For the traditional culture system (TCS), the mechanical sowing in pressed peat cubes occurred in the local nursery Piovano Farm, Trofarello (44° 59′ 41” N; 7° 44′ 54″ E), Italy. The seedlings were transplanted with their peat cubes in the soil and arranged in a grid, spaced 0.10 m between rows and 0.10 m within rows, covering a total surface of 26 m². The plant density was approximately 1,000 plants per m². The plants were overhead irrigated and fertilized with organic rabbit manure during plant growing. The TCS was managed by the farmer. The harvest of the whole canopy occurred 90 days after sowing. For the soilless culture system (SCS), the manual sowing in a polystyrene 60-cell tray happened in the same local nursery. Each tray (size, 0.153 m²; 60-cell, 44-mm top, and 25-mm lower diameter, respectively) was filled with specific peat-based horticultural medium (“Neuhaus Huminsubstrat N17”; Klasmann-Deilmann, Geeste-Groß Hesepe, Germany), and contained 180 plants with three plants per hole. The trays were moved into the greenhouse after germination in a controlled chamber at 20°C. A total of 72 trays were arranged on a surface of 26 m². Plant density was approximately 1,180 plants per m². During plant growing, the trays were continuously floating in a nutrient solution containing macronutrients (NH₄)₂SO₄ (0.8 mmol L⁻¹), K₂SO₄ (1.0 mmol L⁻¹), KH₂PO₄ (2.0 mmol L⁻¹), Ca(OH)₂ (1.0 mmol L⁻¹), MgSO₄·7H₂O (2.0 mmol L⁻¹), NH₄NO₃ (3.2 mmol L⁻¹), and microelements (Micral® Aicar Spa, Ronco Scrivia, GE, Italy at 0.16 g L⁻¹) with pH range 5.5–6.5. The pH and electrical conductivity of the nutrient solution were checked weekly and kept close to 6.0 and 2,000 μS cm⁻¹, respectively. The harvest of the whole canopy occurred 81 days after sowing.

At harvest, for each culture system and replication, 2 kg of raw material sample was washed with tap water without any chemical sanitizers. The leaf excess water was removed by centrifugation. At the same time, another 2 kg sample was unwashed. Successively, both the washed and unwashed samples were packaged comparing two packages. An 80-g sample was packaged in (1) polypropylene flow pack bag (FPB) (size: 250 mm × 350 mm) with oxygen permeability of 1,330 cm³ m⁻² d⁻¹ (Alvapack s.r.l.; Bologna, Italy); (2) flow pack bag + trays (FPT) (top, 190 mm × 145 mm; bottom, 140 mm × 100 mm; high, 55 mm, respectively) and wrapped with the same polypropylene flow pack. Subsequently, the packaged samples were stored in refrigerators (Medika 600; Fiocchetti Cold Manufacturer, Luzzara, (RE), Italy) at 4°C and 8°C for a 7-day shelf life. Sampling happened at harvest (d0), d1, and d7 of storage. The statistical design was a randomized complete block design (RCBD) with three replications during plant growth and shelf life. The experimental design consisted of 2 culture systems × 2 washing practices × 2 packaging methods × 2 storage temperatures × 3 blocks × 3 sample days = 144 samples during shelf life.

All data were submitted to the analysis of variance (ANOVA) with repeated measurements using a Mixed Model to analyze the trends over time using the Statistical Package for Social Science (SPSS version 16.0, SPSS, Inc., Chicago, IL, USA). When ANOVA was significant, the culture systems, washing practices, packaging methods, and storage temperature effects were tested using the F-test, and the interaction effect between factors was tested using Tukey’s multiple range test.

Chlorophyll a (Chl a), chlorophyll b (Chl b), total chlorophyll (total Chl), and carotenoids were significantly influenced by the interaction between the culture system and washing practice with p-values of 0.042, 0.033, 0.034, and 0.003, respectively (Table 1). The highest pigment content was in unwashed TCS-grown corn salad, and the lowest in washed SCS-grown samples. TCS produces corn salad leaves with higher pigment content than SCS (Figure 1). The washing practice accelerated the pigment decay, which was more significant in production from TCS than from SCS. In washed TCS-grown corn salad, Chl a, Chl b, total Chl, and carotenoids content decreased by 13.9, 9.1, 12.6, and 11.0% compared to unwashed samples, while these parameters only reduced by 5.4, 3.1, 4.9, and 4.4% in washed SCS-grown plants, respectively (Table 1).

