Postharvest Biology and Technology 195 (2023) 112113 Contents lists available at ScienceDirect Postharvest Biology and Technology journal homepage: www.elsevier.com/locate/postharvbio Potential application of pre-harvest LED interlighting to improve tomato quality and storability E. Appolloni a, G. Pennisi a, *, I. Paucek a, A. Cellini a, A. Crepaldi b, F. Spinelli a, G. Gianquinto a, X. Gabarrell c, F. Orsini a a Alma Mater Studiorum – Università di Bologna, DISTAL – Department of Agricultural and Food Sciences, Bologna, Italy b Flytech srl, Via dell’Artigianato, 65, 32016 Alpago, Belluno, Italy c Universitat Autònoma de Barcelona, Institut de Ciència i Tecnologia Ambientals (ICTA-UAB), MdM Unit of Excellence CEX2019-000940-M; Chemical, Biological and Environmental Engineering Department, Barcelona, Spain A R T I C L E I N F O A B S T R A C T Keywords: Growing conditions and agronomical inputs play a key role in determining fruit qualitative and nutraceutical Supplemental lighting traits at harvest and post-harvest. The hereby presented research investigated the effects of pre-harvest sup­ Light emitting diode plemental LED interlighting on post-harvest quality of hydroponically grown tomatoes (Solanum lycopersicum Post-harvest “Siranzo”). Three LED treatments, applied for 16 h d-1 (h 8.00–00.00), were added to natural sunlight and Solanum lycopersicum Food waste consisted of Red and Blue (RB), Red and Blue + Far-Red (FR), and Red and Blue + Far-Red at the end-of-day for 30 min (EOD), with an intensity of 180 µmol m-2 s-1 for Red and Blue, plus 44 µmol m-2 s-1 for Far-Red. A control treatment (CK), where plants were grown only with sunlight, was also considered. Fruits at red stage were selected and placed in a storage room at 13 ◦ C in darkness. Fruit quality assessment was performed at harvest time and after one week of storage. RB and FR increased fruit firmness compared to CK, opening possible benefits toward reducing fruit losses during post-harvest handling. RB treated fruits also maintained a higher content of lycopene and β-carotene after the first week of storage. The study demonstrates that supplementary LED inter­ lighting during greenhouse tomato cultivation may enhance storability and help preserve fruit nutritional properties during post-harvest. 1. Introduction and fungal development (Mata et al., 2019). Pre-harvest conditions and agricultural inputs are also crucial in Post-harvest management is essential in maintaining tomato quality, determining fruit quality at harvest and post-harvest ripening (Isaac ensuring long-term shelf-life, and reducing food waste from unsold and et al., 2015). For example, fertilizers may help prevent disease devel­ perishing products. Indeed, post-harvest losses of tomatoes can reach opment (e.g., calcium) (Passam et al., 2007) or reduce ripening and 25–40% of production (Khan and Jan, 2007), with economic conse­ color formation (e.g., nitrogen); flowers and fruit pruning help obtain an quences relapsing on farmers, the processing industry and traders appropriate source/sink ratio and allow to increase fruit weight and dry (Kader et al., 1992). Cold storage, high carbon dioxide atmosphere, matter content (Hanna, 2009); and correct irrigation management can calcium chloride application and relative humidity control are some increase sugar concentration in fruit (Mitchell et al., 1991). The matu­ methods applied to reduce tomato’s respiratory metabolisms and rity stage at which the fruit is harvested is another important pre-harvest consequent food losses during post-harvest handling (Toor and Savage, factor that can influence post-harvest preservation. In particular, har­ 2006; Isaac et al., 2015). In particular, a storage temperature between vesting tomatoes at mature green stage can ensure a longer product 10 and 15 ◦ C is the most applied for post-harvest preservation (Mata shelf-life (Moneruzzaman et al., 2009), thanks to a lower sugar content et al., 2019), being this the ideal temperature to ensure the long-term that makes the fruit less vulnerable to mechanical damage (Toivonen, preservation of the fruit without impairing tomato flavor properties 2007). However, early harvests were also shown to reduce the nutri­ (Maul et al., 2000). Furthermore, storage temperatures lower than 13 ◦ C tional and sensorial properties of the product (Balibrea et al., 2006; Isaac can determine chilling injury, affecting tomato texture, surface pitting et al., 2015), with