Effect of Microencapsulation on Chemical Composition and Antimicrobial, Antioxidant and Cytotoxic Properties of Lemongrass (Cymbopogon flexuosus) Essential Oil

Research background

Lemongrass (Cymbopogon flexuosus) essential oil exhibits antimicrobial and antioxidant properties due to the presence of α-citral and β-citral. Essential oils are susceptible to volatilization and oxidation when applied to food matrices. Therefore, a barrier is needed to protect this material. The present study aims to produce microparticles containing lemongrass essential oil, with gum arabic and maltodextrin using spray drying technology.

Experimental approach

Lemongrass essential oil was extracted by the hydrodistillation method and later microencapsulated with different wall materials. Free and microencapsulated lemongrass essential oil was evaluated for the cytotoxic activity (using Artemia salina as test sample), chemical composition (GC-MS), encapsulation efficiency, antioxidant activity (DPPH, ABTS and FRAP), antimicrobial activity and minimum inhibitory concentration.

Results and conclusions

The lethal concentration (LC₅₀) of lemongrass essential oil in the cytotoxic test was 8.43 μg/mL against Artemia salina; a high activity that can be associated with the presence of α-citral (~33%) and β-citral (~21%) in the samples, since these were the main compounds with bioactive properties. The highest value of microencapsulation efficiency (88.11%) was obtained when only gum arabic was used as wall material. In general, the microparticles showed satisfactory antioxidant activity (expressed as Trolox equivalents, between 348.66 and 2042.30 µmol/100 g) and bactericidal effect in vitro against Gram-positive and Gram-negative microorganisms. In conclusion, the microencapsulated lemongrass essential oil is a promising functional additive in the food and pharmaceutical industries.

Novelty and scientific contribution

This study shows that microparticles containing lemongrass essential oil can be prepared using gum arabic and maltodextrin as wall materials by spray drying, resulting in high microencapsulation efficiency. The drying process maintained the antimicrobial and antioxidant properties of the essential oil. Therefore, the microencapsulated lemongrass essential oil is considered a natural, functional and promising additive in the food industry. Its antimicrobial action can increase the shelf life of fresh and semi-fresh products such as cheese, yogurts and meat products. In addition, its antioxidant action can delay the lipid and protein oxidation in food products.

Characterization and application of Croton blanchetianus Baill extract for lamb ribs preservation

This research evaluated the antioxidant, antimicrobial and toxicity potential of the leaf extract of Croton blanchetianus Baill (ExCb) and its effect on the conservation of lamb ribs. The ExCb (control treatment) revealed higher concentration of 2,5-dihydroxybenzoic acid (190.10 mg/g), catechin (84.10 mg/g), rosmarinic acid (56.01 mg/g), 4-hydroxybenzoic acid (52.05 mg/g) and myricetin (40.00 mg/g). And it showed high phenolic content (204.05 mg GAE/g), antioxidant potential (11.78 µg/mL by DPPH and 140.40 mmol Sulf Fer/g by FRAP) and antimicrobial activity with inhibition for Staphylococcus aureus, Listeria innocua, Salmonella enterica, Escherichia coli and Aspergillus flavus. However, it showed toxicity against brine shrimp (Artemia Salina) (LD50 of 66.26 μg/mL). The 2,5-dihydroxybenzoic acid was indicated as the main compound responsible for the toxicity of ExCb. After treatment in an oven at 110 °C for 15 min, the toxicity of ExCb was reduced by over 7 times, the compound 2,5-dihydroxybenzoic acid was not identified, and still maintained the phenolic compounds content of 94.35% and antioxidant activity compared to the control (without thermal treatment). The application of absorbent containing 50 mg/mL of ExCb added to the packaging maintained the quality and prevented the lipid oxidation of lamb ribs during 10 days of refrigerated storage.

Optimizing the use of spineless cactus in the finishing diet of lambs: physicochemical properties and sensory characteristics of meat

BACKGROUND

The use of spineless cactus in finishing diets for lambs improves the carcass quality. However, data about its influence on meat traits is very scarce. The effects of spineless cactus inclusion in the finishing diet of lambs at four levels (0, 150, 300 and 450 g kg^-1 of dry matter, DM) in replacement of Tifton hay on the physicochemical and sensory properties of meat were studied.

RESULTS

The spineless cactus modified the chemical composition increasing the protein (P < 0.001) and the fat (P < 0.01) contents of meat, presenting the greatest values in lambs fed diets with 150 and 300 g kg^-1 (DM) replacing levels, respectively. However, the spineless cactus did not influence the growth performance from 23.7 to 37.3 kg of body weight (on average). In addition, colour parameters of the meat were not affected by the inclusion of spineless cactus in the finishing diet of lambs, resulting in mean values of 37.55, 14.96 and 8.49 for lightness, redness and yellowness, respectively. There were no statistical differences among treatments for cooking loss and shear force, with mean values of 34.8% and 14.8 N, respectively. Finally, the sensorial properties were not affected by the inclusion of spineless cactus in the finishing diet of lambs.

CONCLUSION

Spineless cactus could be included up to the level of 300 g kg^-1 DM in the finishing diets of lambs to increase the fat content of meat without compromising its sensorial properties. However, further studies about the fatty acid composition of meat from lambs fed diets containing spineless cactus are necessary. © 2019 Society of Chemical Industry.

Physicochemical and sensory characteristics of yoghurts made from goat and cow milk

Substituting goats' milk for cows' milk could improve the quality of dairy products, because it adds new sensorial characteristics. The aim of this study was to develop a type of yoghurt using goats' milk (25, 50, 75 and 100%) in place of cows' milk and to compare their characteristics. Physicochemical, microbiological and sensory characteristics were evaluated using a nine-point hedonic scale and purchase intention test. The data obtained in the physicochemical analysis were submitted to regression analysis and the sensory results were evaluated through analysis of variance. Among the physicochemical characteristics of the yoghurts, variation (P < 0.05) of ash, acidity and lactose was observed. Tasters in the sensory analysis indicated that yoghurts up to 50% of goats' milk received favorable averages; with lower scores for higher goats' milk concentrations (75% and 100%). No difference was reported in acidity. Replacing cows' milk with goats' milk in yoghurt preparation promotes variations in the physicochemical characteristics for ash, acidity and lactose. However, it does not cause alterations in the sensory attributes (50% goat milk) and therefore could be considered as an alternative for the production of dairy products. © 2016 Japanese Society of Animal Science.