The interaction between the culture system and the packaging method significantly influenced pigment retention over time (Table 2), with the culture system having a more significant effect than the packaging method. The highest pigment retention was found in TCS samples packaged with FPB, while the lowest was observed in SCS samples packaged with FPB. In SCS samples, pigments decreased significantly over time regardless of packaging methods: with respect to the initial value at harvest (d0), FPT resulted in a reduction of 28.19% in total Chl and 29.08% in carotenoids, respectively, at the end of storage; and FPB resulted in a decrease of 32.44% in total Chl and 32.55% in carotenoids, respectively. FPT was more effective in preserving pigment content than FPB by the end of storage. However, in TCS samples, pigment changes were inconsistent across packaging methods: FPB caused a slight increase in pigment content, with a rise of 8.17% in total Chl and 10.15% in carotenoid content, respectively. Conversely, FPT led to a decrease of 8.98% in total Chl and 6.77% in carotenoids, respectively, after 7 days of storage. Consequently, the samples from TCS packaged with FPB contained more total Chl (1.641 vs. 1.392 mg g⁻¹ FW) and carotenoid (0.521 vs. 0.443 mg g⁻¹ FW) content than those packaged with FPT at the end of storage.

The green color represented by pigments is a critical sensory quality and determinative parameter for consumers’ selection and purchase of leafy vegetables. The pigments generally tend to reduce after harvest, and the extent of this reduction largely varies depending on species, cultural technology, processing operation, and subsequent storage conditions (Sinkovič et al., 2023). In this study, TCS produced corn salad containing more pigments than SCS, which is in agreement with the results obtained by Siomos et al. (2001), who found higher Chl a, Chl b, and total Chl content in lettuce (Lactuca sativa L.) harvested from soil culture system than those harvested from soilless culture system. This is possibly attributed to the longer growing days of corn salad grown in TCS (90 days) in comparison to plants grown in SCS (81 days), as mature corn salad tends to accumulate more pigments than immature or “young” plants (Sinkovič et al., 2023). Furthermore, the different nutrient supply and growth medium were the primary technical inputs characterizing the two culture systems tested; thus, they could have influenced the synthesis and content of the pigments in corn salad. Washing is a common and critical practice. During fresh-cut product processing soil, pesticide residues, and debris are removed to reduce microbial load (Kenny and O’Beirne, 2009). This practice and the subsequent drying operation are proven to bring mechanical damage to plant tissues. As expected, our data showed that the washing practice accelerated pigment deterioration of corn salad from TCS and SCS. However, the extent of this deterioration was lower (Chl a, 5.4% vs. 13.9%; Chl b, 3.1% vs. 9.1%; total Chl, 4.9% vs. 12.6%; and carotenoids, 4.4% vs. 11.0%) in SCS-grown corn salad than TCS-grown corn salad (Table 1), implying SCS-grown salad had higher ability to withstand the washing practice in term of pigments degradation. Apart from leaching into washing water from cutting wound juice, the pigment reduction was mainly due to the oxidative degradation caused by mechanical damage brought by washing and the subsequent drying phase, which exposed the leaves tissue to ambient air. It is supposed that the smaller size in leaves and canopies from SCS than those from TCS (3.1 vs. 4.1 g/fresh plant) was beneficial to buffer the impact force of washing water and centrifugal basket extrusion pressure, thus reducing potential wounds and alleviating the deterioration of the pigments. However, due to the lack of comparable literature, further investigation is needed to determine the degree of leaf injuries.

Commercially, salad leaves are marketed in flow pack bags or plastic trays wrapped with flow pack film to prevent wilting (Rux et al., 2017). Placing a tray inside the bag as a support not only facilitates consumer selection and handling of the product but also protects it from crushing injuries during transporting, handling, and marketing. In this study, we found that the packaging method considerably impacted pigment preservation; however, this impact was highly dependent on the culture system. For SCS-grown corn salad, the FPT packaging method showed more beneficial pigment preservation than FPB. In contrast, for TCS-grown corn salad, the FPB packing method was more effective than FPT in preserving the pigments. This contrasting result was possibly explained by the fact that the SCS-grown leaves were “young” (81 days of growth period) and hydrated and tender; the tray acted as a protective barrier around the leaves, reducing crushing injuries. While TCS-grown leaves were mature and “old” (90 days of growth period), the protective effect of FPT was less pronounced. In addition, it is important to note that in the current study, all samples were packaged and placed on chambers’ shelves, simulating basic commercial market conditions, without further distribution, delivery, or display. This reduced the risk of compression and collision injuries, which in turn diminished the protective effect of the FPT packaging method.

