NIZO – CheeseCoat project: Novel processing technology for manufacturing low- fat mozzarella-type cheese in ready meals

NIZO developed novel technologies for manufacturing low fat (3%) mozzarella type cheese with superior performance in ready meals. The result is 3.5% fat prototype LMMC’s, showed desired properties without off-flavours.

Executive Summary

The CheeseCoat technology enables production of Mozzarella-type cheese with very low fat content, still giving the texture, melting behaviour and flavour desired by the consumers when used in baked ready meals, such as pizzas. Over the last three years, research institutions, SME associations, and food industry have been working together in a research project funded by the European Commission with the aim to increase the competiveness of small and medium sized enterprises by developing innovative products.

The CheeseCoat project has been focusing on combining a number of innovative strategies to increase the performance of low fat cheese. These include smart and strategic selection of the starter and adjunct cultures used in the cheese production by screening a large number of starter cultures for properties such as proteolysis and EPS forming capacity and using specific growth media and conditions for scale up. In addition, a specific processing protocol devoted to increase the properties of low fat cheese have been developed by the researchers and transferred to the cheese manufacturer in the consortium, in combination with the innovative starter cultures. By using this approach a significant improvement in the properties of the low fat cheese was discovered including texture, meltability and flavour.

In order to increase the performance further, a coating based on only dairy-derived ingredients were developed in parallel. It was shown that adding a small amount of fat-based coating to the surface of shredded cheese, significantly enhanced the melting behaviour and performance off low-fat cheese upon baking. As it was discovered that a non-homogenous distribution of the fat droplets on the cheese surface was sufficient for increasing the melting, the research associated with the coating formulation focused on developing an innovative coating formulation that was based on only dairy-derived ingredients, that was sprayable and easily cleaned of processing equipment, as well as effective in increasing the performance of low-fat cheese.

It was established that 2.5wt % of the developed coating is sufficient for increasing the melting behaviour of low fat cheese. As the coating also contains water, the coating only adds around 1wt % fat to the cheese, but gives the melting behaviour of full-fat cheese. After establishing the coating formulation a completely food-grade, spray-coating equipment for application of the coating off low fat cheese was designed, developed and manufactured by the CheeseCoat partners. This was validated at the pizza factory of 2 Sisters Food group (former Northern Foods) using the cheese developed within the project with the specific starter cultures and manufacturing protocol as well as the emulsion coating. Pizzas were baked and evaluated by consumer panels. The results developed within the CheeseCoat project show that the total fat content of a pizza can be reduced by at least 50% by using the CheeseCoat technology, without influencing the consumer experience.The CheeseCoat consortium is now ready to take the next step with this innovative technology and start commercializing the product.

Project Context and Objectives

The concept of the CheeseCoat project was to develop a new Mozzarella-type cheese with very low fat content, still having the same texture, melting properties and flavor as full fat cheese when used in ready meals, such as pizzas. The objective was to obtain this using a combination of innovative approaches including screening and smart selection of starter cultures, optimization of the processing protocol and development of a coating technology for shredded cheese.
In order to meet the goals outlined above the work was divided into a number if Work Packages (WPs) with more specific objectives as outlined below. WP 1, 3 and 5 worked with cheese development and production whereas WP 2, 4 and 6 focused on development and validation of the coating technology. WP 7 and 8 focused on dissemination and exploitation related activities and WP 9 on consortium management.

• Investigation of novel starter and adjunct cultures for low-fat Mozzarella cheesemaking (WP 1).
• Pilot-scale production of novel starter/adjunct cultures for making low-fat Mozzarella cheese (WP 3).
• Manufacturing and testing of cheese (WP5)
• Investigation of the oil coating process (WP2)
• Development of oil-coating machine and control system (WP 4)
• Coating technology validation and testing (WP 6)
• Innovation related activities including exploitation (WP 7)
• Training and dissemination (WP 8)
• Consortium management (WP 9)

Project Results

The product in focus in the project was low-moisture mozzarella, widely used in the food-service industry. The starting point in this project was the aim to cut the fat content in low fat mozzarella type ingredient cheese to less than 3%, e.g. for pizza and ready meals, without losing the attractiveness to the consumer. The properties of the low fat mozzarella cheese available presented poor hot and cold functionality: Cheeses were tough and brittle, gave shattered, small shreds, upon baking in the oven they did not spread sufficiently but readily dried out, browned excessively and lacked chewiness and stretchability when eaten.
As a first step the target properties of low-fat mozzarella needed to be defined, and the following criteria were identified:

• Low fat, <3%
• Shreddable when cold
• Melting when heated.

