Tomato Processing By-products Research Articles

Optimization of lycopene extraction from tomato processing by-products with essential oils and effect of extract on oxidative stability of refined olive oil

Optimization of lycopene extraction from tomato processing by-products with essential oils and effect of extract on oxidative stability of refined olive oil

Valorisation of tomato pomace in anti-pollution and microbiome-balance face cream

Tomato pomace, the main by-product of tomato processing, is also an underestimated source of many active substances. This study aimed to determine the possibility of using oil obtained from tomato pomace in a face cream formulation. The bacterial community structure, face skin biophysical parameters and protection against air pollution were examined after daily application of the cosmetic by volunteers. In the tomato pomace oil, the profile of fatty acids was determined by GC‒MS, and the profile of volatile compounds was determined using the HS-SPME technique. The dominant bioactive component in the oil was linoleic acid (63.6%), and among the volatile compounds, it was carvotanacetone (25.8%). The application of the cream with tomato pomace oil resulted in an increase in the dominant genera Staphylococcus, Anaerococcus and Cutibacterium in the epibiome, particularly beneficial Staphylococcus epidermidis, while limiting the growth of the potentially opportunistic pathogens Kocuria spp., Micrococcus spp., Veillonella spp., and Rothia spp. This study showed the usefulness of tomato pomace oil as a natural ingredient in skin care cosmetics, reducing skin inflammation, sensitivity and melanin level, with potential protective effects against air pollution and microbiome-balance properties. Tomato pomace, which is commonly considered waste after tomato processing, can be used in the development of new cosmetics and may additionally contribute to reducing environmental nuisance.

Valorization of tomato processing by-products: Predictive modeling and optimization for ultrasound-assisted lycopene extraction

Lycopene is a carotenoid highly valuable to the food, pharmaceutical, dye, and cosmetic industries, present in ripe tomatoes and other fruits with a distinctive red color. The main source of lycopene is tomato crops. This bioactive component can be successfully isolated from tomato processing waste, commonly called tomato pomace, mostly made from tomato skins, seeds, and some residual tomato tissue. The main investigative focus in this work was the application of green engineering principles in each stage of the optimized ultrasound-assisted extraction (UAE) of enzymatically treated tomato skins to obtain functional extracts rich in lycopene. The experimental plan was designed to determine the influence of studied operating parameters: enzymatic reaction time (60, 120, and 180 min), extraction time (0, 5, 10, 15, 30, 60, and 120 min), and temperature (25, 35 and 45 ℃) on lycopene yield. Process optimization was performed based on the yield of lycopene [1018, 1067, and 1120 mg/kg] achieved at optimal operating conditions. An artificial neural network (ANN) model was developed and trained for predictive modeling of the closed extraction system, with operating parameters used as input neurons and experimentally obtained values for lycopene content defined as the output neural layer. Applied ANN architecture provided a high correlation of experimental output with ANN-generated data (R=0.99914) with a model deviation error for the entire data set of RMSE=5.3 mg/kg. The k-Nearest Neighbor algorithm was introduced to predict lycopene yield using experimental key features: operating temperature, extraction time, and time of enzymatic treatment, split into training and testing sets with an 85/15 ratio. The model interpretation was conducted through the SHAP (SHapley Additive exPlanations) methodology.

Tomato seed extract promotes health of the gut microbiota and demonstrates a potential new way to valorize tomato waste.

The current effort to valorize waste byproducts to increase sustainability and reduce agricultural loss has stimulated interest in potential utilization of waste components as health-promoting supplements. Tomato seeds are often discarded in tomato pomace, a byproduct of tomato processing, yet these seeds are known to contain an array of compounds with biological activity and prebiotic potential. Here, extract from tomato seeds (TSE), acquired from pomace, was evaluated for their ability to effect changes on the gut microbiota using an ex vivo strategy. The results found that TSE significantly increased levels of the beneficial taxa Bifidobacteriaceae in a donor-independent manner, from a range of 18.6-24.0% to 27.0-51.6% relative abundance following treatment, yet the specific strain of Bifidobacteriaceae enhanced was inter-individually variable. These structural changes corresponded with a significant increase in total short-chain fatty acids, specifically acetate and propionate, from an average of 13.3 to 22.8 mmol/L and 4.6 to 7.4 mmol/L, respectively. Together, these results demonstrated that TSE has prebiotic potential by shaping the gut microbiota in a donor-independent manner that may be beneficial to human health. These findings provide a novel application for TSE harvested from tomato pomace and demonstrate the potential to further valorize tomato waste products.