negative consequences on consumers’ perception and * Corresponding author. E-mail address: giuseppina.pennisi@unibo.it (G. Pennisi). https://doi.org/10.1016/j.postharvbio.2022.112113 Received 16 July 2022; Received in revised form 14 September 2022; Accepted 14 September 2022 Available online 28 September 2022 0925-5214/© 2022 Published by Elsevier B.V. E. Appolloni et al. Postharvest Biology and Technology 195 (2023) 112113 nutritional value. Therefore, harvesting at mature-green stage can be 3) RB treatment with an addition of 44 µmol m− 2 s− 1 of Far-Red, advisable in case of product transportation at long distances while applied only for 30 min right after the 16 h d-1 of RB treatment (end- harvesting at red ripen stage is the best option for local consumption of-day) (namely EOD). (Moneruzzaman et al., 2009; Isaac et al., 2015). Peak wavelengths of emitted spectrum are reported in Fig. S1. Light is a key factor in determining fruit quality being the main Control plants (CK) grown under natural light were also considered. responsible for photosynthetic activity. In recent years, the development Lighting treatments were applied only for the final phase of the pro­ of highly efficient and low-cost light-emitting diodes (LEDs) has allowed ductive farm cycle, from August until November 2020. A randomized the adoption of this technology for protected crop production (Paradiso block design was used with three blocks containing 7 plants per treat­ and Proietti, 2021), fostering the study of how light manipulation may ment (21 plants per treatment in total) (Fig. S2). affect plant performances and fruit quality, particularly in tomatoes (Appolloni et al., 2021). Furthermore, LED light has also been applied to 2.2. Post-harvest preservation harvested tomatoes during storage to enhance berry quality and storage (Cozmuta et al., 2016; Ngcobo et al., 2021). Chlorophylls absorption Trusses at equal development stage were harvested from each plant. peaks correspond to the Blue and Red spectral regions, and, therefore, Afterward, fruit at red-mature stage and of the same size were selected several studies focused on the effect of Red and Blue lights on crop yield among the harvested trusses. The fruit’s red-mature ripening level was and quality (Kataoka et al., 2003; Li and Kubota, 2009; Pennisi et al., estimated by using a portable DA-Meter (DA-Meter, SINTELEIA srl, 2019, 2020). Blue light strongly affects leaf expansion and stomatal Bologna, Italy) (Rahman et al., 2019). DA-Meter is a portable device opening and frequently promotes the development of a more efficient based on visible/Near Infra-Red (vis/NIR) spectroscopy developed to photosynthetic apparatus than Red light (Savvides et al., 2012; Miao non-destructively assess fruit maturity (Farneti et al., 2015). Tomato et al., 2016). Red light promotes seed germination and growth and may fruits were selected for a uniform maturation red-ripe stage corre­ enhance chlorophyll accumulation (Fan et al., 2013; Tiansawat and sponding to a DA-index (IAD) between 1.50 and 1.90. After the selection, Dalling, 2013). In addition, the Red:Far-Red ratio controls plant archi­ tomatoes were immediately washed with sodium hypochlorite and tecture, germination and flowering, although with different responses stored in the dark at 13 ◦ C, with 80% relative humidity, for 7 days. The depending on plant species and growing conditions (Demotes-Mainard duration of storage was established based on the standard applied by the et al., 2016). To the best of our knowledge, only minimal research has commercial greenhouse that furnished the tomatoes. investigated the effects of LED light applied during cultivation on the post-harvest quality of tomato fruit (Affandi et al., 2020, 2021). How­ 2.3. Weight loss and hardness ever, supplemental LED light application may be an interesting pre-harvest factor influencing post-harvest quality to be evaluated, Weight loss was calculated on 6 fruits per treatment per block as the given the activation of photoreceptor responses affecting plant meta­ difference between the weight of the fruit at the beginning of storage bolism. Accordingly, the present research aims to evaluate the effects of (T0) and their final weight after 7 d of storage (T7) divided by the T0. To pre-harvest supplemental LED light on post-harvest quality of normalize data, weight loss values were expressed as % of the initial greenhouse-grown tomatoes, considering commercial storage