These properties as well as other characteristics were quantified for a set of bench mark cheeses: full fat standard mozzarella, mozzarella with 15% fat and with 10% fat. The characteristics included e.g. moisture/protein ratio, degree of hydrolysis, meltability, microstructure, calcium content and stretchability. These gave the project a target profile to work towards when developing an improved low fat mozzarella with <3% fat. In order to reach this goal it was clear that difference measures would need to be taken. A literature survey was undertaken and the results combined with the experience of the team to device the routes for the development. The work in the project was defined in different work packages, dealing with different essential steps in the development: culture selection, process development, culture optimization, fat coating development, pilot scale manufacture, development of a coating machine, and demonstration of the cheese, coating and machinery in a food production environment.

Culture selection

A good cheese culture should provide acidification at sufficiently high rate and extent, and degradation of the protein to contribute to texture and flavour. Partial degradation of the casein matrix (proteolysis) is a prerequisite for good melting properties of cheeses, and this is particularly essential when the fat content of the cheese is low. The main drawback is that too much proteolysis may lead to over-soft cheese, low stretch length, strong browning, short shelf life, and) off-tastes (bitter, musty, meaty, etc). Correct balancing and control is thus the challenge in culture selection and development. For a cheese producer the choice of cultures is a convenient and flexible variable to influence proteolysis and cheese ripening.

The main work regarding culture selection was carried out by NIZO Food Research, using the MicroCheese model that enables efficient screening of culture performance. Overall, more than 100 strains and combinations of strains were screened for their properties regarding proteolytic capacity, their EPS (extracellular polysaccharides) forming ability, moisture binding and functional effects. In order to suit the special process of mozzarella some development of the model was required, as it is originally developed for conventional hard cheeses such as Gouda. The heating and stretching used in mozzarella production are essential steps of the process to provide the typical microstructure in mozzarella, and also to provide a relevant moisture/protein ratio. The cheeses produced in this system weigh about 1 g each, and the system can work with 24 cheeses in parallel. Both individual strains and combinations of strains were investigated. Finally, eight strains in total were selected for further development. The strains had shown superior properties regarding proteolysis/melt-enhancement.
In order to understand why some strains showed better performance than other strains, the vast data set collected during strain screening was utilised. To this end advanced data analysis techniques and tools (e.g. cluster analysis and Random Forest classification) were applied for examining and correlating the proteolysis, melting and textural firmness data obtained from the MicroCheese screening trials performed in the project. This analysis pointed out that several casein-derived peptides appeared to be related to the heated functionality of the microcheeses (increase in spread area). The eight selected strains exhibited high capacity to produce such peptides. The selected strains were tested as adjunct cultures together with commercially available cheese starter cultures. Effects of different rennets were also studied. This part of the work allowed also NIZO to further improve their tools for data analyses of large data sets with the objective of finding correlations between different types of data.

Optimisation of cultures

The selected strains were handed over to CSK for further improvement by developing optimized cultivation conditions and media. The viability and performance of the strains are strongly linked to their growth conditions, and therefore it is essential that these are optimised. When comparing the CSK media with standard media, the cells grown in CSK media showed clear signs of improved health due to their improved morphology, such as shorter rods (Lactobacilli) and more elongated chains of cocci (Streptococci). Investigations showed that the optimised media and growth conditions provided cultures with improved activity and viability compared to when grown in standard media. Furthermore, phage-resistance of the strains was confirmed. The selected strains were scaled up and produced as pellets for use in cheese manufacture at SME partner Joseph Heler Cheese.

Process improvements

Not only the strains and their cultivation need to be optimized for the best cheese product performance, but also the cheese making process itself. The traditional method involves several steps that are particular to mozzarella, and to achieve the characteristic string texture. First, the starter culture is added to milk, and the acidification starts. Then rennet is added to coagulate the milk to form curd. The curd is cut in two steps, whereafter it is heated, collected and worked by stretching and kneading. Traditionally this is done by hand, but in an industrial environment this is made using machinery. This process is essential to form the typical stringy microstructure of mozzarella. Most often, mozzarella is encountered as a fresh cheese in whey, but for use in food industry a variety with less water content is used.