High-Pressure Homogenization for Enhanced Bioactive Recovery from Tomato Processing By-Products and Improved Lycopene Bioaccessibility during In Vitro Digestion.

The principles of industrial ecology have emerged as pivotal drivers of eco-innovation, aiming to realize a "zero-waste" society where waste materials are repurposed as valuable resources. In this context, High-Pressure Homogenization (HPH) presents a promising, easily scalable micronization technology, capable of enhancing the extractability and bioaccessibility of bioactive compounds found in tomato processing by-products, which are notably abundant waste streams in the Mediterranean region. This study focuses on optimizing HPH treatment parameters to intensify the recovery of bioactive compounds from tomato pomace. Additionally, it investigates the multifaceted impacts of HPH on various aspects, including color, particle size distribution, microscopic characteristics, surface properties, bioactivity, and lycopene bioaccessibility through in vitro digestion simulations. The results demonstrate that the application of HPH under optimized conditions (80 MPa, 25 °C, 10 passes) induces a remarkable 8-fold reduction in mean particle size, reduced surface tension, improved physical stability, uniform color, increased total phenolic content (+31%), antioxidant activity (+30%), dietary fiber content (+9%), and lycopene bioaccessibility during the intestinal digestion phase compared to untreated samples. These encouraging outcomes support the proposition of integrating HPH technology into an environmentally friendly industrial process for the full valorization of tomato processing residues. By utilizing water as the sole solvent, this approach aims to yield a functional ingredient characterized by greater nutritional and health-promoting values.

Utilization of Agro-Industrial By-Products for Sustainable Poultry Production

Agro-industrial by-products (AIBPs) that are not intended for human consumption can be used as alternatives to conventional feedstuffs in animal nutrition to produce animal products without competing for land or triggering the food-feed competition, thus leading to environmental, social, and economic sustainability. These by-products are also known to contain several bioactive compounds and have a potential to become nutraceuticals that can promote the health and well-being of poultry. The potentials of some AIBPs (e.g., fruit juice industry leftovers, oilseed industrial by-products, distillers’ grain by-products, vinification by-products, olive oil industry by-products, pomegranate by-products, tomato processing by-products) and their derivative products as functional feeds for poultry, but also potential limitations of utilizing AIBPs in poultry nutrition are elaborated in the present review. The possible mechanisms through which AIBPs may improve the health status and productivity of poultry are also discussed. We suggest that nutrient variability across countries should be stabilized and potential hazards such as mycotoxins and pesticides should be eliminated, and the potential hazards present in AIBPs (e.g., mycotoxins) should be better controlled through appropriate legislation and proper application of control measures. Modern processing methods, new types/classifications, and proper developmental strategies foster the utilization of AIBPs in animal nutrition. This review focuses on the AIBPs as feeds, not only for their nutritional value but also for their contribution to sustainable practices.

Tomato Processing By-Products Valorisation through Ohmic Heating Approach

Tomato by-products from processing industries have a higher potential to be reused as a source of bioactive compounds. Reliable national data on tomato by-products and physicochemical characterisation that will inform and find effective planning on tomato waste management in Portugal is absent. To help obtain this knowledge, selected Portugal companies were recruited to obtain representative samples of by-products generation, and physicochemical composition was evaluated. Furthermore, an environmental-friendly method (the ohmic heating (OH) method, which allows the recovery of bioactive compounds in absence of hazardous reagents) was also used and compared with conventional methods to explore new safe value-added ingredients. Total antioxidant capacity and total and individual phenolic compounds were also evaluated by spectrophotometric and high-performance liquid chromatography (HPLC), respectively. Tomato processing by-products have revealed a higher potential since both collected samples from companies were rich in protein (between 16.3 to 19.4 g/100 g DW, with fibre content ranging from 57.8 to 59.0 g/100 g DW). In addition, these samples contain 17.0 g/100 g of fatty acids (mainly polyunsaturated, monounsaturated and saturated, such as linoleic, oleic, and palmitic acid, respectively). Also, they present mainly chlorogenic acid and rutin as phenolic compounds. After understanding its composition, the OH was applied to determine added-value solutions to tomato by-products. With extractions, two types of fractions were obtained, namely liquid fraction rich in phenols, free sugars, and carotenoids and a solid fraction rich in fibre bound to phenols and carotenoids. This treatment has been shown to have the ability to preserve carotenoids, such as lycopene relative to conventional methods. Nevertheless, new molecules were identified by LC-ESI-UHR-OqTOF-MS analysis, such as phene-di-hexane and N-acethyl-D-tryptophan. According to the results, the OH boosts the potential of tomato by-products and can be directly introduced into the process, contributing to the circular economy and zero by-products.