standards. value. On the same fruits in the same days, fruit hardness was evaluated using a Durofel device (Giraud Technologies, Cavaillon, France) (Plan­ 2. Materials and methods ton, 1991), fitted with a 0.10 cm2 probe, on four opposite sides of the equatorial diameter of each fruit per time point. The instrument 2.1. Pre-harvest growing conditions non-destructively measured the elasticity of fruit exocarp, expressing it in a Durofel Index ranging from 0 to 100. Tomato plants (Solanum lycopersicum L. ‘Siranzo’ Rijk Zwaan, The Netherlands) were cultivated in a commercial greenhouse located at 2.4. Color determination Mezzolara di Budrio, Bologna, Italy (44◦ 34’49” N, 11◦ 31’54” E), using a high-wire hydroponic system (Paucek et al., 2020). Seedlings in rock­ Color was evaluated on 6 fruits per treatment per block at T0 and T7 wool cubes were transplanted in rock wool slabs (Grodan Vital, Roer­ on the same fruit by using a CIE Lab color space analysis, where L* mond, Netherlands) on January 13, 2020. Plants were grown with a component represents the lightness from black (0) to white (100), a* two-stem V-system with a planting density of 3.1 stems m-2. The envi­ component is a value ranging from green (− ) to red (+), and b* ronmental conditions (temperature, relative humidity, solar radiation) component is a value ranging blue (− ) to yellow (+). A colorimeter were monitored daily during the entire growing period. A passive (Chroma Meter CR-400, Minolta, Tokyo, Japan) was used to assess the (lateral and top openings) and active (horizontal fan system) ventilation, values. The measures were performed on four opposite sides at the as well as residual hot water flowing in tubes coming from an adjacent equatorial diameter fruit level. Two indexes, HUE angle (h) and Chroma biogas system, were used to maintain the proper climatic conditions (C), were deduced from a* and b* components applying the formulas (Tmax 37 ◦ C - Tmin 11 ◦ C; RHmax 97% – RHmin 36%). A tan-1 (b*/a*)2 and (a*2 + b*2)0.5, respectively (Lopez Camelo and computer-controlled drip-irrigation system managed fertigation, main­ Gomez, 1998). taining the nutrient solution at average pH= 6.0 and 2.6 dS m− 1 average electrical conductivity (EC). The nutritive solution adopted by the 2.5. Destructive measurements for fruit quality evaluation commercial greenhouse is reported in Table S1. The supplemental lighting was provided by a single LED interlighting lamps (Flygrow Destructive measurements were performed on 6 fruits per treatment Interlight, Flytech LED Technology, Belluno, Italy), located at 30 cm of per block, other than those of non-destructive measurements, and distance from the stem, at the height of 1.40 cm from the rock wool slabs included pulp firmness, soluble solids content and titratable acidity throughout the whole growing period. Three different lighting regimes evaluation. Pulp firmness was determined using a fruit texture analyzer were applied: (FTA GÜSS, Strand, South Africa), evaluating the force required to 1) Red (660 nm) and Blue (465 nm) light with a Red:Blue ratio (R:B) penetrate the fruit. The penetration was performed with a cylindrical of 3, a photosynthetic photon flux density (PPFD) of 180 µmol m− 2 s− 1 and flat-end probe of 6 mm of diameter, with a depth equal to 11 mm (measured at 30 cm from the plant) and a photoperiod of 16 h d-1 and a speed of 30 mm s-1. Measurements were performed on four (8.00–00.00) (namely RB);. opposite sides of the equatorial diameter, peeling the fruit before 2) RB treatment with an addition of 44 µmol m− 2 s− 1 of Far-Red light penetration. Soluble solids content was evaluated on each centrifuged (730 nm) during the whole photoperiod (namely FR);. fruit using a digital refractometer model PAL-1 (Atago Co., Ltd., Tokyo, 2 E. Appolloni et al. Postharvest Biology and Technology 195 (2023) 112113 Japan). Titratable acidity was measured with an automatic TitroMatic of mixed solvents added for hexane:acetone:ethanol (2:1:1), V is the (Compact-S titrator, Crison, Modena, Italy), diluting 20 mL of tomato volume of mixed solvents added and 537 (g mol-1) is the molecular juice in 20 mL of distilled water. The titratable acidity was estimated by weights of lycopene and β-carotene. titrating with 0.1 N NaOH until the titration end-point of pH 8.1. 