M:Food Microbiology & Safety Effect of Grape Pomace Extracts Obtained from Different Grape Varieties on Microbial Quality of Beef Patty Osman Sagdic, Ismet Ozturk, Mustafa Tahsin Yilmaz, and Hasan Yetim Abstract: Grape pomace extracts were obtained from 5 different grape varieties grown in Turkey. The extracts were concentrated to obtain crude extracts; and incorporated into beef patties at 0% (Control), 1%, 2%, 5%, and 10% concentrations to test their antimicrobial effects in different storage periods (first, 12, 24, and 48 h). The numbers of microorganism were generally decreased by the extract concentration during the storage period. All the microorganisms tested were inhibited by the extract concentration of 10% in all the storage periods. Furthermore, the foodborne pathogens including Enterobacteriaceae and coliform bacteria, and the spoilage microorganisms including yeasts and moulds and lipolytic bacteria were also inhibited by 5% of Emir, Gamay, and Kalecik Karasi varieties in beef patties. Considering the results, the extracts of grape pomaces might be a good choice in the microbial shelf life extension of the food products as well as inhibiting the food pathogens as the case of beef patties. Keywords: beef patty, grape pomace extract, inhibitory effect, microbial characteristics Practical Application: Grape pomace consists of seeds, skins, and stems, and an important by-product that is well known to be the rich source of phenolic compounds, both flavonoids and non-flavonoids. These substances have considerable beneficial effects on human health. The use of natural antimicrobial compounds, like plant extracts of herbs and spices for the preservation of foods has been very popular issue because of their antimicrobial activity. Therefore, grape pomace should be added into some food formulations to benefit from their protective effects. In this respect, this study reports the effect of addition of grape pomace extracts obtained from different grape varieties on microbial quality of beef patty. The results obtained in this study may be useful for food industry, which has recently tended to use natural antimicrobial sources in place of synthetic preservatives to prevent microbial spoilage. Introduction There has been increasing trend in usage of natural alternatives to produce foods with longer shelf life and a high degree of safety by protecting them from food-borne pathogens. There are a large number of different types of antimicrobial compounds that play an important role in the natural defense of all kinds of living organ- isms. Currently, in this respect, there has been a growing interest to use natural antimicrobial compounds, like plant extracts of herbs and spices for the preservation of foods because of their antimi- crobial activity (Jayaprakasha and others 2003). Other sources of antimicrobial compounds are some food processing by-products like grape seed and pomace extracts. Grapes have been reported to be the rich source of phenolic compounds, both flavonoids and non-flavonoids (Negro and others 2003; Pinelo and others 2006; Arnous and Meyer 2008; Poudel and others 2008). Grape seeds are also considered to be the rich sources of monomeric phenolic MS 20110295 Submitted 3/7/2011, Accepted 7/1/2011. Authors Sagdic, Ozturk , and Yetim are with Engineering Faculty, Dept. of Food Engineering and author Yilmaz is with Safiye Cikrikcioglu Vocational College, Dept. of Food Tech- nology, Erciyes Univ., 38039, Kayseri-Turkey. Direct inquiries to author Sagdic (E- mail:osagdic@erciyes.edu.tr). compounds, such as (+) -catechins, (–) –epicatechin, and (–) -epicatechin-3-O-gallate and dimeric, trimeric, and tetrameric procyanidins acting as antimutagenic and antiviral agents (Saito and others 1998). Therefore, these compounds may potentially interact with biological systems and play a significant role in the preventing human neurodegenerative disorders, cardiovascular dis- eases and some cancers (German and others 1997; Poudel and others 2008). The pomace, consisting of seeds, skins, and stems, is an im- portant by-product of winemaking industry and the production of traditional foods like molasses and vinegar (Ozkan and oth- ers 2004). Grape seed is well known to contain polyphenols in considerable levels, which makes it a functional product showing some potential health benefits. Therefore, grape pomace should be added into food formulations to take advantage of the health effects of phenolic compounds. However, no adequate study has appeared on the antimicrobial effects of these extracts on food spoilage microorganisms and foodborne pathogens although grape seed and pomace extracts are confirmed as rich sources of phe- nolic compounds. Some studies tested the antibacterial activities of pomace and seed extracts using paper disk and agar well dif- fusion methods (Gokturk-Baydar and others 2004; Ozkan and others 2004); however, these studies were on the antibacterial ac- tivity of pomace extract against in vitro test organisms, not on the C  2011 Institute of Food Technologists R  doi: 10.1111/j.1750-3841.2011.02323.x Vol. 76, Nr. 7, 2011  Journal of Food Science M515 Further reproduction without permission is prohibited