A Comprehensive Overview of Tomato Processing By-Product Valorization by Conventional Methods versus Emerging Technologies

The tomato processing industry can be considered one of the most widespread food manufacturing industries all over the world, annually generating considerable quantities of residue and determining disposal issues associated not only with the wasting of invaluable resources but also with the rise of significant environmental burdens. In this regard, previous studies have widely ascertained that tomato by-products are still rich in valuable compounds, which, once recovered, could be utilized in different industrial sectors. Currently, conventional solvent extraction is the most widely used method for the recovery of these compounds from tomato pomace. Nevertheless, several well-known drawbacks derive from this process, including the use of large quantities of solvents and the difficulties of utilizing the residual biomass. To overcome these limitations, the recent advances in extraction techniques, including the modification of the process configuration and the use of complementary novel methods to modify or destroy vegetable cells, have greatly and effectively influenced the recovery of different compounds from plant matrices. This review contributes a comprehensive overview on the valorization of tomato processing by-products with a specific focus on the use of "green technologies", including high-pressure homogenization (HPH), pulsed electric fields (PEF), supercritical fluid (SFE-CO2), ultrasounds (UAE), and microwaves (MAE), suitable to enhancing the extractability of target compounds while reducing the solvent requirement and shortening the extraction time. The effects of conventional processes and the application of green technologies are critically analyzed, and their effectiveness on the recovery of lycopene, polyphenols, cutin, pectin, oil, and proteins from tomato residues is discussed, focusing on their strengths, drawbacks, and critical factors that contribute to maximizing the extraction yields of the target compounds. Moreover, to follow the "near zero discharge concept", the utilization of a cascade approach to recover different valuable compounds and the exploitation of the residual biomass for biogas generation are also pointed out.

Sustainable Valorization of Tomato Pomace (Lycopersicon esculentum) in Animal Nutrition: A Review.

Under the background of the current shortage of feed resources, especially the shortage of protein feed, attempts to develop and utilize new feed resources are constantly being made. If the tomato pomace (TP) produced by industrial processing is used improperly, it will not only pollute the environment, but also cause feed resources to be wasted. This review summarizes the nutritional content of TP and its use and impact in animals as an animal feed supplement. Tomato pomace is a by-product of tomato processing, divided into peel, pulp, and tomato seeds, which are rich in proteins, fats, minerals, fatty acids, and amino acids, as well as antioxidant bioactive compounds, such as lycopene, beta-carotenoids, tocopherols, polyphenols, and terpenes. There are mainly two forms of feed: drying and silage. Tomato pomace can improve animal feed intake and growth performance, increase polyunsaturated fatty acids (PUFA) and PUFA n-3 content in meat, improve meat color, nutritional value, and juiciness, enhance immunity and antioxidant capacity of animals, and improve sperm quality. Lowering the rumen pH and reducing CH4 production in ruminants promotes the fermentation of rumen microorganisms and improves economic efficiency. Using tomato pomace instead of soybean meal as a protein supplement is a research hotspot in the animal husbandry industry, and further research should focus on the processing technology of TP and its large-scale application in feed.

Natural Polyphenol Recovery from Apple-, Cereal-, and Tomato-Processing By-Products and Related Health-Promoting Properties.

Polyphenols of plant origin are a broad family of secondary metabolites that range from basic phenolic acids to more complex compounds such as stilbenes, flavonoids, and tannins, all of which have several phenol units in their structure. Considerable health benefits, such as having prebiotic potential and cardio-protective and weight control effects, have been linked to diets based on polyphenol-enriched foods and plant-based products, indicating the potential role of these substances in the prevention or treatment of numerous pathologies. The most representative phenolic compounds in apple pomace are phloridzin, chlorogenic acid, and epicatechin, with major health implications in diabetes, cancer, and cardiovascular and neurocognitive diseases. The cereal byproducts are rich in flavonoids (cyanidin 3-glucoside) and phenolic acids (ferulic acid), all with significant results in reducing the incidence of noncommunicable diseases. Quercetin, naringenin, and rutin are the predominant phenolic molecules in tomato by-products, having important antioxidant and antimicrobial activities. The present understanding of the functionality of polyphenols in health outcomes, specifically, noncommunicable illnesses, is summarized in this review, focusing on the applicability of this evidence in three extensive agrifood industries (apple, cereal, and tomato processing). Moreover, the reintegration of by-products into the food chain via functional food products and personalized nutrition (e.g., 3D food printing) is detailed, supporting a novel direction to be explored within the circular economy concept.