This low-moisture mozzarella is firm, shreddable and is usually manufactured as blocks. A pilot scale procedure for the production of 3% fat Mozzarella-type cheese in 200L batch size that comprised a cooking-stretching step, was successfully set up. Processing conditions, milk pre-treatment and ingredients were varied within boundaries implementable for SME partners. Most process variables present a window of desirable performance, with poorer results on either side of this window. The trials were designed to also guide in the selection of the parameter window for different parameters. Most favourable adjustments of processing/recipe resulted in a basis Mozzarella –type cheese, free of off-flavours, with as low as 3% fat and a moisture/protein ratio closely the benchmark full fat Mozzarella.

Different functionality tests showed that this cheese had the desired properties. The choice of starter culture, adjunct culture and rennet influenced the cheese properties. Adjusting the moisture/protein ratio and the extent of casein-whey protein interactions (e.g. by heat treatment of cheese milk) where key factors for steering. Most favourable adjustments of processing/recipe resulted in a basis Mozzarella –type cheese, free of off flavours, with as low as 3% fat and a moisture/protein ratio closely the benchmark full fat Mozzarella.
NIZO worked closely with Joseph Heler to implement the improved mozzarella making process in the pilot scale at Joseph Heler. Different measures were implemented in the cheese making process to improve the moisture/protein ration, the texture of the cheese and the yield. The transfer of knowledge was intense and highly beneficial for the company. CSK also worked in close collaboration with Jospeh Heler in order to make the best use of the newly developed cultures, which supplied form CSK to Joseph Heler. The knowledge gained by Joseph Heler on bacteriophages in the cheese making environment was very valuable. Several series of pilot scale trials were conducted in the project at Joseph Heler, and the cheeses were evaluated for chemical key properties (moisture, protein and fat content, degree of proteolysis), texture and sensory parameters and performance (heated functionality such as melt area and stretchability) at Joseph Heler site and by the research partners.

The cheeses were evaluated both after a short period of storage and towards the end of the typical shelf life on low moisture mozzarella type cheese. In the 3% fat cheeses, the cultures and their combinations yielded different degrees of proteolysis and consequently, in differences in hot functionality (more or less spreading, more or less enhancement of stretchability upon heating). In some cases pizza trials were conducted at 2 Sisters Food group, involving evaluation by panels. The best cheeses showed similar performance as the reference cheese.
From application point of view (pizza baking test), key parameters for good performance of the cheeses were deduced: moisture/protein contents not exceeding 2.0 moderate degree of proteolysis, moderate melt/spread and relatively low forces to stretch the molten cheese were preferred. The results of the project and the cultures delivered allow flexible selection of suitable culture combinations and processing conditions to produce 3.5% fat mozzarella-type cheeses with target functionality parameters defined by the cheese-maker’s customers.

Coatings to enhance melting properties

The fat in cheese is an important component that provides part of the melting properties of cheese, in addition to the properties of the protein-rich parts of the cheese. Under conditions when moisture loss is limited, the melting and flow properties are to a major extent determined by the state of the proteins, e.g. the extent of proteolysis as described in the previous sections. The prevention of moisture loss is essential for ensure that the cheese can melt and flow, e.g. in baking. In cheese with high fat content, the fat in the cheese matrix will act to coat the cheese and to lubricate in the protein matrix. However, in low fat cheese, the fat content is too low to provide these two functions. One way to prevent excessive moisture loss is to apply a coating. Earlier studies have used liquid oils as a surface coating for cheese with successful results, but the overall fat content is easily increased so that the benefits of the low fat cheese are lost. A further drawback is that non-dairy ingredients are added to the cheese. In this project different routes to addition of fat were studied and compared: pure fats, fat based surfactant coatings, and emulsions. Different oils and fats were investigated, although the overriding aim was to develop a coating based on dairy ingredients.
It was soon realized that pure fats provided different melting performance and too high fat additions. Emulsions were then selected as these improve the spraying and coating properties, and also the means to reduce the fat content while still providing a sprayable product. The majority of the studies were undertaken with butterfat and olive oil as fat components, and different proteins as emulsifiers. It was found the emulsions with around 40% fat content stabilized by dairy proteins. These emulsions performed well in melting studies using cheese discs and cheese shreds. Efforts were direct towards formulating and processing an emulsion with sufficient shelf stability from a physical point of view. The emulsion stability was improved by either adding a low amount of olive oil to the butter oil, or by adding a low concentration of a gum in the continuous water phase. The drawback of these control measures is that non-dairy components are introduced. After experimenting with composition and process intensification suing high intensity ultrasound to enhance the emulsification, a stable product (8 weeks at 4°C) was prepared.
The coating development and processing was scaled up at DOMCA (SME partner), using the in-house equipment for emulsification and with the addition of process intensifying measures by high intensity ultrasound. Several pilot scale batches of coating formulations were prepared and investigated for stability. The process intensification was important for improved physical stability of the emulsion. Through the project new processing technology has been introduced at DOMCA, and a new type of product has been tested in the production facility. Further, the overall process hygiene control routine was scrutinized, since ingredients sensitive to microbial contamination are used, and the process control was enhanced. It is possible for DOMCA to add the CheeseCoat coating to their range of products.
In order to gain a deeper understanding of the effects of the coating on the cheese, an in-depth study of the events in the cheese during baking was initiated at SP. A combination of Thermogravimetric analysis (TGA), profilometry, and Confocal Raman Microscopy showed that the location of the moisture loss was identified as the surface layer of a cheese disc, while the interior of the cheese piece was indifferent to the coating when tested in a melting experiment. When applying a small amount of emulsion, incomplete coating of the cheese is obtained, and it was shown that this is still sufficient to support a similar melting behavior during baking as for full fat cheese.
During the course of the project different methodologies for analysis of cheese melting have been established and shared between partners. These methods include melting of standardized cheese discs under different conditions, melting of cheese shreds with image analysis, and melt-stretch of molten cheese. In addition have the research teams developed and adjusted their analytical methods for the application to the needs for low-fat mozzarella cheese. This is overall contributed to the scientific quality and knowledge of the groups.