The PAL was significantly influenced by the interaction between the culture system and washing practice over time (Table 3). The highest increase in PAL activity occurred in the washed SCS-grown corn salad, with a 30% increase from 0.971 μmol cinnamic acid g⁻¹ FW h⁻¹ at harvest to 1.262 μmol cinnamic acid g⁻¹ FW h⁻¹ at the end of shelf life. PAL activity in corn salad from SCS (1.131 μmol cinnamic acid g⁻¹ FW h⁻¹) was 3.8 times higher than that in leaves from TCS (0.296 μmol cinnamic acid g⁻¹ FW h⁻¹) at harvest (Figure 1), and it maintained significantly higher during the whole storage. The washing effect on PAL activity was observed on processing day (day 0), with notable differences between washed and unwashed samples. However, during the shelf life, these differences leveled off and diminished regardless of the culture system. The PAL activity was significantly influenced by the interaction between washing practice, packaging method, and storage temperature over time (Supplementary Table S1). While no clear conclusion could be drawn from this interaction due to a very high standard deviation (SD), this result must be clarified through further studies. When comparing data based only on the washing practice factor, the results showed a tendency for the washing practice to reduce PAL activity (−4.83%) on the processing day, regardless of treatments, and to induce higher PAL activity (+17.43%) in the washed samples compared to the unwashed samples (+10%) at the end of the shelf life. However, these differences were not statistically significant (Supplementary Table S2). This could be explained by the possibility that the washing practice removed the enzyme by removing the cell fluid on the processing day. At the same time, the washing practice and subsequent drying operations inevitably caused mechanical wounds, inducing the PAL activity to increase during the shelf life, as PAL is a wound-induced enzyme (López-Gálvez et al., 1996).

The PPO was significantly influenced by the interaction between the culture system, washing practice, and packaging method over time (Table 4). The highest PPO activity was observed at the end of the shelf life in washed samples from SCS-grown leaves packaged in FPT. The largest increase in PPO activity was observed in the SCS-grown leaves, unwashed, and packaged with FPB, with a nearly 4-fold increase compared to the initial value (Table 4). The PPO increased over time without reaching the peak in all samples. In the SCS-grown leaves, the washing practice increased the PPO activity (3.333 vs. 1.511 U g⁻¹ FW) on the processing day; thereafter, the differences in PPO activity between unwashed and washed samples leveled off during the shelf life. No clear interaction with the package method was observed. However, no significant differences were observed between treatments in the TCS-grown plants. The PPO activity in all samples increased more than 2-fold (2.33–2.67 folds) at the end of the shelf life compared to the initial value. The enzyme activity of POD was significantly influenced by the interaction between the culture system and washing practice (p = 0.002) (Supplementary Table S3), as well as the culture system over time (p < 0.001) (Supplementary Table S4). The POD enzyme activity was 0.273 ∆A_λ min⁻¹ g⁻¹ FW in SCS samples but was not detected in TCS samples. The washing reduced POD activity by 30% in SCS samples (Supplementary Table S3). At the end of the shelf life, POD activity in SCS samples was more than 2-fold compared to the initial value (Supplementary Table S4).