Exploring the Potential of Tomato Processing Byproduct as a Natural Antioxidant in Reformulated Nitrite-Free Sausages

This study evaluated the potential of two dried processing by products, obtained from large and cherry tomatoes (LT and CT) after juice extraction to improve the oxidative stability of pork sausages during refrigerated storage for 20 days. For this purpose, reformulated nitrite-free sausages were manufactured by supplementation of raw sausage samples with dried large and cherry tomato processing byproducts (DLTB and DCTB) at a dose that provides a level of polyphenolic compounds equally with 50, 90, 180 and 270 mg gallic acid equivalents (GAE)/kg of processed meat. The developed sausage formulas were subjected to heat treatment, such as smoking and drying and, smoking and scalding, respectively. The reformulated nitrite-free sausages were compared with control samples of sausages with or without the addition of sodium nitrite. Large and cherry tomatoes and their raw and dried processing byproducts were investigated for total and individual polyphenols content as well as lycopene content. The sausage formulas were evaluated in terms of proximate composition. Additionally, the progress of lipid oxidation developed in sausage formulas was assessed by specific indices, such as peroxide value (PV), p-anisidine value (p-AV), TOTOX value and thiobarbituric acid reactive substances (TBA), after 1, 10 and 20 days of storage at 4 °C. Based on the values of PV, p-AV, TOTOX and TBA, it can be stated that the dried tomato processing byproducts applied at doses that ensure a level of polyphenolic compounds of at least 180 mg GAE/kg of processed meat for DCTB and 270 mg GAE/kg of processed meat for DLTB, showed promising potential to replace sodium nitrite in meat products for both dried and scalded sausage formulas. For the same dose of tomato processing byproducts, it was noted a stronger inhibitory effect against lipid oxidation in the case of smoked and scalded sausages compared to smoked and dried ones.

Valorization Strategies for a By-Product of Organic Tomato Processing as Potential Ingredient in Functional Food Formulations

Production of tomato-based products generates 5% of waste, composed mainly of peel. This has a significant amount of carotenoids, such as lycopene, and an appropriate amount of total dietary fiber (TDF). Both carotenes and dietary fiber are known to have functional effects on the human body. Therefore, the aim of this research was mainly divided into two parts. First, organic tomato peel obtained by a local processing industry was characterized in terms of percentage of macronutrients such as dietary fiber, protein, and ash, as well as total carotenoid content. Second, two valorization alternatives of these compounds as potential functional additives in food processing were proposed. The first one included carotenoid extraction using ultrasound-assisted extraction (UAE), the encapsulation of the enriched carotenoid extract using spray-drying technology, and its subsequent analysis of powder properties. The second one evaluated the potential use of TDF tomato peel as a replacement for fat and flour in four formulations of cookies. Each formulation was assessed using physicochemical, texture, sensory, and theoretical proximal analyses. The results revealed that UAE optimization was performed using a solvent ratio of 80:20 ethyl acetate:ethanol and 2.5% w/v of solvent:biomass ratio. The recovery percentage of total carotenoid content was 89.08%. The TDF content was 49.46 (3.91) g/100 g on a dry basis. For encapsulation, the drying yield and encapsulation efficiencies were 67.3% (0.5) and 58.1% (0.8), respectively. Sensory analysis showed no significant difference between the means for the control cookie and the 30% fat replacement cookie. Moreover, these 30% fat replacement cookies had the highest purchase intention by the consumers. This study presented a solution for unused tomato peel industrial byproducts, promoting the design of new functional food products with a high content of carotenes and dietary fiber, thereby increasing nutritional and health benefits for consumers.

Carotenoid Recovery from Tomato Processing By-Products through Green Chemistry.

