Evolution of VOC and Sensory Characteristics of Stracciatella Cheese as Affected by Different Preservatives

Abstract

Undesired volatile organic compounds (VOCs) can negatively affect the flavor of fresh food products; especially those characterized by a mild and delicate aroma. Finding connections between chemical and sensory analyses is a useful way to better understand the arising of off-flavors. A study was conducted on stracciatella; a traditional Italian cream cheese that is emerging on international markets. Samples were prepared by adding two different preservatives (alone or combined): sorbic acid and an olive leaf extract. Their influence on flavor preservation during refrigerated storage was investigated by chemical, microbiological and sensory analyses. A strong change of the VOC profile was ascertained after 8 days in the control cheese and in the sample added with leaf extract alone. The samples containing sorbic acid, alone or in combination with leaf extract, gave the best chemical and sensory results, demonstrating a significant shelf-life extension. In particular, these samples had lower concentrations of undesired metabolites, such as organic acids and volatiles responsible for off-flavor, and received better scores for odor and taste. Ex and Ex-So samples had significantly higher antioxidant activity than Ctr and So throughout the entire storage period, and the color parameter shows no differences among samples taken on the same day. The use of the olive leaf extract, at the concentration tested, seemed to be interesting only in the presence of sorbic acid due to possible synergic effect that mainly acted against Enterobacteriaceae.

Keywords: cheese storage; natural preservatives; sensory characteristics; stracciatella cheese; volatile organic compounds.

Figure 1

Total volatile compounds in stracciatella cheese during storage at 1 (T1), 4 (T4), 8 (T8), 12 (T12) and 16 (T16) days. Different letters above the lines indicate statistically different values (p < 0.05).

Figure 2

Quantitative descriptive analysis (QDA) of stracciatella odor (A) and taste perceptions (B). * = statistically different values (p < 0.05). Sampling time is the same as Figure 1.

Figure 3

Generalized Procrustes analysis (GPA) of the dataset of the odor sensory analysis.

Figure 4

Antioxidant activity evaluation by means of ABTS-TEAC (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)/Trolox^®-Equivalent Antioxidant Capacity) (A) and oxidative stability measurement by RapidOxy (B). Sampling time is the same as Figure 1. Different letters at each sample indicate statistically different values (p < 0.05). Abbreviations: IT, Induction time.

Figure 4

Antioxidant activity evaluation by means of ABTS-TEAC (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)/Trolox^®-Equivalent Antioxidant Capacity) (A) and oxidative stability measurement by RapidOxy (B). Sampling time is the same as Figure 1. Different letters at each sample indicate statistically different values (p < 0.05). Abbreviations: IT, Induction time.

Figure 5

Trend of organic acids in stracciatella cheese during storage. Sampling time is the same as Figure 1. Different letters at each sample time for each acid indicate statistically different values (p < 0.05).

Figure 6

Cell numbers (log CFU g⁻¹, average values of 3 triplicates ± SD) of mesophilic aerobic microorganisms, presumptive mesophilic lactobacilli, mesophilic cocci and enterococci (A), Pseudomonas spp., Enterobacteriaceae and yeasts (B) in stracciatella samples. Ctr = control; Ex = added with olive leaf extract; So = added with sorbic acid; Ex-So = added with both sorbic acid and olive leaf extract. Sampling time is the same as Figure 1. Different letters for each microbial group indicate significant differences at p < 0.05.