Technology for spray coating

For full implementation of the new cheeses and coating, a spray-coating machine for continuous coating of cheese shreds was designed by HERI and built by SME partner Boluda Industrial. The machine is a prototype and constructed so that it can be used in a factory environment, including all features for appropriate cleaning possibilities. The construction materials are European approved food grade materials to allow placement in any food manufacturing facility. The design is flexible and can be easily be adapted for different food coating applications using wet coatings, hot or cold. A control system has been designed for hot, cold, dry or wet ingredients and allows for control of each application. The present control systems can be operated manually or pre-programmed with limited setting. If requested by the final user the system can be upgraded with a fully programmable touch screen display linked to a QA system with real time monitoring. The design of the spray-coating machine can be adapted to the specific requirements of the end user, regarding placement in a production facility, capacity, etc. BDI has the facilities to build similar machines for use in food industry and elsewhere.
The function of the machine was tested at HERI, and adjustments of the design were made to improve the performance, ease of cleaning and operating. The prototype machine was placed at 2Sisters Food Group for a demonstration trial, and to optimize the spray system and the conveyor speeds to achieve appropriate coating of the shredded cheese. The machine worked as expected with the spray system providing good coverage of the cheese shreds, and easy handling of spray and cheese shreds.

Demonstration activities

During the project demonstration activities have been performed at HERI for validation trials and at 2Sisters Food Group for trials in the production environment. On both occasions cheese produced wihtin the project using the new cultures were used, together with the novel coating. Thus, the whole system of cheese, cultures, coating and spray-coating machine was tested.
For the validation demonstration at HERI in February 2014 several cheeses with different combinations of the selected carriers was produced in sufficient amounts at Joseph Heler. They experienced good performance of the culture blends in practice, with acceptable acidification rates and manufacturing times. SP provided the coating after scaling up to a scale of several litres. The prototype spray-coating machine, complete with shredder, spray coating chamber and conveyor belts was used. Cheese was shredded and fed through the coating machine and the spary systems was adjusted to give a sufficient coating of the shreds. Proof of concept was provided by pizza baking tests according to the industry standard as set by 2Sisters Food Group. The tasting showed that the most beneficial culture combination, cold functionality and visual appearance of the baked pizza were closed to the full fat reference cheese. The tests indicated some points for improvement in the machine design, which also were implemented before transferring the machine to 2 Sisters Food Group for further trials. This validation demonstration was documented by Euro News, and is available on YouTube http://www.euronews.com/2014/03/03/say-cheese-making-pizza-a-guilt-free-pleasure/
A demonstration in the production environment was performed at 2 Sisters Food Groups with successful results. Some additional points of improvement for use in the production environment were suggested by 2 Sisters Food Group. Several cheese produced at Joseph Heler using the CheeseCoat cultures were used in a mixture with standard cheddar cheese to achieve a similar flavour profile as the conventional products. The baked pizzas were tested by a panel and rated as comparable to the full fat standard pizza. The total fat reduction was 50% for a pizza with the new cheese in combination with standard cheddar!

