Comparison of Cinnamon Essential Oils from Leaf and Bark with Respect to Antimicrobial Activity and Sensory Acceptability in Strawberry Shake.

Cinnamon leaf and bark essential oils have long been used as natural preservatives and flavoring agents in foods. This study determined antimicrobial effects of leaf and bark of cinnamon essential oils (CEOs) against 2 foodborne pathogens, Salmonella Typhimurium (S.T.) and Listeria monocytogenes (L.m.), at 2 initial bacterial levels (4- and 9-log CFU/mL) in strawberry shakes. The antimicrobial study of CEOs at 0.1% and 0.5% in strawberry shakes against S.T. and L.M. showed a significant difference (P < 0.05) in log reductions of both bacterial growth at low (4-log CFU/mL) and high (9-log CFU/mL) initial bacterial levels. Addition of 0.5% CEOs into strawberry shakes at 4 °C completely inhibited both bacteria after a period of 8 d storage. Shelf-life study showed that acidity and total solid content were not affected during storage. The strawberry shakes containing bark CEO had higher ratings of sensory acceptability compared to leaf CEO, with or without the addition of 1% masking agent. In conclusion, this study demonstrated that CEO derived from bark was better than that from leaf in terms of their antimicrobial activity and sensory aspect. PRACTICAL APPLICATION: This study demonstrates that essential oils derived from cinnamon bark and leaf have the potential to be used as natural antimicrobial ingredient in milk beverages with respect to sensory aspect. This finding promotes the acceptance of natural antimicrobials among consumers, while providing enhanced safer products to the food industry application.

Antimicrobial Activities of Phenolic Extracts Derived from Seed Coats of Selected Soybean Varieties.

Soybean hulls or seed coats consist of complex carbohydrates, proteins, lipids, and polyphenols such as anthocyanidins, proanthocyanidins, and isoflavones. The polyphenolics in the seed coats give them various colors such as black, brown, green, yellow, or even a mottled appearance. In this study, the antimicrobial effects of phenolic extracts from the seed coats of different colored soybeans (yellow, dark brown, brown, and black) were evaluated against foodborne pathogens such as Salmonella Typhimurium, Escherichia coli O157:H7, and Campylobacter jejuni in broth-cultures as well as on chicken skin. The highest total phenolic content was observed for the phenolic extract from soybean variety (R07-1927) with black colored seed coat (74.1 ± 2.1 mg chlorogenic acid equivalent [CAE]/g extract) and was significantly different (P <0.0001) from the extract of the conventional soybean variety (R08-4004) with yellow colored seed coat (7.4 ± 1.2 mg CAE/g extract). The extract from black colored soybean produced reductions of 2.10 ± 0.08 to 2.20 ± 0.08-log CFU/mL for both E. coli O157:H7 and C. jejuni after 3 d when incubated in broth-culture having 4-log CFU/mL of bacteria, whereas a 6 d incubation was found to reduce S. Typhimurium and E. coli O157:H7 at 2.03 ± 0.05 and 3.3 ± 0.08-log CFU/mL, respectively. The extract also reduced S. Typhimurium and E. coli O157:H7 attached to chicken skin by 1.39 ± 0.03 and 1.24 ± 0.06-log CFU/g, respectively, upon incubation for 6 d. Soybean seed coat extracts may have a potency as antimicrobial agents to reduce foodborne bacteria contaminating poultry products.

Influence of acid-adaptation of Campylobacter jejuni on adhesion and invasion of INT 407 cells.

The aim of this study was to determine the influence of acid-adaptation on the survival as well as adhesion and invasion of human intestinal cells by nine Campylobacter jejuni strains after exposure to different stress conditions. Acid-adapted and nonadapted C. jejuni were exposed to different secondary stress conditions such as acid (pH 4.5), starvation (phosphate-buffered saline, pH 7.2), or salt (3% wt/vol NaCl). After exposure to the secondary stress, the adhesion and invasion abilities of the strains were evaluated in vitro in tissue culture using the human intestinal cell line INT 407. The survival rates of acid-adapted cells of some strains of C. jejuni exposed to different secondary stresses were found to be significantly higher than the non-acid-adapted cells. Similarly, some strains also showed an increase in adhesion and invasion (p<0.05) when acid-adapted C. jejuni were exposed to stresses such as acid, starvation, or salt as compared to non-acid-adapted C. jejuni. We found that adaptation to acid stress can enhance the survival of C. jejuni when exposed to secondary stresses and, thus, result in increased adhesion and invasion of human intestinal cells in vitro. However, the survival rates as well as the degree of adhesion and invasion were found to vary with the strain of C. jejuni, the time of adaptation to acid, the type of the secondary stress and exposure time to the secondary stress. These results show that adaptation to stresses could influence virulence of C. jejuni. Understanding the conditions by which C. jejuni adapts to stresses will provide information concerning how this organism is able to survive inside and outside the host. This, in turn, could offer methods to reduce or eliminate C. jejuni in the environment.