PPO is the key enzyme responsible for plant-based food browning development. It can directly catalyze the oxidation of polyphenols into o-quinones in the presence of oxygen, which subsequently polymerize into browning or/ and black pigments, known as tissue browning (Degl’Innocenti et al., 2007). POD is normally considered an antioxidant enzyme for scavenging free radicals in plants under stress conditions. POD catalyzes the conversion of hydrogen peroxide to water using polyphenols as hydrogen donors, which produces red browning substances (Lee et al., 2021). Consequently, POD is often considered to cooperate with PPO to trigger food quality decay in polyphenol oxidation and browning color development (Shao and Zhang, 2015). Therefore, both enzymes have been evaluated to monitor the quality deterioration of fresh products during postharvest processing and preservation (Jang and Moon, 2011). In this study, PPO and POD displayed irregular behaviors when different treatments were applied. Overall, in comparison to TCS, SCS produces corn salad with lower PPO (1.511 vs. 2.178 U g⁻¹ FW) but higher POD (0.232 ∆A_λ min⁻¹ g⁻¹ FW vs. not detected) at harvest (Figure 1). Such low PPO activity might be associated with higher AA content in leaves from SCS at harvest (Figure 1), as AA possesses strong inhibitory activity against PPO by forming an AA-PPO complex (Li et al., 2022). In addition, the plant maturity of the harvest also affects the PPO activity. Korus (2011) demonstrated that the PPO activity in three varieties of kale increased with the degree of plant maturity: the PPO activity was 19% higher at the 2nd stage (14 weeks growth) and 75% higher in the 3rd stage (18 weeks growth) in comparison to the 1st stage (10 weeks growth). In our study, the lower PPO activity observed in SCS-grown leaves could be attributed to their lower maturity (81 days of growth) than TCS-grown leaves (90 days of growth). The washing practice induced the PPO activity in SCS samples on the processing day (Table 4). A reasonable explanation could be that the washing and subsequent drying operations mechanically destroy the cell integrity of tissue, provoking cell lysis, which is highly related to the increase in PPO enzyme activity (Nogales-Delgado, 2021). During the postharvest phase, the largest increase (3.95-fold) in PPO activity was observed in unwashed SCS samples packaged with FPB (Table 4). Such an increase is likely the result of a synergistic effect of the factors tested. Washing is typically used to remove surface soil, microorganisms, and other contaminants. Unwashed samples may harbor a higher microbial population, which could activate PPO activity, as microorganisms can damage tissue integrity and increase enzyme activity (Nogales-Delgado, 2021). Additionally, modified atmosphere packaging with a high CO₂ concentration has been shown to inhibit PPO activity (Galvis-Sánchez et al., 2006; Nogales-Delgado, 2021). Based on these facts, we speculated that the unwashed samples contained more microbial matter due to the absence of the washing procedure, which may activate the PPO activity. Furthermore, FPB packaging might have resulted in a lower CO₂ concentration due to the larger bag space, which dilutes the headspace gas concentration compared to the smaller size of the tray used in FPT packaging (Supplementary Figure S1). Therefore, the conditions in the unwashed samples packaged with FPB likely favored PPO activation. POD, an antioxidant enzyme, plays an important role in protecting plant cells from oxidative damage caused by reactive oxygen species (ROS)—often produced under stress conditions. The activation of POD helps to mitigate this damage. As described in the “Materials and Methods” section, the SCS system consists of floating the plants in a nutrient solution; the lower temperature and/or greater temperature fluctuation of the nutrient solution in the winter would be an abiotic factor to stress the plant growth. In this context, the higher POD activity in SCS samples could be interpreted as a defensive mechanism triggered by the plant in response to this abiotic stress. In addition, the SCS system allows plant roots to be continuously immersed in a water solution, creating a hypoxic condition in the root zone. This low oxygen condition is another abiotic stress factor the plants can encounter. In response, the plant antioxidant system, including antioxidant enzymes such as POD, is activated and induced to act as a protective antioxidant to improve the plant’s tolerance to stress conditions by scavenging the oxygen-free radical (Liang et al., 2017; Pan et al., 2021). In tomato production, the growing systems of open fields and net houses had a remarkable impact on PPO and POD activity. However, this impact is highly genotype-specific (Lee et al., 2021), illustrating that both cultural systems and species gene background considerably impact PPO and POD activity. Unfortunately, studies on the culture system and postharvest factors affecting PPO and POD activity of leafy greens are very limited; thus, there is no equivalent data to compare. Therefore, further trial is imperative to clarify these enzyme behaviors in different corn salad varieties or other leafy green species before concluding. In addition, the activities in both PPO and POD showed a considerable increase over time regardless of the treatments. However, no browning symptoms were observed for all leaves at the end of storage, indicating corn salad is non-susceptible to tissue browning and still marketable after 7 days of storage in cold conditions.

