bubbles of filtered smoke into the solution while agitating the solution so as to break up the introduced smoke into a plurality of smaller bubbles of average diameter 2 mm or less.

Claims

1-32. (canceled)

33. A method of treating a solution, comprising: (i) providing a source of smoke, (ii) providing a smoking vessel containing the solution, and (iii) introducing bubbles of smoke into the solution while agitating the solution so as to break up the introduced smoke into a plurality of smaller bubbles.

34. The method of claim 33 comprising filtering the smoke to reduce its PAH content.

35. The method of claim 33, comprising breaking the smoke into bubbles of average diameter 2 mm or less.

36. The method of claim 33, comprising introducing the smoke into the solution at a mixing head of a mixer while agitating the solution with the mixer so as to break up the introduced smoke into bubbles.

37. The method of claim 33, comprising venting the smoking vessel to the atmosphere.

38. The method of claim 33, wherein there is no recirculation of off-gas back through the solution.

39. The method of claim 33, comprising monitoring the method and adjusting the agitation to reduce to a minimum the smoke bubbles that escape from the solution being smoked.

40. The method of claim 33, comprising cooling the solution so as to maintain it at a temperature of 30 C. or below.

41. The method of claim 40, comprising cooling the solution so as to maintain it at a temperature of 20 C. or below.

42. A method of treating a solution, comprising: (i) providing a source of smoke that has optionally been filtered to reduce its PAH content, (ii) providing a smoking vessel containing the solution, (iii) introducing the smoke into the solution at a mixing head of a mixer and no more than 3 cm from a blade of the mixer, while agitating the solution with the mixer blade so as to break up the introduced smoke into a plurality of bubbles of average diameter 2 mm or less, (iv) venting the smoking vessel to the atmosphere, and (v) cooling the solution so as to maintain it at a temperature of 30 C. or below.

43. A method of treating a solution, comprising: (i) providing a source of smoke, (ii) providing a smoking vessel containing the solution, and (iii) introducing bubbles of smoke into the solution while agitating the solution so as to break up the introduced smoke into a plurality of smaller bubbles, wherein there is no recirculation of off-gas back through the solution.

44. The method of claim 43 comprising filtering the smoke to reduce its PAH content.

45. The method of claim 43 comprising breaking the smoke into bubbles of average diameter 2 mm or less.

46. Apparatus for treating a solution, comprising: a smoke chamber having an air input and a smoke output and in which fuel can be combusted to generate smoke; a smoking vessel capable of holding the solution to be treated; a mixer for mixing contents of the smoking vessel; a conduit from the output of the smoke chamber to the smoking vessel with an exit for introducing the smoke into the solution, below the surface of the solution; wherein the mixer is adapted to agitate the solution so as to break up the introduced smoke into bubbles; and wherein there is no conduit permitting recirculation of off-gas back through the solution.

47. The apparatus of claim 46, comprising a filter for filtering the smoke to reduce its PAH content before it is introduced into the solution.

48. The apparatus of claim 46, comprising fuel mixed with filter material.

49. The apparatus of claim 46, wherein the mixer is adapted to break the smoke into bubbles of average diameter 2 mm or less.

50. The apparatus of claim 46, comprising a chimney to vent the smoking vessel to the atmosphere.

51. The apparatus of claim 46 comprising a cooler to cool the solution during smoking.

52. The apparatus of claim 46, wherein the mixer comprises a mixing head having a rotor blade.

Description

[0099] The invention is now described in specific examples with reference to the accompanying drawings in which:

[0100] FIG. 1 shows a schematic diagram of a laboratory-scale smoker of the invention;

[0101] FIG. 2 shows a schematic diagram of an industrial-scale smoker of the invention;

[0102] FIG. 3 shows a star diagram of the results of testing mouthfeel and after effects of chicken brined in water smoked according to the invention: A smoked with no filtration, B-D increased levels of filtration from B to D;

[0103] FIG. 4 shows a star diagram of the results of testing taste of chicken brined in water smoked according to the invention: A smoked with no filtration, B-D increased levels of filtration from B to D;

[0104] FIG. 5 shows a star diagram of the results of testing flavour of chicken brined in water smoked according to the invention: A smoked with no filtration, B-D increased levels of filtration from B to D;

[0105] FIG. 6 shows a plot of smoking time (hours) vs pH of smoked water, comparing the smoking method of the invention with the smoking method described in US 2012/0207898; and

[0106] FIG. 7 shows a plot of smoking time (hours) vs luminosity of smoked water, comparing the smoking method of the invention with the smoking method described in US 2012/0207898.

