Environmental profiles of the encapsulation process of Lactiplantibacillus plantarum CIDCA 83114 in pectin extracts are shown in Fig. 2 for two scenarios: CHE (A) and TS (B) extractions. The percentage contribution of each stage in the process to the total impact revealed that grapefruit peel preparation and pectin hydrolysates were the hotspots of both scenarios, in addition to pectin extraction when CHE is used (Fig. 2a). Grapefruit peel preparation contributed mainly to HTPnce with 64.9% and 65.4% in Scenario 1 and Scenario 2, respectively, and 62% to ODP and WDP in both scenarios. Pectin hydrolysates process mainly contributed to MFRP 46.4% and 48.5% in Scenario 1and Scenario 2, respectively. These contributions are related to the water consumption, organic and chemical waste generated by these processes (Fig. 1). In Scenario 1, pectin extraction by CHE contributed particularly to MRFP (5.68%), CCP (3.10%) and HTPce (2.65%), influenced by the use of time and equipment. In Scenario 2, using TS, all the impact categories contributed less than 1.5%.
Table 3 shows the raw values of the impact categories for Scenarios 1 and 2 and the percentage relation between them. Figure 3 represents the relative percentage normalized values of each impact category for both scenarios. According to the results presented in Table 3, Scenario 1 had the major environmental impact in all impact categories as positive values, except in IRP E. However, the total contribution, calculated in millipoints, showed similar values in both scenarios (CHE = 19.1 and TS = 18.9 mPt).
Figure 3 presents the comparative profile of the environmental impact of the encapsulation process of Lactiplantibacillus plantarum CIDCA 83114 using two pectin extracts methods. The principal impact categories affected were acidification (AP), climate change (CCP), human toxicity cancer effects (HTPce), ionizing radiation HH (IRP HH), photochemical ozone formation (POP) and water resource depletion (WDP). The weighted results of the five principal impact categories were expressed in mPt for both scenarios (Fig. 4). The consumption of electricity during the production of deionized water and the fuel consumption for electricity production are associated with higher CO2 emissions into the atmosphere, as well as increased emissions of nitrogen and sulfur oxides, leading to climate change and acidification impacts, respectively (Marzeddu et al., 2021). Consequently, volatile organic compounds (VOCs) were released, increasing the POP impact (Alisha, et al., 2019) which is correlated with human health impacts (Shajed & Jolliet, 2019). Beccali et al (2009) reported energy consumption as a hotspot in the eco-profiles of six citrus-based products in Italy, related to CO2 emissions and water consumption. Deionized water and electricity consumption were mainly responsible for the environmental impact of Scenario 1 and Scenario 2, as shown in the Sankey diagram, where the thick lines represent the highest impact flux. (Fig. 1S. 2S, 3S).
Figure 5 shows the relative categories results of both scenarios. For each impact categories, the maximum result is set to 100%, corresponding to Scenario 1 (red) and the results of the Scenario 2 (blue) are displayed in relation to this result. As mentioned above, the environmental impact of Scenario 1 is higher than that of Scenario 2, but the differences do not exceed 6%. However, CHE (Scenario 1) showed a better yield (4.1 ± 1.7%) than TS (Scenario 2) (1.5 ± 0.4%), corresponding to the galacturonic acid concentration, which was higher for CHE (786.4 ± 58.2 g/kg) than for TS (605.9 ± 91.8 g/kg) (La Cava et al., 2018). In relation to antioxidant activity (Table 4), pectin extraction by CHE had the best performance. This suggests that the extraction method strongly determines the antioxidant capacity of the samples (Bozinou et al., 2019). In this regard, it has been reported that the acoustic cavitation generated during ultrasound treatment may lead to the production of free radicals, thus explaining the lower antioxidant capacity of TS extracts (Piyasena, Mohareb, & McKellar, 2003).
Table 3. Impact assessment values for 1 kg of protected/dry-encapsulated bacteria in pectin
extracts obtained by conventional heating (Scenario 1) or thermosonication (Scenario 2)
and relative environmental difference between both scenarios.
Impact categories
|
Scenario 1
|
Scenario 2
|
Scenario 1/Scenario 2 (%)
|
AP
|
1.2
|
1.1
|
0.323
|
CCP
|
449.6
|
439.0
|
2.365
|
FETP
|
15.9
|
15.6
|
2.057
|
FEP
|
5.3×10-4
|
5.3×10-4
|
0.101
|
HTPce
|
1.2×10-6
|
1.2×10-6
|
2.018
|
HTPnce
|
9.2×10-6
|
9.1×10-6
|
0.776
|
IRP E
|
3.2×10-4
|
3.2×10-4
|
-0.194
|
IRP HH
|
32.5
|
32.5
|
0.161
|
LUP
|
0.0
|
0.0
|
|
MEP
|
0.3
|
0.3
|
0.501
|
MFRP
|
5.2×10-5
|
5.0×10-5
|
4.390
|
ODP
|
2.7×10-5
|
2.7×10-5
|
0.119
|
PMP
|
0.1
|
0.1
|
0.191
|
POP
|
0.7
|
0.7
|
0.576
|
TEP
|
2.6
|
2.6
|
0.592
|
WDP
|
5.2
|
5.2
|
0.004
|
Differences in the various components of LCA studies (such as functional units, system boundaries, laboratory or industrial scale and impact assessment methods) will be considered for comparing the presented results with other studies. However, several studies show differences between traditional extraction methods and green ones, with the latter being more efficient and environmentally friendly (García-García et al., 2019; Pappas et al., 2023). In agreement with the results of this work, Wang et al. (2015) reported that ultrasound-assisted heating extraction was an efficient and economical method to obtain higher pectin yields at lower temperatures and shorter extraction times than CHE from grapefruit peel.
Despite a similar environmental impact profile, the energy and time consumption in Scenario 1 were higher than that in Scenario 2, so this approach should be carefully managed when making decisions. Considering that the yield of pectin in Scenario 1 was more than double that of Scenario 2, a life cycle cost analysis should be carried out, also taking into account evaluations on an industrial scale (note that this work was carried out on a laboratory scale). Moreover, specific limitation in terms of collecting local and good quality inventory data is a major challenge.