The culture system significantly influenced the content of the overall total ascorbic acid (TAA), ascorbic acid (AA), and dehydroascorbic acid (DHA). In contrast to pigments, the SCS system allowed to produce corn salad leaves with a higher content of 25.6% TAA (50.47 vs. 40.19 mg 100 g⁻¹ FW), 17.5% AA (24.47 vs. 20.84 mg 100 g⁻¹ FW), and 34.4% DHA (26 vs. 19.36 mg 100 g⁻¹ FW) than TCS system at harvest (Figure 1). These data were consistent with the results reported by Frezza et al. (2005), who found that the AA content in lettuce from the floating system was significantly higher (+72%) than that from greenhouse soil. Furthermore, the plant growth stage at harvest is a major factor determining the compositional quality of leafy vegetables (Skrypnik et al., 2021). The same authors found that lamb lettuce harvested at the short growth stage (52 days after sowing) contained significantly higher levels of AA content than those harvested at the longer growth stage (66 days after harvest sowing). Similarly, the spinach baby leaves exhibited higher AA and TAA when harvested at a younger stage (17–18 days after sowing) than those harvested at an older stage (23–24 days and 29–30 days) (Bergquist et al., 2006). In our study, corn salad from SCS had a shorter growth period (81 days) than that from TCS (90 days) at harvest; this reduced plant growth stage could be responsible for the higher TAA and AA content observed in SCS-grown leaves. As regards the variations of these parameters over time, TAA was influenced only by storage time, with 27.3% at the end of shelf life regardless of treatments (data not shown). DHA was significantly influenced by the interaction between cultural systems and packaging methods over time. In SCS-grown corn salad, DHA significantly increased over time, and this change was more gradual and less with FPT than with the FPB package. In TCS-grown corn salad, no differences resulted between the packaging methods, and at the end of shelf life the DHA increase values were similar (Table 5).

As known, AA, the reduced form of vitamin C, is prone to deterioration and oxidizes into DHA, the first oxidation product of AA, in the presence of molecular oxygen (Lee and Kader, 2000). The opposite direction of this reaction, which would regenerate AA, is not thermodynamically the most favored (Degl’Innocenti et al., 2007). Thus, AA tends to decrease, and meanwhile, DHA increases during postharvest storage of fresh fruit and vegetables. In our study, less DHA generation (28.89 vs. 36.37 mg 100 g⁻¹ FW) was found in the SCS-grown produce packaged with FPT than FPB, illustrating less AA deterioration occurred in FPT. However, no significant change in AA content was observed. This could be attributed to the tray in PBT, which acted as a protective holder and oxygen barrier, reducing mechanical injuries and limiting oxygen availability, thereby preventing the oxidation of AA into DHA. Additionally, as shown in Supplementary Figure S1, compared to the larger size of the bag in FPB, the smaller size of the tray in FPT allowed for the creation of faster and intensive modified atmosphere conditions, characterized by high CO₂ and low O₂ levels resulting from leaf respiration. This low O₂ content in the FPT alleviated the oxidation of AA to DHA. However, FPT showed no impact on DHA generation for leaves from TCS, which was possibly associated with the reduced movements and collisions of products during the whole storage period. In our study, although the materials were processed and stored to simulate commercial conditions, the absence of shipping, distribution, and marketing processes reduced the potential for friction injuries, possibly concealing the protective function of packaging accessories such as trays. However, in a real supply chain, the processors generally are not sellers, so the packaged produce has to be distributed to different retailers after packaging, in some cases via wholesales, during which the produce is supposed to suffer from injuries of compression or collision. Storage at low temperatures is highly recommended for leafy vegetable to preserve their visual quality and nutritional content. Storage of spinach baby leaves at 2°C reduced AA content less than storage at 10°C (Bergquist et al., 2006). In our study, unexpectedly, the storage temperature had no significant effect on AA. This may be attributed to the small temperature difference between the tested temperature (8°C vs. 4°C). Usually, the degradation rate of unprotected AA doubles with every 10°C increase in temperature (Pavlovska and Tanevska, 2013). Furthermore, unlike in the commercial supply chain, the absence of temperature fluctuation during the entire storage period was favorable for AA preservation. Therefore, further studies should focus on the complete commercial conditions simulation to clear this issue.