EXAMPLES

Example 1Laboratory Scale Water Smoker

[0107] We developed a water smoker 10 for preparation of smoked water, calibrated it, made smoked water, brined chicken in the smoked water and tested the chicken.

[0108] A compressor 12 was linked by pipe 14 to airtight smoke chamber (approx. 100 litres) 16, containing combustible material 20 (wood dust optionally with added filter material). The chamber smoke output was in turn linked to the stator portion of mixing head 28 of a YTRON Y-ByPass mixer 24 via silicone rubber linking tube 22 and bypass pipe 26. The mixer is approximately 0.6 m tall with a power of 4.5 KW. The mixing head 28 is submerged during operation in water in a circular cross-section water pan (approx. 15 litres) 30.

[0109] Calibration Runwe smoked water using the apparatus for periods varying from 1 hour to 24 hours and compared the intensity of the product with conventionally obtained smoked water made in-house by the inventor using static water trays. Air was flowed into the smoke chamber 16 at approximately 127 litres per minute. Oak dust was placed in the bottom of the chamber (replenished as required) and electrical heat source 18 was switched on to ignite the dust, producing smoke. The air flow directed smoke to the mixing head via the linking tube and the bypass pipe. The mixer was turned on and also exerted a low level of suction, thus drawing smoke down the bypass pipe and into the water in the pan. The bypass pipe exit was of diameter approx. 25 mm and was located approximately 6 mm above the spinning impellers (set to approx. 60 Hz) of the mixer inside the mixing head, delivering the chamber output smoke right into the centre of the mixing; as the impellers span the smoke was intimately homogenised into tiny bubbles at the centre of the mixing head, with frothing seen at and around the head and at the water surface. Tiny bubbles were also seen dispersed throughout the water, swirling in the mixed water, having long residence times before rising to the surface. The few bubbles of smoke passing through the solution escaped into the atmosphere directly.

[0110] The smoked water made by smoking for 6 hours according to the invention was found comparable to water smoked in trays in a smoker for 4 days.

[0111] Brine for brining chicken was then prepared as follows. Air was flowed into the smoke chamber 16 as before. Initially, 2 kg of oak dust was placed in the bottom of the chamber and electrical heat source 18 was switched on to ignite the dust, producing smoke. This amount of dust was by then known to burn for approximately 4 hours so after a little less than 4 hours a further 1 Kg of dust was added to give a total burn time of approximately 6-7 hours.

[0112] The smoking and mixing was continued for approximately 6 hours, then the compressor and mixer switched off and the remaining dust left to extinguish by cutting off the air supply.

[0113] Run AThe smoked water was removed and then used as brine for chicken pieces, which were left to soak in the smoked water for 24 hours. This run was referred to as unfiltered.

[0114] Runs B-DThe process was then repeated, with alternative fuel sources (retaining the same amount of oak but supplemented with clinoptilolite filter as described in WO 2015/007742), these runs being referred to as with increasing levels of filtration: [0115] B oak dust plus clinoptilolite at weight ratio 4:1 (PST 25) [0116] C oak dust plus clinoptilolite at weight ratio 2:1 (PST 50) [0117] D oak dust plus clinoptilolite at weight ratio 1:1 (PST 100)

[0118] The chicken pieces from the brines of runs A-D were then tested as now described, with reference to FIGS. 3, 4 and 5.

[0119] FIG. 3 shows a star diagram of the results of a sensory panel tasting of the chicken for mouthfeel and after effects. The more filtration that was introduced the more balanced the flavour became, with less acrid ash tray qualities.

[0120] FIG. 4 shows a star diagram of the results of a sensory panel tasting of the chicken for overall taste. These results recorded a more desirable flavour profile for runs B-D, D scoring highest, complementing the chicken by improving the umami, salt and sweet flavour character.

[0121] FIG. 5 shows a star diagram of the results of a sensory panel tasting of the chicken for flavour. Interestingly, the panel reported an improved balance of flavours, which allowed the chicken flavour to come through whilst reducing the flavours associated with acridity, smokiness, ash tray character and smoked fish.

