This blog is a continuation of our Good Manufacturing Practices/Making Jams and Jellies. As discussed before, consistency is extremely important. Therefore your ingredients need to be consistent. Let’s start with fruit, peppers or whatever your taste base is for your recipe.
Fruit: Using an IQF (individually quick frozen) product is the most consistent. Packing houses that product IQF products have a range of sugar content that they use in order to give you a consistent product. However, if you change your IQF provider make sure they provide you with a specification sheet including average sugar content and pH. If they cannot provide you with that information, you might want to consider using a packing house that can. If you have no choice but to use a product that you cannot get specifications for, then you will need to test in house. You always have the option of just trying the product and hope that it works. My goal in writing this blog is to take the “maybe it will work” out of the equation. I recommend two instruments that if used properly will all but end production failures.
1. Refractometer: I recommend the Atago Master 93H (45 to 93 brix) and Atago Master 50H (0 to 50 brix). Both meters are temperature compensated, heat and water resistant. This means they are very accurate and can measure hot liquid during the cooking process. Easy to clean and generally no calibration required. If you think the meter might be reading incorrectly, you can simply use a 50/50 solution of distilled water and sugar for accuracy test. If the meter is reading incorrectly, there is an adjustment screw on the bottom of both meters. A little twist will make the correction. I have used these meters for 20 years and sold hundreds of them to my customers. I have never had to adjust my personal meters and in 20 years had to adjust only one of my customers.
2. pH Meter: For a good entry level meter I recommend the Oakton pH tester 20. Good accuracy with a relative low cost (under$300.00). A bench top meter would be the next step. Very Accurate. Meter base and electrode are separate. Price starts at $600.00 and up. Both meters will require the purchase of buffer 4 and buffer 7 solution for calibration. Both meters require close attention to maintenance. The Oakton meter has a built in bulb that must be cleaned correctly and stored in buffer solution to maintain accuracy and longevity. The same goes for the bench top model probe. I am not recommending a specific bench top model. As long as it is a reputable company like Beckman and the like, you will be fine. My only recommendation for the benchtop model is that it is temperature compensated with an accuracy of +-.02 or better.
With the understanding that we know how to use our meters, we can test are incoming fruit and have certainty that the fruit is in specification. I will use strawberries as an example. Strawberries you have been using have and average brix of 8 and pH of 3.4 . You change strawberry supplier and now the strawberries are at a brix of 9 and a pH of 3.9 . The brix going from 8 to 9 is not a problem. A small adjustment to take out a little sugar from the recipe could be done to keep the end brix exact. The pH going from 3.4 to 3.9 is a problem. In general when using our SSP pectin, any fruit with a pH of 3.2 to 3.4 will not need any additional acid to ensure a proper gel. Fruit with a pH of 3.9 will require the addition of acid (usually citric acid) to achieve a proper gel.
Let’s go the other direction. Let’s say your strawberries have a brix of 7 and a pH 2.9 . A small adjustment adding a little sugar will take care of the brix. A fruit with a pH of 2.9 can cause several problems. Too much acid will raise the set temperature possibly causing a pre-set(soupy texture/gel) and or water separation to name a few. To stop this problem will require either taking out acid that is already in the recipe (lemon juice or citric acid) or the addition of a buffer (sodium citrate).
By knowing the brix and pH of your fruit will allow you to make adjustments if needed before production greatly reducing the risk of failure.
What we have discussed here is all the more important if you are using fresh fruit.
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