2.8. Statistical analysis 2.6. Total polyphenols and total antioxidant capacity Non-destructive measurements (weight loss, fruit hardness, color) Total polyphenols and total antioxidant capacity were analyzed on 4 were analyzed through a repeated measures one way-ANOVA. tomatoes per treatment per block, other than those of non-destructive Destructive measurements (pulp firmness, soluble solids content and measurements. At T0 and T7, fruit samples were immersed in liquid titratable acidity) and biochemical evaluations were analyzed through a nitrogen and kept at − 80 ◦ C for analysis. Samples of 4 g of homogenized one-way ANOVA, by comparing lighting regimes within the different freeze-dried fruit were placed in tubes and 8 mL of extraction mixture time (T0 and T7). Tukey’s test was used for means comparison. Data (60% methanol, 30% H2O, 10% acetone) were added (Hartmann et al., were analyzed by using SPSS software. 2008). The extraction was carried out by centrifugation at 1677 g for 10 min at 4 ◦ C. The supernatant was collected and used for antioxidant and 3. Results total phenols analysis. Total antioxidant capacity was analyzed using the FRAP (Ferric No differences in weight loss (as % from initial fruit weight) were Reducing Antioxidant Power) method, developed following the method observed between lighting treatments (mean weight loss of 1.8%, described by Benzie and Strain (1999), applying slight modifications. A Table 1). The evaluation of fruit exocarp hardness showed no differences reaction mixture containing acetate buffer (pH 3.6), 300 mM, 2,4,6-Tris among treatments at T0. However, CK fruits were softer after one week (2-pyridyl)-s-triazine (TPTZ) solution (in 40 mM HCl) and 20 mM FeCl3 compared to RB and FR ones (Fig. 1a). The same trends were observed in was prepared in a v:v:v proportion of 10:1:1 and incubated for 2 h in flesh firmness evaluation, although no significant differences were darkness. Then, 1.2 mL of the reaction mixture was added to 20 µL of observed among treatments at both measured times (T0 and T7) supernatant and incubated for 1 h at room temperature in darkness. The (Fig. 1b). antioxidant capacity was referred to a 0–2.5 mM FeSO4 calibration Evaluations of fruit color did not show any difference among treat­ curve. Samples and standards were read at 593 nm with a spectropho­ ments neither at harvest or after 7 days of storage (Table 1). Mean fruit tometer (Biochrom Ltd, Cambridge, England). values at T0 and T7 were respectively 24.1 and 22.3 (a*), 30.7 and 29.4 Total polyphenols were determined using the methodology (b*), 41.8 and 40.6 (L*), 0.91 and 0.92 (h), 39.0 and 36.9 (C). Similarly, described by Waterhouse (2002), applying slight modifications. Briefly, soluble solid content (average value T0: 4.2 and T7: 4%) and titratable 50 µL of the sample extract was added to 800 µL of Folin-Ciocalteu re­ acidity (average value of T0: 4.1 and T7: 3.4 g L-1) were not significantly agent diluted 1:15 (v:v) in H2O. Gallic acid calibration standards up to influenced by lighting treatments (Table 1). 400 µg mL-1 were also included in the test. After an incubation of 5 min, Biochemical analysis showed no differences among treatments in the samples and standards were added with 150 µL of 20% Na2CO3, incu­ case of total phenols content (average value 28.2 and 25.9 mg GA eqs. bated for 1 h at room temperature and then read at 765 nm with a 100 g-1) and antioxidant activity (average values of 0.28 and 0.28 mmol spectrophotometer (Biochrom Ltd, Cambridge, England). Results of total Fe2+ eqs. 100 g-1), at T0 and T7, respectively (Table 1). Instead, carot­ phenols and antioxidant activity were expressed in gallic acid and Fe2+ enoid analysis demonstrated a significantly lower level of lycopene and equivalents, respectively, on a fresh weight basis. β-carotene in fruits grown with natural light only (CK) compared to fruits grown under RB light treatment, after one week of post-harvest storage (Fig. 2a and Fig. 2b). 