|The sensory characteristics of food, in particular the flavours of food, play a very crucial role in the food industry. It is often what consumers associate most from food, and it is therefore crucial for food manufacturers like The Tatua Co-operative Dairy Company to produce flavour ingredients that are unique and of the highest quality.
The Dairy Flavour Ingredients Business Unit at Tatua produces a range of dairy flavour ingredients including Butter, Cream and Milk, and Cheese Flavours. Tatua exports most of their flavour products worldwide to various food manufacturers, enhancing the flavour of the products that such manufacturers produce. Umami or savouriness is one of the five primary tastes. It is one of the most important flavour characteristic in dairy flavourings. In particular, umami is most needed in many of the different cheese flavourings produced by Tatua.
This project focuses on optimising the release of glutamate from casein. Liberated glutamate with a commercial name HCP337 is used as a flavour enhancer, increasing the umami of the dairy flavourings that Tatua makes. Alternatively, the addition of monosodium glutamate (MSG) can also increase the umami of the flavours that Tatua makes, however this is not possible due to a couple of reasons: MSG has a negative reputation in the consumers’ mind, as many believe consumption of MSG can cause negative health effects; another reason is that addition of MSG would prevent Tatua from labelling their products as “natural”. Thus, the glutamate used for Tatua’s flavour ingredients is derived from the proteolysis of casein.
Currently, the problem is that very little free glutamate is present in the HCP337 product even after a very long proteolysis. Therefore, the purpose of this project is to comprehensively examine the biochemistry of glutamate release in order to find the optimum proteolysis condition and use this knowledge to optimise the current process, increasing glutamate release.
Three techniques were developed over the initial part of the study to quantify glutamate, glutamine, and pyroglutamic acid. A thorough set of samples from the HCP337 production process were then characterised. We found that indeed there was low glutamate content in the HCP337 product, and there was pyroglutamic acid in significant amounts. Stability tests of both glutamate and glutamine showed that glutamate is stable and not affected by the processing conditions. On the other hand, glutamine is very unstable and converted into pyroglutamic acid spontaneously under the processing conditions.
With this information, various tests were performed with the focus of maximising glutamate yield from casein. These tests included: testing the proteolytic capacity of new and different enzymes at differing pH values with the hope of finding a better and more suitable enzyme at liberating glutamate from casein, the use of different acidifying agents in the HCP337 production process, and the screening of glutaminase activity within the new enzymes. The presence of glutaminase may further increase the glutamate yield, as glutaminase will convert the free glutamine released into glutamate instead of it spontaneously forming pyroglutamic acid.
In summary, this study demonstrated that the current HCP337 production process is not designed to optimally release glutamate from casein. Altering the pH and enzyme combinations during hydrolysis did not appear to be effective strategies to increase glutamate release from casein. More tests on more enzyme should be conducted in the future in order to find enzymes that are most effective at releasing glutamate under the appropriate production process.