Culture systems only affected TP content, of which SCS-grown corn salad had more than 57.1% TP than that grown in TCS at harvest (0.77 vs. 0.49-mg gallic acid g⁻¹ FW) (Figure 1). TPs are a large group of plant secondary metabolites that play an important role in plant-derived food quality, representing quality characteristics and health-promoting properties (Hernández et al., 2021). In plant tissue, TP biosynthesis originates from trans-cinnamic acid that is formed via PAL catalyzing the non-oxidative deamination of L-phenylalanine; TP oxidative degradation via PPO that catalyzes/oxidizes TP to quinones in the presence of molecular oxygen (Tomás-Barberán and Espín, 2001). Thus, the actual assayed concentrations of TPs in plant tissue depend on the balance between the TP synthesis rate and their oxidation rate (Zhan et al., 2020). In this study, the differences in TP concentration from SCS and TCS followed this pattern, which was consistent with the trend of their respective synthetic and oxidative enzyme activity. That is, in comparison to TCS-grown leaves, SCS-grown corn salad had significantly higher PAL activity (1.14 vs. 0.34 μmol cinnamic acid g⁻¹ FW h⁻¹) and lower PPO activity (1.51 vs. 2.18 Ug⁻¹ FW) (Figure 1). this implied that the TP biosynthesis rate was faster while its oxidization rate was slower, consequently leading to more accumulation of de novo TP. Actually, a positive correlation (R = 0.785, p < 0.001) between PAL and TP (Figure 2) further confirmed PAL’s critical responsibility in TP accumulation. Furthermore, the higher AA level in SCS-grown leaves might be partly responsible for the higher level of TP because AA could not only directly reduce quinones back to phenols but also inhibit PPO action and limit the oxygen availability, thus indirectly retard TP oxidation (Degl’Innocenti et al., 2007; Li et al., 2022). This explanation was supported by the positive relationship between AA and TP (R = 0.382, p < 0.001) (Figure 2). Similar trends were also reported by Reyes et al. (2006), who found that vegetables (e.g., white and red cabbage) with higher AA levels had a greater soluble phenols content. Conversely, vegetables (e.g., lettuce and celery) with lower AA levels had a lower soluble phenols content.

The AC was significantly influenced by both cultural systems over time (p < 0.001) and washing practices over time (p = 0.039) (Table 6). AC values were higher (+67%) in leaves from SCS than in TCS at harvest, and they increased by 66.1% at the end of shelf life without reaching the peak. Comparatively, in leaves from TCS, AC values were low at harvest, increased to a peak on the first day of storage (d1), and then decreased thereafter (Table 6). The AC in leafy vegetables is mainly derived from phytochemicals, including TP compounds, vitamins, and flavonoids (Rico et al., 2007). The present study also showed that SCS produced corn salad with significantly higher AC values than TCS at harvest and shelf life. Such a high level of AC was attributed to its high level of TAA, AA, and TP content, as the extremely significant correlations between AC and these bioactive substances were established regardless of treatments (Figure 2), indicating TAA, AA, DHA, and TP were the main contributors to AC value in corn salad. These findings were in agreement with those of Martínez-Sánchez et al. (2008), who reported the strong correlations between AC values and content of TP and vitamin C in baby leaves of Brassicaceae species, such as wild rocket and salad rocket, whose baby leaves are suggested to be good dietary sources of antioxidants with a variety of important bioactive compounds. Washing operation significantly increased AC values (+16.5%) only at processing day (d0). During the subsequent storage days, in both washed and unwashed samples, AC increased with similar dimensions and reached the same level (15.2 vs. 15.8 μmol Fe²⁺ g⁻¹ FW) at the end of the shelf life (Table 6). This transient increase in AC values after washing could have been elicited by the mechanical wounds brought by the washing and consequent drying practices because wound, as an abiotic factor, could induce the increase in AC values of fresh-cut produce such as lettuce (Kang and Saltveit, 2002) and lotus root slices (Hu et al., 2014). However, inconsistent data was also reported by Kenny and O’Beirne (2009), who found no significant effect of washing practices (tap rinsed, water-dipped, chlorine dipped) on AC of ready-to-use iceberg lettuce during 8 days of storage.

The minimally processed corn salad fresh weight loss was significantly influenced by the culture system (p < 0.001), package method (p = 0.003), and storage temperature (p < 0.001), respectively (Supplementary Tables S5–S7). However, despite these significant effects, the overall fresh weight loss was minimal in all samples. The highest fresh weight loss observed in TCS-grown leaves was only 0.38% (Supplementary Table S5), far below the 4–5% threshold that renders the leafy vegetable texture unacceptable (Nunes and Emond, 2007). Thus, all corn salad leaves were fresh and marketable after 7 days of storage. This result was in agreement with our previous finding, where corn salad grown in SCS lasted 8 days shelf life in the cool chamber at 4°C (Fontana and Nicola, 2009). Similar results were also reported in our recent studies of other leafy baby leaves, such as lettuce (Pignata et al., 2020), spinach (Zhan et al., 2020), and lettuce and rocket salad (Zhan et al., 2022), all of which were usually turgid and fresh after 7 days of storage at cool condition.