2.7. Lycopene and β-carotene content 4. Discussion Lycopene and β-carotene contents were evaluated on 4 tomatoes per treatment per block, the same as total polyphenols and total antioxidant Weight loss is one of the main problems of quality reduction in capacity measurement, using the methodology described by Anthon and horticultural products during post-harvest (Nassarawa et al., 2021). The Barrett (2006), applying slight modifications. An extraction solution was reasons for weight loss of tomatoes during storage can be attributed to prepared by mixing hexane, acetone and ethanol in a v:v:v proportion of environmental conditions, such as fruit’s dehydration (Fagundes et al., 2:1:1, plus 0.5 g L-1 of butylated hydroxytoluene. Briefly, 0.5 g of ho­ 2015), as well as to normal cellular metabolic processes such as tran­ mogenized frozen sample, including exocarp and mesocarp, were mixed spiration and respiration (Abiso et al., 2015). In the present research, with 10 mL of extraction solution. The material was left in darkness for tomatoes grown under different LED light treatments (RB, FR and EOD) 30 min and then centrifuged at 2000 × g for 5 min. Finally, 1 mL of or under natural light only (CK) did not show any significant difference supernatant was read at 503 and 444 nm with a spectrophotometer in weight loss during storage (Table 1). Unfortunately, few researchers (Biochrom Ltd, Cambridge, England). have investigated the effects of pre-harvest LED light on tomato The lycopene content was calculated using the following formula post-harvest quality, often without reporting the weight loss effect. In (Anthon and Barrett, 2006): ( ) ( ) Affandi et al. (2020), Far-Red light added to a Red and Blue base illu­ mg x mination has been found effective in reducing the relative weight loss of lycopene = × A503 × 3.12, kg y tomatoes during storage. The reduction in weight losses caused by Far-Red addition was related to an increase in cuticular thickness where x is the volume of hexane phase (mL, see below), y the weight of leading to a reduced transpiration rate (Cozmuta et al.,2016). Interest­ the fruit tissue (g), A503 is the absorbance at 503 nm, and 3.12 is the ingly, in our experiments, all light treatments applied during cultivation extinction coefficient. β-carotene was calculated with the following resulted in a higher fruit skin hardness after 7 d of storage, suggesting equation (Anthon and Barrett, 2006): that supplementary LED light may have increased cuticle thickness. This V hypothesis is further corroborated by the fact that light treatments β-carotene = (9.38 × A444 − 6.70 × A503 ) × 0.55 × 537 × W , influenced only skin hardness but not flesh firmness (Fig. 1). Light could affect skin hardness and flesh firmness differently, considering that the where A444 is the absorbance at 444 nm, A503 is the absorbance at two instruments have different evaluation parameters. For example, by 503 nm, 0.55 is the ratio of the final hexane layer volume to the volume measuring the elasticity of the peel, Durofel index can be more 3 E. Appolloni et al. Postharvest Biology and Technology 195 (2023) 112113 Table 1 Mean values ± SD of qualitative parameters not reporting statistical difference (p < 0.05) among treatments, at harvest (T0) and after one week of storage (T7). CK RB FR EOD T0 T7 T0 T7 T0 T7 T0 T7 Destructive analysis Soluble solids (%) 4.3 ± 0.3 4.1 ± 0.3 4.0 ± 0.3 4.0 ± 0.3 4.2 ± 0.1 4.1 ± 0.3 3.9 ± 0.2 4.3 ± 0.2 Acidity (g L-1) 3.9 ± 0.6 3.3 ± 0.3 4.1 ± 0.5 3.4 ± 0.4 4.2 ± 0.1 3.8 ± 0.2 3.4 ± 0.3 4.3 ± 0.3 Non-destructive analysis L* 41.4 ± 0.8 40.3 ± 1.0 41.7 ± 1.8 40.8 ± 1.3 42.5 ± 1.3 40.9 ± 1.6 40.4 41.7 ± 1.1 ± 0.6 a* 23.1 ± 0.7 23.5 ± 1.6 23.8 ± 1.6 22.3 ± 2 24.2 ± 1.9 22.4 ± 2.2 21.0 25.2 ± 1.8 ± 1.6 b* 30.5 ± 0.9 30.2 ± 1.0 30.2 ± 1.5 28.8 ± 1.5 30.9 ± 1.7 30.0 ± 1.4 28.5 31.1 ± 1.0 ± 0.9 h 0.9 ± 0.02 0.9 ± 0.02 0.9 ± 0.01 0.9 ± 0.03 0.9 ± 0.03 0.9 ± 0.03 0.9 0.9 ± 0.03 ± 0.02 C 38.3 ± 0.9 38.3 ± 1.7 38.5 ± 2.1 36.5 ± 2.3 39.3 ± 2.3 37.4 ± 2.3 35.4 40.0 ± 1.8 ± 1.6 Weight loss (%) * 2.2 ± 0.7 1.6 ± 0.6 1.4 ± 1.4 1.8 ± 0.9 Biochemical analysis Phenols (GA 100 g-1) 29.0 ± 5.3 26.5 ± 1.5 32.19 ± 5.0 26.7 ± 2.3 26.0 ± 2.5 24.5 ± 2.2 26.0 24.9 ± 2.8 ± 2.3 Antioxidant activity (mmol Fe2+ 100 g-1) 0.3 ± 0.1 0.3 ± 0.02 0.3 ± 0.03 0.3 ± 0.03 0.3 ± 0.05 0.3 ± 0.05 0.3 ± 0.4 0.2 ± 0.05 *Considering the difference between T0 and T7 Fig. 1. a) Fruit hardness (Durofel Index, DI) after 0 and 7 d of storage (p < 0.05). b) Flesh firmness (N) after 0 and 7 d of storage (p < 0.05). In charts, vertical bars indicate SD, different letters indicate significant differences at p < 0.05. influenced by the percentage fruit water content than the penetration tomatoes grown under supplemental LED light was already observed by evaluation. the previous research on the effects of pre-harvest LED light on stored The visual and sensorial parameters which have a more immediate tomatoes by Affandi et al. (2021). However, the same research observed effect on the consumers’ perception and acceptance of the product are a reduction in NAI (Normalized Anthocyanin Index) values