Potential Impact

It is expected that the results from the CheeseCoat project will have a strong impact on the participating SME associations and their members as well as the other partners included. By the innovative strategies for production of functional low fat mozzarella-type cheese, developed within the project, the partners having access to the project results will significantly increase their competiveness on the European market, and potentially beyond.
CheeseCoat offers an innovative technology which will benefit a large SME community in the cheesemaking and dairy industries. The ingredient cheese market in Europe is about 1.2 mio tons annually (2010), with a growth rate of 4-6% annually (Gira presentation, 2014) and employs an excess of 50,000 European citizens. In the European market (and the worldwide market in general), Mozzarella cheese is the main ingredient cheese with a market of 450 thousand tons annually in Europe (2010). The ingredient Mozzarella market is increasing at a rate of 5-9% with the major target markets being frozen and chilled pizzas, ready meals, the retail market (as shredded) and food services (e.g. pizza shops, etc.). There is particular space for growth in the eastern part of Europe, where the use of ingredient cheese is currently smaller part of the market than in western Europe (GIRA presentation, 2014)
We believe that our new low-fat cheese will not only benefit the ingredient cheese sector but
also the wider cheese and dairy sectors. We foresee several sectors where we will be able to utilise the low-fat and healthy image of our cheese product. These include the industrial cheese sector (ready meals and frozen/chilled pizzas), the foodservices sector (including fast food) and the retail market (where cheese will be sold as shredded). This will provide the opportunity for our cheese manufacturing SME community to gain access to new markets which are currently serviced by LE cheese manufacturers with little competition. Large food companies usually buy their ingredient cheese from large dairy and cheese companies such as Glanbia, Arla and others. Our CheeseCoat technology will provide our ingredient cheesemaking SMEs with the opportunity to have access to an innovative low-fat cheesemaking technology which will allow them to compete with large companies. In order for the LE-dominated industrial cheese sector to achieve its targets, it will have to rely on our SME cheese suppliers who will manufacture provide them with low-fat cheese.
The access of a functional low-fat cheese for use in e.g. pizzas and ready meals opens up for new and healthier products to provide the European consumers with a wider choice of healthy ready meals, which is an asset in a society where such meals have a growing market share. Since obesity is increasing it is essential that healthy and attractive choices are available in the convenience food segment. Since taste, eating experience and appearance are primary factors for food choice, these aspects must not be underestimated in the development of healthier food products. The development in the project has shown that the fat content of a standard pizza can be cut by 50% and still be attractive to the consumer. There is also potential for further reduction of the fat content by modifying the CheeseCoat low-fat mozzarella to full fat cheese, and working with the CheeseCoat coating.
The three SMEs in the project have gained extensive experience and new technologies that can be used to enhance present products and develop new products. This will support the growth potential of these companies, ultimately leading to new European jobs. The results of the project are owned together with the SME associations, which have been very active in disseminating the project. Thus, they have paved the way for introduction of the CheeseCoat concept with other SMEs and large companies as licensees to the technologies. This has the potential of introducing the new low fat mozzarella cheese in markets and countries not represented in the project, and thus enabling a larger consumer market to be reached by new and healthier convenience food products.
Joseph Heler Cheese, the only cheese manufacturer included in the CheeseCoat consortium, have significantly benefited from the project by improving the process for development of low-fat cheese, both by optimizing the current process protocol but also gaining access to specific cultures. By this, Joseph Heler is expected to increase the market share in both the low fat and reduced fat cheese market.
BDI, will benefit from the project by commercializing the spray-coating equipment. This machine was designed not only to fit the purpose of the CheeseCoat technology but also to be used in other food-related coating applications. BDI is therefore expected to significantly increase their business towards the food industry.
DOMCA will benefit from the project by being able to commercializing the fat-based emulsion coating for low-fat and reduced cheese applications. This is expected to increase their market within food coatings significantly. DOMCA has further gained insight in novel emulsion processing technology (HIU) that can be applied also to other products in their portfolio.
The SME-associations and their members will benefit by entering into a joint ownership with the SMEs.

List of websites:
www.cheesecoatproject.com

(Source: https://cordis.europa.eu/project/id/286819/reporting/pl)