Determination of ice cream butterfat content can be quite a daunting task due to the presence of sugar in the product. Butterfat content determination procedures (e.g. Babcock method) rely on the use of a strong acid. This reagent presents a special challenge when sugar is present in the sample. Strong acids cause charring of sugar, which interferes with reading of the results. The analysis of butterfat content in ice cream, therefore, requires a modification of the current methods to circumvent the challenge.
The Babcock method has been widely adopted as a standard method for butterfat content analysis. It would be a perfect analytical procedure for this test but for its utilization of a strong acid. Sulfuric acid used in the procedure causes charring of sugar in ice cream, which interferes with the results.#Icecream contains sugar, which makes its #butterfat content determination via #Babcock method impossible. Here's how to do it right. Click To Tweet
Research has shown that sugar dissolves in 72% perchloric acid without charring. This presents a unique opportunity to modify the Babcock procedure by utilizing this reagent to avoid charring of sugar. One does not need any additional modification of the procedure or equipment, and the results will be very accurate. In addition, the centrifuge will only need to run for two minutes for complete separation.Smith et al.
Butterfat tends to darken in the presence of perchloric acid when heated to 100°C, which makes reading the levels quite difficult. To overcome this challenge, a mixture of 72% perchloric acid and 95% glacial acetic acid is used (in equal parts). This can drive up the cost of testing but it offsets the negatives by improved speed, accuracy, consistency, and simplicity. Other ingredients in the ice cream such as stabilizers, flavors, and even chocolate do not interfere with the test.
Apparatus and reagents for the determination of ice cream butterfat content
All the apparatus used in the Babcock method applies here, except for the Babcock sulfuric acid.
- Perchloric acid (72%) and 95% glacial acetic acid (1:1 mix)
- Glassware (17.6 ml pipette, 20% Babcock ice cream bottles, 50% Paley bottles, 50 ml graduated cylinder).
- Torsion balance, 9 and 18 g weights.
- Water bath at 50°C.
- Babcock centrifuge.
Procedure for determination of ice cream butterfat content
- Weigh nine grams sample of ice cream mix (or melted ice cream) into a 20% Babcock ice cream test bottle.
- Add approximately 30 ml. of the acid reagent (equal parts by volume of 72% perchloric acid and 95% glacial acetic acid) to the test bottle, rinsing the adherent mix off the graduated stem of the test bottle into the body of the bottle while adding the acid. Ensure all the ingredients are at room temperature.
- Immerse the ice cream and acid mixture in water for 5 minutes. Agitate the mixture two to three times during the process to completely digest it. You will observe no color formation at first, but upon digestion there is color progression to tan, brown and finally deep chocolate color. The curd completely dissolves in 1 to 2 minutes. After 5 minutes, the fat will form an immiscible supernatant layer.
- Add enough of the acid mixture to bring the fat into the calibrated stem of the bottle.
- Place the test bottles in balanced pairs in a standard Babcock test centrifuge and run for 2 minutes. If the centrifuge is heated to 60°C., you can read the fat content immediately after removing the sample from the centrifuge. However, if you use an unheated centrifuge, temporarily immerse the test bottles in a water bath ( 50°C – 60°C / 130°F – 140°F) for 5 minutes before reading. You can add glymol for a distinct separation between the supernatant and the digested mass.
- After the test, pour the contents of the test bottle into a reservoir of water before disposing in a sink drain. Rinse the bottle with hot water for the next test. The acid mix dissolves all calcium salts in the sample hence no deposition in the inner walls of the test bottle expected.
- You are dealing with acids; precautions taken when dealing with mineral acids for the unmodified Babcock method applies.
- The mixture of perchloric acid and acetic acid is not hazardous and does not deteriorate under storage.
- Butterfat is as insoluble in aqueous perchloric acid as it is in aqueous sulfuric acid.
- You don’t need to add water to the mix since centrifugation takes only two minutes.