as the cold color, sweetness, acidity and consistency of the pulp. This research did storage period continued, highlighting a possible process of pigment not show any significant variation between treatments (Table 1), neither degradation (Farneti et al., 2012). Regarding fruit sweetness and acidity, at the time of harvesting nor after one week of storage, in any of the the absence of differences at harvest time was already observed in pre­ commercial quality and organoleptic parameters described above. At vious research (Dzakovich et al., 2015, 2017; Paucek et al., 2020). the beginning of the storage, fruits used for the experiments were Several harvest and post-harvest factors affecting fruit metabolic pro­ selected at the same ripening level using the DA-Meter. Accordingly, cesses can influence the taste and flavor of tomato fruit during storage they did not present any color difference among treatments, both for (Žnidarčič et al., 2010; Beckles, 2012). In our case, the absence of dif­ color parameters (a*, b* and L*) and for color indices (h and C). After ferences in soluble solids and acidity among treatments after one week one week, lighting regimes did not affect colors attributes (Table 1). The of storage may be imputed to the advanced ripening stage at harvesting absence of color changes at the end of the storage period of ripe red time, having reached the higher amount of storable sugars in fruit while 4 E. Appolloni et al. Postharvest Biology and Technology 195 (2023) 112113 Fig. 2. a) Lycopene content (mg kg-1) after 0 and 7 d of storage (p < 0.05), (n = 8). b) β-carotene content (mg kg-1) after 0 and 7 d of storage (p < 0.05), (n = 8). In charts, vertical bars indicate SD, different letters indicate significant differences at p < 0.05. still attached to the plant (Arias et al., 2000; Carrari et al., 2006), in green-mature tomatoes by 2.3-fold (Alba et al., 2000). In our research, without incurring in soluble solids respiration and consequent reduction it was observed that lycopene content at harvest time did not differ during one week of storage (Kader, 1987; Sualeh et al., 2016). significantly between treatments. This observation seems to contrast The results of the analysis of antioxidant capacity and total phenols with the former hypothesis that associates LED light applied during content did not show significant differences between treatments, either pre-harvest with increases in the lycopene content in tomatoes (Ngcobo at the beginning or at the end of the storage period (Table 1). However, et al., 2020; Dannehl et al., 2021), although our observation may be it is well known that light composition affects the expression of genes related to the uniformity of the fruits used for the storage, all at an that modulate the synthesis of secondary metabolites, including advanced stage of ripeness. However, after one week of storage, the phenolic compounds, although such effects may depend on specific treatments showed a significant difference in carotenoids (lycopene and wavelength and/or plant species (Gupta, 2017; Baenas et al., 2021; β-carotene) content, particularly between CK grown under natural light Appolloni et al., 2022). Concerning the antioxidant capacity, several only and the RB treatment (Fig. 2a and Fig. 2b). In the case of FR and authors have reported an increase in response to the application of LED EOD treatments, no significant differences were observed compared to lighting during the storage of tomatoes, either when a UV or Red and CK, although the carotenoid content was still higher (Fig. 2a and Blue LED light was used (Liu et al., 2011; Baenas et al., 2021). However, Fig. 2b). An increase in red color of tomatoes is usually associated with several other factors contribute to fruit’s antioxidant capacity, including an increase in carotenoids content (Carrillo-López and Yahia, 2014). In climatic factors and ripeness (Valiulina et al., 2015), which may have our case, the tomatoes used for the post-harvest measures were selected masked the light-induced increase in antioxidant capacity. In fact, at an advanced mature-red stage, possibly having achieved the overripe fruit tends to lose antioxidant capacity compared to unripe maximum synthesis of carotenoids. For this reason, it is possible to hy­ (Valiulina et al., 2015), probably masking a possible effect among the pothesize that the differences observed at T7 are more attributable to a different treatments in our case. Palmitessa