Biopreservative Effect of the Tunisian Halophyte Lobularia maritima Flavonoid Fraction, Used Alone and in Combination with Linalool in Stored Minced Beef Meat

Abstract

In the present study, Lobularia maritima (Lm) flavonoid extract (LmFV) was characterized by HPLC analyses and five compounds were detected. Further, to describe the chemical content of the matrix, GC-MS analyses after silylation were performed; the obtained results showed the presence of a large number of components belonging to several chemical classes, mostly sugar alcohols, sugars, fatty acids, and terpenes. Firstly, the antibacterial activities of this fraction and linalool (Lin) were evaluated against eight foodborne pathogenic strains with MIC values between 2.3 and 5.8 mg/mL and 0.23 and 0.7 mg/mL, respectively. Then, the antioxidant activity of both was evaluated by the DPPH antiradical test and the phosphomolybdenum test. Furthermore, the biopreservative effect of LmFV alone and in combination with Lin on minced beef stored at 4 °C for 14 days was evaluated using microbiological and physiochemical tests. LmFV at 4.6% alone significantly reduced microbial spoilage in ground meat (p < 0.05). The combination of LmFV (4.6%) and Lin (0.46%) was more effective than LmFV alone in inhibiting bacterial contamination, reducing TBARS values and the risk of bacterial contamination, and reducing the accumulation of Met myoglobin (MetMb). This combination, therefore, extends the shelf life of the product by about 10 days. Based on these microbiological results and physicochemical parameters, it can be stated that the addition of Lin potentiates the flavonoid fraction of L. maritima more strongly against the deterioration of meat quality by significantly improving its biopreservative effect as a natural conservative.

Keywords: antioxidant activity; chemical composition; flavonoid extract; linalool; microbial spoilage; minced beef meat; multivariate analysis; synergistic effect.

Figure 1

Chromatograms of flavonoid standards: (A) standard chromatograms; (B) flavonoid constituents of L. maritima.

Figure 2

GC-FID chromatogram of L. maritima silylated ethanolic extract.

Figure 3

Effect of BHT, 1 LmFV, 2 LmFV, and 2 LmFV+Lin on the microbial load of APC (a) and PTC (b) (log CFU/g) of raw minced meat samples stored at 4 °C for 14 days; means ± SEMs (n = 3). Values with a different letter (a–c) for the same storage day are significantly different (p < 0.05). Values with a different letter (A–C) for the same concentration are significantly different.

Figure 4

TBARS (mg MDA-eq/Kg) values for raw minced beef stored at 4 °C for 14 days; means ± SEMs (n = 3). Values with a different letter (a–c) for the same storage day are significantly different (p < 0.05). Values with a different letter (A,B) for the same concentration are significantly different.

Figure 5

Effect of BHT, 1 LmFV, 2 LmFV, and 2 LmFV+Lin on (a) MetMb (%) of raw minced beef stored at 4 °C for 14 days; means ± SEMs (n = 3). Values with a different letter (a–e) for the same storage day are significantly different (p < 0.05). Values with a different letter (A–E) for the same concentration are significantly different.

Figure 6

Loading plots of the two principal components (F1, F2) based on all samples (n = 25) (a) and on physicochemical and microbial growth of meat samples over 14 days of storage (b).

Figure 7

Agglomerative hierarchical cluster analysis (HCA) (a) and profile of classes (b) of physicochemical characteristics and microbial counts of different samples at each storage time: 0, 3, 7, and 14 days.

Figure 8

Heat maps of physicochemical properties and microbial growth for different samples during the refrigerated storage.