Example 2Industrial Scale Water Smoker

[0122] An industrial scale water smoker 40 was designed for larger scale water smoking.

[0123] Combustible materials (e.g. wood, botanicals) are fed from container 42 into industrial smoke generator 44. The smoke passes through linking pipe 46 to bypass pipe 48, which delivers the smoke directly into the mixing head 58 of large scale homogeniser 50. We designed this smoker to work with a known YTRON Y-ByPass mixer of power 11.5 KW. The mixing head 58 is suspended in a water vessel 54 containing up to 5,000 litres of liquid. The smoked liquid is collected from the vessel 54 by tap 56. Bubbles of smoke passing through the solution are vented directly to the atmosphere via a short chimney (not shown). The chimney allows for inclusion off-gas scrubbing units if desired, e.g. according to local emissions regulations.

Example 3pH Testing of Smoked Water

[0124] We smoked water as per the prior art method referred to the calibration run of Example 1 and compared its pH with water smoked according to the invention using no filtration and then filtration levels PST25 and PST50. The filtered, smoked water of the invention had higher pH, i.e. was less acidic, than known smoked water:

TABLE-US-00001 pH Smoked Water (prior art) Standard tray-smoked water 3.9 Smoked Water (invention) No filtration 3.9 PST25 4.5 PST50 5.7

Example 4Smoked Oil

[0125] We smoked sunflower oil following the method of Example 1 of the invention, modified as follows: 8 litres of oil, 3 kg of wood, Y-tron mixer set at 22 Hz after trials at different settings, air flow as before. This combination gave little throughput of smoke to the vent. With this set up oil was smoked unfiltered and filtered with PST25.

[0126] Oil samples were tested and found to make a pleasant smoky flavour.

Example 5Comparative Study

[0127] We compared the efficiency of the smoking method of the invention with smoking methods known in the prior art. Specifically, the prior art smoking method involved passively introducing small bubbles of smoke into the water, as in US 2012/0207898.

[0128] As in Example 1, a compressor 12 was linked by pipe 14 to airtight smoke chamber (approx. 100 litres) 16, containing combustible material 20 (wood dust). The chamber smoke output was in turn linked to the stator portion of mixing head 28 of a YTRON Y-ByPass mixer 24 via silicone rubber linking tube 22 and bypass pipe 26. The mixer is approximately 0.6 m tall with a power of 4.5 KW. The mixing head 28 is submerged during operation in water in a circular cross-section water pan (approx. 15 litres) 30.

[0129] Air flowed into the smoke chamber 16 at approximately 127 litres per minute. Oak dust was placed in the bottom of the chamber (replenished as required) and electrical heat source 18 was switched on to ignite the dust, producing smoke. The air flow directed smoke to the mixing head via the linking tube and the bypass pipe. The mixer was turned on and also exerted a low but notable level of suction, thus drawing smoke down the bypass pipe and into the water in the pan. The bypass pipe exit was of diameter approx. 25 mm and was located approximately 6 mm above the spinning impellers (set to approx. 60 Hz) of the mixer inside the mixing head, delivering the chamber output smoke right into the centre of the mixing; as the impellers span the smoke was intimately homogenised into tiny bubbles at the centre of the mixing head, with frothing seen at and around the head and to a lesser extent at the water surface. Tiny bubbles were also seen dispersed throughout the water, swirling in the mixed water, having long residence times before rising to the surface. The few bubbles of smoke passing through the solution were vented into the atmosphere directly.

[0130] In the comparative run, water was smoked in the same way (fuel, amount of fuel, air flow, water pan, smoke chamber etc.) but instead with the chamber smoke output linked to a perforated nozzle submerged in the water pan. The perforated nozzle was configured to closely simulate the effect of the mesh used in US 2012/0207898, thereby breaking up the smoke into fine bubbles as the smoke entered the water. It was felt not necessary to replicate the closed nature of the system of US 2012/0207898, as this feature was determined to have no or insignificant bearing on the rate at which smoke is introduced into the water; rather, the closed system acts to reduce fuel consumption by re-circulating generated smoke multiple times. It is arguable, even, that the replication carried out in this comparative study is more effective than the setup in US 2012/0207898 at introducing smoke into water quickly; this is because newly generated smoke, containing a higher saturation of smoke components than recirculated smoke, is continually being introduced to the water.