et al. (2011) reported an different decay time of carotenoids instead to the biosynthesis of new increase in antioxidant capacity, specifically for the lipophilic fraction, molecules. Indeed, it has been observed that lycopene in red tomatoes also in freshly harvested tomatoes grown with supplemental LED light. stored at 13 ◦ C tends to undergo a decay process (Farneti et al., 2012). Notably, lycopene has been described as a potent antioxidant and the most active in the organic phase against free radicals (Cano et al., 2003; 5. Conclusions Baenas et al., 2021), and its content after the storage is higher in RB-treated samples and lowest in CK ones (Fig. 2a). The absence of The research demonstrated that supplementary LED lighting applied differences in antioxidant capacity in our analysis could be associated during the cultivation of greenhouse tomatoes might allow maintaining with the hydrophilic extraction adopted in our protocol (Srivastava and hardness and carotenoid content in mature-red tomatoes after a stan­ Srivastava, 2015). Concerning total phenols content, both studies that dard commercial storage period at 13 ◦ C for one week. The observed directly applied LED light to tomatoes during post-harvest (Kokalj et al., results on increased fruit hardness are of particular interest from the 2016; Baenas et al., 2021) and additional LED light in pre-harvest standpoint of post-harvest handling and transportation losses. A greater without post-storage evaluations (Dzakovich et al., 2017), would seem skin hardness, which may lead to lower transpiration, can have positive to confirm little effect on these compounds. However, the lack of sig­ effects on the reduction of food waste due to mechanical damages and nificant differences among treatments at T0 and T7 in our research weight loss during post-harvest. The absence of alteration of organo­ (Table 1) might be driven by a too short storage time (Bravo et al., 2012; leptic features, such as color, sweetness, acidity and consistency of the Liu et al., 2012; Baenas et al., 2021), which could have limited the pulp, may represent a positive aspect for consumers, maintaining un­ differences among treatments also in terms of decay. The present changed the habitual perception of the product and consequent its research decided to apply a standard commercial storage of one week as marketability. Concerning nutritional value, the higher presence of ca­ practiced by the farm. However, future research might consider more rotenoids after one week in fruit belonging to plants exposed to LED extended storage periods, using time as a factor to statistically confirm lighting may be a sign of a slower decay of product compounds, with observations. Finally, the differential results from existing literature positive consequences on preserving nutritional properties throughout could also be associated with a different response to the lighting treat­ time. The results open to future perspectives concerning supplemental ment associated with genotypic determinants (Mditshwa et al., 2017). LED light application to reduce food losses and maintain nutritional Carotenoid biosynthesis appears to be stimulated by Red and Blue traits during post-harvest storage. As preliminary research, future de­ LED light due to modulation of gene expression and light receptors velopments could focus on analysis considering a longer time factor, (Mditshwa et al., 2017; Baenas et al., 2021). In particular, phytochrome including tomatoes harvested in earlier stages of development than red- appears to be the light receptor most involved in lycopene synthesis, mature. Research should also develop toward the evaluation of other being observed that Red light treatment can increase lycopene content crops besides tomato, as well as cost-benefit analysis in terms of the 5 E. Appolloni et al. Postharvest Biology and Technology 195 (2023) 112113 economic value of food savings compared to costs of LED light appli­ Appolloni, E., Orsini, F., Pennisi, G., Gabarrell Durany, X., Paucek, I., Gianquinto, G., 2021. Supplemental LED lighting effectively enhances the yield and quality of cation. Finally, since the application of LED light may only have an effect greenhouse truss tomato production: results of a meta-analysis. 