[Australia] Cheese remains one of the most popular dairy products, with most still made using the conventional and most common coagulant, calf rennet, derived from the fourth stomach of a young cow.
However, because of the continuous increase in global cheese consumption, the supply of calf rennet cannot meet the growing demand for cheese production.
Researchers have started to identify alternatives for rennet such as pepsin from chicken, bovine and porcine, proteases from fungal, microbial and plant sources, as well as recombinant chymosin, produced using genetically modified microorganisms.
However, the application of rennet and its substitutes still has some issues.
Rennet and animal pepsin are not vegetarian-friendly and may be rejected on religious or ethical grounds. The use of recombinant chymosin from genetically engineered organisms could cause consumer concern.
Fungal and plant proteases often have excessive proteolytic activity, which can lead to the development of bitter flavour in the end product.
Therefore, the search for alternative milk-clotting proteases applicable for cheese making is still continuing.
The marine ecosystem represents an abundant and diverse resource for obtaining food ingredients, including enzymes that are suitable for cheese making and other applications. Until recently, there have been a few studies on the utilisation of marine enzymes such as those from jellyfish, sponge and seafood waste. However, the application of macroalgae as a source for milk-clotting proteases that can be useful in cheese production has not been explored.
This study describes the properties of cheese made of protease from the edible macroalga Gracilaria edulis, a red seaweed found abundantly in the oceans, especially in the Indo-Pacific region.
The cheese was then compared with the traditional cheese made from calf rennet.
As a new source of milk-clotting enzyme, G. edulis protease showed a high ratio of milk clotting over caseinolytic activity, indicating that the enzyme had an excellent milk-clotting property.
This seaweed protease was used to make a cheddar cheese using the same recipe as the conventional calf rennet cheese, including the steps, the amount of starter, calcium chloride and salt, except three conditions.
Firstly, the coagulation temperature is set to 50 degrees Celsius. Secondly, the cooking temperature of the curd is 50°C. Thirdly, the coagulation time is one hour, slightly more than cheese made from calf rennet (40 minutes).
Because both of the temperatures of coagulation and curd cooking are in relatively high temperatures, the fat in the milk was melted and floated to the surface of the curd. The fat was then carried out into the whey and produced a paler and brighter colour of sea cheese than that of calf rennet cheese (see Figure 1).
The cheese colour was compared using a colourimeter. The colour presented in L, a and b value which indicates lightness, red-green and yellow-blue coordinates, respectively.
From the result presented in Table 1, it can be concluded that sea cheese has a lighter colour, more green and less yellow compared with calf rennet cheese.
The pH of the sea cheese (6.4) was higher than that of calf rennet cheese (5.8). It is also interesting that the yield of the cheese (130 gram cheese/litre of milk) was 13 per cent higher than the calf rennet cheese (108 gram cheese/litre of milk) although from the moisture analysis the sea cheese had more moisture of 53pc while the calf rennet cheese was 39pc.
Table 1 presents the comparison of some attributes of the sea and calf rennet cheese.
The texture analysis showed that the cheese made from the seaweed protease was softer and less chewy than the calf rennet cheese but had the same springiness.
This study shows that the seaweed protease is suitable for making hard cheese type, resulting in a ‘sea cheese’ with less acidity, higher yield and characteristics quite distinct from conventional cheddar cheese.
The project forms part of the PhD project of Ariestya Arlene Arbita. The project is being conducted in Food Science and Technology, School of Chemical Engineering, UNSW Sydney, supervised by Dr Jian Zhao and Dr Julian Cox from the University of New South Wales, and Dr Nicholas Paul from the University of the Sunshine Coast. Ariestya Arlene Arbita is funded by an LPDP Scholarship from the Indonesian government.
Photo: Ariestya Arlene Arbita in front of her poster explaining how she made cheese using a different coagulant extracted from seaweed.
View original article at: Research identifies seaweed extract with potential in cheese making
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