*3.3. Polyphenols*

Although polyphenols are water-soluble, most were found in the curd but very few in the whey (Figure 1).

**Figure 1.** Total polyphenol content of cheese and whey produced with kiwifruit extract and calf rennet. (**a**) Buffalo milk; (**b**) sheep milk. \*\*\* *P* < 0.001

Cheeses obtained with the kiwi extract showed a significantly higher content of polyphenols, both in buffalo (+466%) and sheep cheeses (+278%) (Table 3).



BMC, buffalo–calf rennet cheese; BMK, buffalo–kiwifruit cheese; SMC, sheep–calf rennet cheese; SMK, sheep–kiwifruit cheese; SEM, standard error medium; S, significance. \*: 0.01 < *P* < 0.05; \*\*: 0.01 < *P* < 0.001; \*\*\*: *P* < 0.001; ns: not significant; ne: not estimable.

The polyphenol content of SM-C was high, because the sheep milk used for our experiments was obtained from grazing animals. Our results are in line with Hilario et al. [29] in cheese produced with milk from pasture fed goats.

Cheeses obtained with the kiwifruit extract were higher both in flavonoids (quercetin, rutin and catechin) and in phenolic acids (caffeic acid, coumaric acid and cinnamic acid). They also contained coumaric and cinnamic acids, which were not present in the calf rennet cheese. The only polyphenol not affected by the cheesemaking was gallic acid.