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The research leading to this publication has received funding from Baenas, N., Iniesta, C., González-Barrio, R., Nuñez-Gómez, V., Periago, M.J., García- the European Union’s Horizon 2020 research and innovation program Alonso, F.J., 2021. Post-harvest use of ultraviolet light (UV) and light emitting diode under grant agreement No 862663, and from the Italian Ministry of (LED) to enhance bioactive compounds in refrigerated tomatoes. Molecules 26 (7), 1847. https://doi.org/10.3390/molecules26071847. Agricultural, Food and Forestry Policies (MIPAAF), in the framework of Balibrea, M.E., Martínez-Andújar, C., Cuartero, J., Bolarín, M.C., Pérez-Alfocea, F., 2006. the project “Light on Shelf Life” (CUP J56J20000410008). The high fruit soluble sugar content in wild Lycopersicon species and their hybrids with cultivars depends on sucrose import during ripening rather than on sucrose metabolism. Funct. Plant Biol. 33 (3), 279–288. https://doi.org/10.1071/fp05134. CRediT authorship contribution statement Beckles, D.M., 2012. Factors affecting the postharvest soluble solids and sugar content of tomato (Solanum lycopersicum L.) fruit. Postharvest Biol. Technol. 63 (1), 129–140. Elisa Appolloni: Methodology, Formal analysis, Investigation, Data https://doi.org/10.1016/j.postharvbio.2011.05.016. Benzie, I.F., Strain, J.J., 1999. Ferric reducing/antioxidant power assay: direct measure curation, Writing – original draft. Giuseppina Pennisi: Conceptualiza­ of total antioxidant activity of biological fluids and modified version for tion, Methodology, Writing – original draft, Writing – review & editing, simultaneous measurement of total antioxidant power and ascorbic acid Visualization, Supervision. Ivan Paucek: Resources, Data curation. concentration. Method Enzymol. 299, 15–27. https://doi.org/10.1016/s0076-6879 (99)99005-5. Antonio Cellini: Resources, Data curation. Andrea Crepaldi: Re­ Bravo, S., García-Alonso, J., Martín-Pozuelo, G., Gómez, V., Santaella, M., Navarro- sources. Francesco Spinelli: Conceptualization, Visualization, Super­ González, I., Periago, M.J., 2012. The influence of post-harvest UV-C hormesis on vision, Project administration, Funding acquisition. Giorgio lycopene, β-carotene, and phenolic content and antioxidant activity of breaker Gianquinto: Supervision. X. Gabarell: Supervision. Francesco Orsini: tomatoes. Food Res. Int. 49, 296–302. https://doi.org/10.1016/j. foodres.2012.07.018. Conceptualization, Methodology, Writing – original draft, Writing – Cano, A., Acosta, M., Arnao, M.B., 2003. Hydrophilic and lipophilic antioxidant activity review & editing, Visualization, Supervision, Project administration, changes during on-vine ripening of tomatoes (Lycopersicon esculentum Mill.), 2003 Funding acquisition. Postharvest Biol. Technol. 28 (1), 59–65. https://doi.org/10.1016/s0925-5214(02) 00141-2. Carrari, F., Baxter, C., Usadel, B., Urbanczyk-Wochniak, E., Zanor, M.I., Nunes-Nesi, A., Declaration of Competing Interest Fernie, A.R., 2006. Integrated analysis of metabolite and transcript levels reveals the metabolic shifts that underlie tomato fruit development and highlight regulatory aspects of metabolic network behavior, 2006 Plant Physiol. 142 (4), 1380–1396. The authors declare the following financial interests/personal re­ https://doi.org/10.1104/pp.106.088534. lationships which may be considered as potential competing interests: Carrillo-López, A., Yahia, E.M., 2014. Changes in color-related compounds in tomato ACr was employed by company Flytech srl. All other authors declare fruit exocarp and mesocarp during ripening using HPLC-APcI+-mass Spectrometry. J. Food Sci. Technol. 51 (10), 2720–2726. https://doi.org/10.1007/s13197-012- that the research was conducted in the absence of any commercial or 0782-0. financial relationships that could be construed as a potential conflict of Cozmuta, A.M., Cozmuta, L.M., Peter, A., Nicula, C., Vosgan, Z., Giurgiulescu, L., interest. Baia, M., 2016. Effect of monochromatic Far-Red light on physical-nutritional- microbiological attributes of red tomatoes during storage. Sci. Hortic. 211, 220–230. https://doi.org/10.1016/j.scienta.2016.08.031. Data availability Dannehl, D., Schwend, T., Veit, D., Schmidt, U., 2021. Increase of yield, lycopene, and lutein content in tomatoes grown under continuous PAR spectrum LED lighting. Front. Plant Sci. 12, 299. https://doi.org/10.3389/fpls.2021.611236. Data will be made available on request. Demotes-Mainard, S., Péron, T., Corot, A., Bertheloot, J., Le Gourrierec, J., Pelleschi- Travier, S., Sakr, S., 2016. 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