Effect of a Multifunctional Biosurfactant Extract Obtained from Corn Steep Liquor on Orange and Apple Juices

Abstract

Biosurfactant extracts are multifunctional ingredients composed of natural polymers that can be used in the food industry as stabilizing and antimicrobial agents, although their inclusion in food matrices has been scarcely explored. In this work, a biosurfactant extract, with antimicrobial properties, obtained from a fermented stream of the corn wet-milling industry was introduced into an apple and orange juice matrix to evaluate the changes produced in the sugar consumption, pH, and biomass formation at different temperatures (4–36 °C) and storage time (1–7 days). It was observed that the addition of biosurfactant extract reduced the hydrolysis rate of polymeric sugars, decreasing the concentration of soluble sugars from 85.4 g/L to 49.0 g/L in apple juice after 7 days at 20 °C in the absence and presence of biosurfactant extract, respectively. In general, soluble sugars increased in juices for 5–6 days and after those sugars decreased at different rates depending on the temperature of storage. Differences in sugar solubilization and degradation were more significant in apple juice than in orange juice at 20 °C and 7 days of storage, achieving for orange juice values of 101 and 102 g/L in the absence and presence of biosurfactant extract, respectively. Biomass growth was almost unaffected by the biosurfactant extract concentration and the optimal conditions for biomass production were detected at intermediated temperatures after 6–7 days of storage for both apple and orange juices, obtaining maximum concentrations of 1.68 g/L and 1.54 g/L for apple juice and orange juice, respectively, in the absence of biosurfactant extract. The pH during storage was kept in the range of 3.35–3.48 for apple juice and of 3.40–3.77 for orange juice.

Effect of a Biosurfactant Extract Obtained from a Corn Kernel Fermented Stream on the Sensory Colour Properties of Apple and Orange Juices

“…In the absence of the biosurfactant extract the L* values ranged from 74.30 to 77.8 (experiments 5, 6, 9, and 10 in Table 3), and these values were decreased to 59.3-63.7 in experiments 3, 4, 7, 8, 11, and 12 in Table 3, corresponding with the presence of biosurfactant at the highest dose or high temperatures (experiments 3, 4). This means that the addition of biosurfactant had a negative effect on the lightness of apple juice, although this effect was less pronounced when the juice was stored at 4 • C. The lower L* values for apple juice containing biosurfactant extract are in consonance with the decrease in polymeric sugar degradation observed in a previous work on presence of biosurfactant extract [14]. In contrast, the other colour parameters evaluated (a*, b*, ∆E*, and C * ab ) were increased when the biosurfactant concentration was increased up to the highest dose (1 g/L) at conservation temperatures close to 36 • C (variables b* and C * ab ) or even for all temperatures studied (variables a* and ∆E*), as can be observed in Figure 2c,e and Figure 2b,d, respectively.…”

“…This decrease in lightness observed at intermediate experimental conditions (Figure 1a) could be attributed to the possible proliferation of microorganisms causing a slight turbidity in the juice and the release of more acidic compounds, which may be associated with a slight decrease in the pH at intermediate operational conditions. In fact, in a previous work it was proved that there was an increase in biomass growth in natural orange juice up to 0.97-1.07 g/L at temperatures of 20 • C in the presence of 0.5 g/L of CSL biosurfactant extract and a slight decrease in pH from 3.77 to 3.40 [14]. Moreover, lactic acid bacteria, which produce lactic acid that decreases the pH of juice, grow in orange juice at temperatures ranging from 5 to 53 • C; the best conditions being between 30 and 45 • C. This fact it is consistent with the lower L* values observed in Figure 1a.…”

“…On the other hand, the biosurfactant extract was obtained from CSL (Companhia Portuguesa de Amidos, S.A. San João da Talha, Portugal), by means of a liquid-liquid extraction with ethyl acetate following the experimental procedure previously described [20]. The biosurfactant extract under evaluation can decrease the surface tension of water up to 39.5 mN/m and possesses a critical micellar concentration (CMC) of 441 mg/L [14].…”

“…Figure 2 shows the surface response plots corresponding to the variation in the five dependent variables studied (y 1 -y 5 ) in response to variations in the concentration of the biosurfactant extract and the temperature for a fixed storage time of 4 days; this being the last variable the least significant in the studied system according Equations ( 9)- (14). Figure 2a shows the influence of the biosurfactant extract on the lightness (L*); a significant decrease in this variable can be observed when the biosurfactant concentration is Figure 2a shows the influence of the biosurfactant extract on the lightness (L*); a significant decrease in this variable can be observed when the biosurfactant concentration is increased to 1 g/L.…”

“…In a previous work [13], the effect of a biosurfactant extract from corn steep liquor (CSL) in the maceration of red wines was proved, and it was observed that the presence of the biosurfactant promotes the extraction of anthocyanins from the skins during the maceration stage, which could be a promising alternative to preserve the colour properties of young red wines, thus opening an interesting potential for biosurfactants in the winemaking processes. In a recent work [14], the influence of a CSL biosurfactant extract on the stability and shelf-life of two fruit juices (pasteurized apple and natural orange) was also evaluated. It was observed that the presence of the biosurfactant mainly affected the pasteurized apple juice by considerably reducing the concentration of soluble sugars and reducing the glycemic index of the juice; these with negligible changes in the pH values, which is a sign of microbial stability.…”