The recovery of bioactive compounds from agro-industry-derived by-products sustains circular economy principles by encouraging maximized recycling and minimized waste. Tomato processing by-products are abundant in carotenoids, which have several health-promoting properties, and their reintegration into functional food products represents a major interest for scientists and manufacturers. In the present study, carotenoids were recovered from tomato processing by-products based on the principles of green chemistry by using generally recognized as safe (GRAS) solvents, freeze-drying as pretreatment, and ultrasound in the recovery procedure. Spectrophotometric measurements and HPLC were used to identify and quantify total and individual carotenoids from the extracts. The highest values for lycopene (1324.89 µg/g dw) were obtained when ethyl lactate was applied as a solvent, followed by ethyl acetate with slightly smaller differences (1313.54 µg/g dw). The extracts obtained from freeze-dried samples presented significantly lower amounts of lycopene, indicating that carotenoids are highly susceptible to degradation during lyophilization. Flaxseed, grape seed, and hempseed oils were enriched with carotenoids and their rheological measurements showed favorable viscoelastic properties, especially hempseed and flaxseed oil, with viscosity under 50 mPa·s. Considering the results and the economic perspective of carotenoid recovery from tomato processing by-products, ethyl acetate is suitable, sustainable, and environmentally friendly for carotenoid extraction.

The structural and functional characteristics of soluble dietary fibers modified from tomato pomace with increased content of lycopene

The tomato pomace, a by-product of tomato processing, was rich in nutrients such as lycopene (Lyc), vitamins, phenols and soluble dietary fibers (SDF). Homogenization combined with enzymatic hydrolysis (HE) was firstly applied to obtain HE-pomace. The yield of Lyc was raised by 57.2% after HE treatment by the optimal condition. The extraction rate of HE-SDF was increased by 73.4%. In order to clarify the relationship between the SDF and the release of Lyc, SDFs were characterized by structural analysis and morphological determination. The results suggested that HE-SDF possessed smaller molecular weight and loose microstructure with shorter chains. It implied that the degradation of dietary fiber led to the release of Lyc molecules. Besides, HE-SDF exhibited stronger capacity of water-holding, glucose adsorption and bile acid binding. In conclusion, HE treatment possessed the potential to be applied as an excellent modification method, which improved the nutritional and economic value of tomato pomace.

Enhancing the bioaccessibility of lycopene from tomato processing byproducts via supercritical carbon dioxide extraction

Tomato peel and seed from tomato processing industry are treated as waste; however, they contain lycopene, a high-value bioactive compound. In this study, lycopene was extracted from tomato peel and seed using supercritical carbon dioxide (SC–CO2) and hexane, and the bioaccessibilities of lycopene in the SC-CO2- and hexane-extracted oleoresins were investigated for the first time. The (Z)-lycopene content of the SC-CO2-extracted oleoresin (69%) was higher than that of hexane-extracted oleoresin (45%). Separation of the insoluble fraction from the oleoresins increased the (Z)-lycopene contents of the SC-CO2- and hexane-extracted oil fractions to 80% and 49%, respectively. The bioaccessibility of total-lycopene in the oleoresins was increased by 3.3-fold via SC-CO2 extraction, which was attributed to higher (Z)-lycopene content, and small-sized uniform distribution of lycopene in the oleoresin. SC-CO2 extraction is not only a green method for extraction of bioactive compounds, but also has the potential to improve health benefits of bioactive compounds.

Evaluation of the Bioactive Compounds Found in Tomato Seed Oil and Tomato Peels Influenced by Industrial Heat Treatments.

The circular economy action plan involves principles related to food waste reduction and integration of recovered nutrients to the market. In this context, the present study aims to highlight the valuable bioactive components found in tomato processing by-products (carotenoids, phenolic compounds and fatty acids) influenced by industrial pre-treatments, particularly cold break (CB) process at 65–75 °C and hot break (HB) process at 85–95 °C. The fatty acid profile of the tomato seed oil was examined by gas chromatography coupled to mass spectrometry (GC-MS), individual carotenoid and phenolic compositions were determined by high performance liquid chromatography (HPLC) and the viscoelastic properties were evaluated by rheological measurements. The physicochemical properties revealed appropriate characteristics of the tomato seed oil to fit the standards of generally accepted edible oils, for both CB and HB derived samples, however, significant qualitative and quantitative differences were detected in their phenolic composition and carotenoids content. Lycopene (37.43 ± 1.01 mg/100 mL) was a major carotenoid in the examined samples, linoleic acid was the main fatty acid (61.73%) detected in the tomato seed oil and syringic acid appeared to be one of two major phenolic acids detected in the samples of CB process. Our findings extend the boundaries of tomato processing industry by validating that tomato seed oil is a bioactive rich edible oil with additional health benefits, which can be integrated in functional food products.

