Characterization of Furcellaran-Whey Protein Isolate Films with Green Tea or Pu-erh Extracts and Their Application as Packaging of an Acid-Curd Cheese

摘要

In recent years, there has been a serious need to develop and test new biodegradable packaging. Therefore, furcellaran (FUR) and whey protein isolate (WPI) films containing pu-erh (PE) or green tea (GT) extracts were prepared in this study. The effect of the extracts on the structure, rheological and mechanical properties, and antioxidant and antimicrobial activity of FUR/WPI films was tested. The films were applied as packaging of an acid-curd cheese (quark). Water content, pH, water activity, and microbiological and organoleptic quality of cheese were examined. The storage loss modulus increased with the PE addition as well as tensile strength (by 1.37 MPa) and antioxidant activity (by 42.5 percentage points). The GT addition caused no changes in rheological properties but did affect tensile strength (an increase by 1.33 MPa), elongation at break values (a decrease by 7.08 percentage points), and antioxidant activity (an increase by 39.33 percentage points). The FUR/WPI with GT revealed bacteriostatic effect against Staphylococcus aureus. The number of Lactococcus and total bacteria count decreased in almost all cheeses during storage (approximately by 1-2 log cfu g(-1)), except FUR/WPI + PE. The yeast count increased during storage in all samples (approximately by 4.3-5.5 log cfu g(-1)), regardless of packaging used. Most of the examined films had a negative influence on organoleptic quality of cheese, especially after storage. Therefore, they were found not to be appropriate as packaging of an acid-curd cheese. However, this research did enable the obtaining of a new edible film with good mechanical properties-the FUR/WPI + PE film.