[0131] During smoking, all parameters were controlled and matched between the respective methods. Continuous pH measurement was performed using an Edge pH meter (Hanna Instruments). Colour measurements were taken under standard illumination and analysed using the Pantone application. Sensory analysis was also performed.

[0132] Statistical analysis was carried out using ANOVA in combination with a post-hoc Tukey test. The results are shown in FIGS. 6 and 7. Results are presented as mean+/standard deviation and are considered significant when p<0.05.

[0133] As illustrated in FIG. 6, a faster decrease in the pH of smoked water is observed when using the smoking method of the invention (dashed line), opposed to the passive bubbling method of the prior art (solid line).

[0134] Commercially, smoked water is commonly sold at a pH of around 4.0. Using the smoking method of the invention, this pH was reached after around 2 hours of smoking, whereas the prior art method as per the reproduction herein required 6 hours of smoking to achieve a similar decrease in the pH of the water. Furthermore, it was observed that pH starts to plateau at around pH 4 using the reproduced prior art smoking method, whereas using the smoking method of the invention the pH started to plateau at around pH 3. This suggests that a more concentrated smoked water is achievable using the smoking method of the invention.

[0135] Luminosity of the smoked water is outlined in FIG. 7. It is observed that the luminosity of the water smoked using the smoking method of the invention (dashed line) decreases more quickly than when the water is smoked using the reproduced prior art smoking method (solid line). As a decrease in luminosity represents a higher degree of smoke integration into the water, these data confirm that the smoking method of the invention was a more powerful and more time-efficient method. Again, it is shown that a similar luminosity (67) is achieved after 2 hours using the smoking method of the invention, versus 6 hours using the smoking method of the reproduced prior art. Additionally, it is observed that a far lower luminosity (46) is achievable when water is smoked for 6 hours using the smoking method of the invention.

[0136] Furthermore, in respect of both pH and colour (luminosity) measurements, the results obtained for each hourly time point demonstrate a higher degree of reliability between individual experiments (n=3) for the smoking method of the invention. This can be seen in FIGS. 6 and 7, respectively, which both clearly show reduced standard deviation from the mean for the smoking method of the invention (dashed line) versus the prior art smoking method (solid line), indicating the invention provides a consistent and reproducible process.

[0137] The pH and colour measurements described above correlate strongly with sensory data obtained and illustrated in Tables 1 and 2:

TABLE-US-00002 TABLE 1 Sensory analysis of samples smoked with the smoking method of the invention. Sample Colour Aroma Taste 1 hr Pale yellow, Mild smoke. Mild smoky taste. Slightly straw-coloured oily. 2 hrs Light-yellow Mild smoke. Mildly acidic, smoky. 3 hrs Light-yellow Smoky. Acidic, smoky, slightly bitter. 4 hrs Rich yellow Very smoky. Very acidic, smoky, bitter. 5 hrs Light-amber Very smoky, Very acidic, very smoky, slightly woody. bitter. 6 hrs Amber Very smoky, Very acidic, very smoky, woody, rich. bitter, oily.

TABLE-US-00003 TABLE 2 Sensory analysis of samples smoked with the reproduced smoking method of the prior art. Sample Colour Aroma Taste 1 hr Very pale yellow Hardly detectable Mild smoke smoke 2 hrs Very pale yellow Hardly detectable Mild smoke smoke 3 hrs Pale yellow Very mild smoke Mild smoke flavour 4 hrs Pale yellow Mild smoke Smoky 5 hrs Pale yellow Mild smoke Mildly acidic, slightly smoky 6 hrs Pale yellow Mild smoke Mildly acidic, slightly smoky

[0138] The smoking method of the invention can thus be used to produce smoked water quickly and easily.

[0139] Accordingly, the invention provides methods and apparatus for smoking water, especially using filtered smoke.

PARTS LIST FOR SMOKERS

[0140] 10 water smoker [0141] 12 compressor [0142] 14 connection pipe [0143] 16 smoking chamber [0144] 18 heat source [0145] 20 combustible material [0146] 22 connection tube [0147] 24 homogeniser [0148] 26 bypass pipe [0149] 28 mixing head [0150] 30 water pan [0151] 40 industrial water smoker [0152] 42 combustible material container [0153] 44 industrial smoke generator [0154] 46 connection pipe [0155] 48 bypass pipe [0156] 50 homogeniser [0157] 58 mixing head [0158] 54 liquid vessel [0159] 56 tap