Fatindrymatter FDM

As the FDM level of low-moisture Mozzarella cheese (LMMC) [146] increases, the channels within the cheese structure become larger and more tightly packed with fat globules, which results in greater fat volume expansion, coalescence and pooling of liquid fat during melting. Higher fat content also causes greater interruption of protein-to-protein interactions among fibres, enabling them to collapse and flow more freely on heating, which facilitates the flow and merging of liquid fat pools into even larger pools. Free oil formation in LMMC, therefore, increases with increasing FDM content. It is important to note, however, that free oil increases in an exponential rather than linear manner in relation to FDM (Fig. 1). In general, the rate of production of free oil increases very gradually with increasing FDM between about 10% and 30%, more rapidly between 30% and 40%, and extremely rapidly above 40%. Therefore, LMMC with high FDM is highly prone to the production of excessive free oil on melting. On the other hand, small reductions in FDM in the range of 50-40% can achieve surprisingly large reductions in free oil formation. Alternatively, free oil in LMMC with high FDM can be reduced by using homogenised [32] cream to standardise, in part or in total, the fat content of the milk before cheesemaking. Homogenisation of cream produces smaller fat globules that remain more finely dispersed throughout the cheese structure during stretching and are thus less prone to coalesce into pools of liquid fat.

At the low end of the normal FDM range, LMMC generally forms limited free oil on melting because the channels are smaller and less closely packed with fat globules, which limits their coalescence and pooling. The paracasein fibres are also less interrupted and thus more tightly bonded, therefore they collapse and flow less readily. Inadequate release of free oil favours excessive

Low-moisture Mozzarella cheese (LMMC) 327 25 -1 ,

FHM jft|

Fig. 1 Relationship between fat-in-dry matter (FDM) content and free oil (FO) formation in Mozzarella cheese. Samples (n = 144) varied widely in composition and age and included both commercially and experimentally produced cheeses.

FHM jft|

Fig. 1 Relationship between fat-in-dry matter (FDM) content and free oil (FO) formation in Mozzarella cheese. Samples (n = 144) varied widely in composition and age and included both commercially and experimentally produced cheeses.

dehydration, case-hardening and excessive browning at the cheese surface during baking [155]. Generally, LMMC with >30% FDM produces enough free oil to avoid this problem but excessive dehydration is very common in reduced-fat cheeses with lower FDM. The effects of inadequate free oil formation can be mitigated at the time of baking by spraying a thin layer of edible oil on the cheese surface, which creates a hydrophobic barrier, or by combining a small amount of shredded or comminuted cheese with a high FDM level that oils off readily with the reduced-fat LMMC.

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