Function of anti-caking agents – a case study

UNDERSTANDING YOUR FOOD<br /> the ultimate educational resource<br /> TEACHER NOTES<br /> <br /> teachers’ notes AC2.1<br /> AC2. The function of anti-caking agents - a case study<br /> The effect of Neosyl GP (silicon dioxide, E551) on the ability of<br /> Sainsbury’s cocoa to flow is investigated.<br /> The case study, on pupils sheet AC2, gives the procedures and results for<br /> an example investigation. You may prefer to replace the actual<br /> experiment AC1 with a discussion of AC2.<br /> Neosyl GP (GP = general purpose) is an anti-caking agent. It is capable of<br /> improving the flow of many powders. Sainsbury’s cocoa does not contain a<br /> free- flow agent. Other brands could be used as long as they too<br /> contained only cocoa.<br /> Aim of the first part of the investigation: to determine the orifice size<br /> through which cocoa without Neosyl GP will not readily flow.<br /> Aim of the remaining investigations: to determine the effect on the flow<br /> of cocoa with Neosyl GP added.<br /> KS3 and 4<br /> science<br /> Timing - various<br /> Two pupil activity sheets AC2<br /> accompany this case study.<br /> <br /> THE FUNCTION OF ANTI-CAKING AGENTS - A CASE STUDYpupil activity AC2<br /> Investigation into the effect of Neosyl GP (silicon dioxide, E551) on the ability of<br /> Sainsbury’s cocoa to flow<br /> Method 1<br /> 1. Different sized funnels were prepared by removing ‘stems’.<br /> 2.100 g of cocoa was placed in the funnels.<br /> 3.The sides of the funnels were tapped to allow cocoa to flow through.<br /> 4.The number of taps required to remove all the powder was counted.<br /> 5.Each test was done 6 times and an average calculated.<br /> Results: Cocoa without Neosyl GP<br /> Orifice size Number of taps<br /> mm 1 2 3 4 5 6 Average<br /> 50 4 4 2 2 2 2 3<br /> 40 2 1 1 7 3 3 3<br /> 30 44202021 2123 25<br /> On the basis of these results, the funnel with the 30 mm orifice was chosen for<br /> subsequent experiments as cocoa would not readily flow through this size.<br /> Method 2<br /> 1.100 g of cocoa powder was mixed with varying amounts of Neosyl GP so that the<br /> Neosyl GP was present as 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 % by weight of the final<br /> mixture.<br /> 2.The mixing took place in a plastic bag. The two substances were placed in the<br /> bag and shaken vigorously.<br /> 3.Each mixture was placed in the funnel, as described before, and the number of<br /> taps needed to get all the powder through the funnel were counted. Each<br /> experiment was repeated 6 times.<br /> 4.One of the mixtures, the 0.3 %, was left for ~48 hours before carrying out the test.<br /> 5.A 0.6 % mixture was left for ~24 hours before being tested.<br /> Results: Cocoa with Neosyl GP<br /> Neosyl GP Number of taps<br /> % 1 2 3 4 5 6 Average<br /> 0.1 23252519 1920 22<br /> 0.2 27232016 1719 20<br /> 0.3* 7 7 6 6 7 5 6<br /> 0.4 6 7 5 3 2 2 4<br /> 0.5 5 2 2 4 3 4 3<br /> 0.6 7 5 3 2 7 6 5<br /> 0.6** 3 2 2 2 2 4 3<br /> * After an interval of ~48 hours<br /> ** After an interval of ~24 hours<br /> <br /> pupil activity AC2THE FUNCTION OF ANTI-CAKING AGENTS - A CASE STUDY<br /> Discussion: There appears to be a sudden improvement in flowability between the 0.2<br /> and 0.3 % levels. It is not clear whether this is due to the increase in the level of the<br /> flow aid or to the fact that the mixture was allowed to stand for some time. Leaving<br /> the 0.6 % to stand seems to have improved its flowability. The experiment wasrepeated<br /> starting with the 0.4 % mixture.<br /> Results: Cocoa with Neosyl GP, repeats<br /> Neosyl GP Number of taps<br /> % 1 2 3 4 5 6 Average<br /> 0 272739262624 28<br /> 0.4 16201412 1510 14.5<br /> 0.5 1116 9 1212 8 11<br /> 0.6 11 9 7 7 7 6 8<br /> 0.7 5 4 3 4 8 4 5<br /> 0.7* 1 2 2 1 2 1 1.5<br /> * After ~48 hours<br /> Discussion: These results show some variance with the previous results, some of which<br /> were supposed to be identical repeats. The results indicate that considerably more<br /> than the 0.3% Neosyl GP is needed to achieve good flowability. Leaving the mixtureto<br /> stand for a while is again observed to result in improved flowability.<br /> The experiment was repeated again with larger amounts of Neosyl GP.<br /> Results: Cocoa with more Neosyl GP.<br /> Neosyl GP Number of taps<br /> % 1 2 3 4 5 6 Average<br /> 0 351319133122 22<br /> 0.7 7 9 9 4 9 3 7<br /> 1.0 3 4 2 4 3 2 3<br /> Discussion: It appears from the data that the maximum allowed dose of 1.0% Neosyl<br /> GP will almost make the cocoa entirely free flowing and that leaving the mixture to<br /> stand improves the flow.<br /> The improvement in flow when left to stand may be due to the fact that the Neosyl GP<br /> is capable of absorbing fat. Cocoa has a fat content of ~20 %. The absorption of<br /> fat by the Neosyl GP may thus allow the particles of cocoa to flow more freely.<br /> The action of an anti-caking agent can be demonstrated using ball bearings or<br /> something similar. If particles of the same size are within a container, they reach a<br /> point where they ‘lock’ together and become stationary. The addition of other<br /> spheres ofdifferent sizeshas the effect of ‘unlocking’ the spheres so that they move<br /> again. Cocoa consists of small particles of similar size. The Neosyl GP consists of<br /> particles of a different size to the cocoa. Mixing of the two increases the mobility of<br /> the cocoa particles.