Development of cold plasma pretreatment for improving phenolics extractability from tomato pomace

In this study, high voltage atmospheric cold plasma (HVACP) with different working gases (air, Ar, He and N2) was used to modify the surface of tomato pomace, aiming to facilitate the migration of phenolic compounds during extraction hence increase their extraction efficiency. In addition to rupturing the epidermal cells of tomato pomace, HVACP treatments were found to decrease the water contact angle of tomato peels and accelerate the drying of tomato fruit, indicating that the treated surfaces were more hydrophilic. Tomato pomace treated by He and N2 plasmas showed increased extraction yields of phenolic compounds by nearly 10%, and all HVACP treatments increased the antioxidant capacity of tomato pomace extracts and slightly changed the concentration profile of their phenolic compounds. The developed HVACP pretreatment technology is a promising method for valorizing tomato processing byproducts with high nutritional values. Industrial relevanceTomato pomace is a good source of phenolic compounds, however, the huge amount generated from commercial tomato processing has caused a severe waste problem. Conventional extraction methods for phenolic compounds are generally time-consuming with intensive use of organic solvents that are thus considered not environment-friendly. This new cold plasma pretreatment method can not only help mitigate the environmental burdens associated with agricultural waste management but also convert waste into value-added functional food ingredients and neutraceuticals in a more efficient way.

Recovery of lycopene from industrially derived tomato processing by-products by pulsed electric fields-assisted extraction

The influence of pulsed electric fields (PEF) pre-treatment at different field strength (E = 1–5 kV/cm) and energy input (WT = 5–10 kJ/kg) on the recovery yield of lycopene in either acetone or ethyl lactate from industrial tomato peels residues, was investigated. The rate of lycopene extraction in both solvents decreased with time and was predicted rather satisfactorily (R2 = 0.96–0.99) by the Peleg's model. Micrograph of tomato peels showed that PEF induced size reduction and separation between the plant cells likely due to pore formation and leakage of intracellular matter. Coherently, PEF treatment (5 kV/cm, 5 kJ/kg) significantly enhanced the extraction rate (27–37%), the lycopene yields (12–18%) and the antioxidant power (18.0–18.2%) in either acetone and ethyl lactate extracts, as compared with untreated samples. However, acetone gave the highest lycopene yield. HPLC analyses revealed that all-trans lycopene was the main carotenoid extracted and no degradation/isomerization phenomena occurred. The results obtained in this work suggest that the application of PEF prior to solid-liquid extraction with environmentally friendly solvents could represent a sustainable approach for the valorization of industrial tomato peels residues. Industrial relevanceIndustrial processing of tomatoes generates large amount of by-products, mainly peels, which represent a cheap and abundant source of natural carotenoids, especially lycopene. The recovery lycopene from tomato peels residues is a crucial step for use in a wide range of industrial applications in food, cosmetic and pharmaceutical sectors as natural pigment and antioxidant. PEF pre-treatment allows to intensify the extractability of lycopene from of tomato processing by-products using environmentally friendly solvents, thus adding new value to the tomato processing chain, improving economic performances and decreasing waste problems.

Antimicrobial and antioxidant properties of tomato processing byproducts and their correlation with the biochemical composition

Tomato processing industry generates high quantities of by-products rich in bioactive compounds such as polyphenols. The present study evaluated the carotenoids, phenolics and amino acids content of ten tomato varieties processing wastes, and the correlation with their antimicrobial and antioxidant properties. Antimicrobial activity was tested against seven microorganisms and the antioxidant capacity of the extracts was assessed with the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. In addition, the fatty acid composition of the tomato seeds was evaluated by GC-MS. Overall, the mean content of total carotenoids, phenolic compounds and amino acids was 30.2 ± 10.8, 242 ± 89 and 3310 ± 1217 mg/100 g dry weight, respectively. Total lipids represented 21% from the tomato seeds, with linoleic acid being the major compound (88% of total lipids). The extracts had good antibacterial activity against Gram-positive bacteria (e.g. Staphylococcus aureus), which correlated well with the amount of isochlorogenic acid in each tomato variety. The antioxidant activity was high for all genotypes, and especially for the Tiny Tim variety which contains significantly higher amounts of flavonol glycosides and isochlorogenic acid than the other varieties. Our results support the need of a better revalorization of tomato processing wastes.

Tunisian tomato waste pyrolysis: thermogravimetry analysis and kinetic study.

This paper aims to set up viable units of thermal processing of numerous agricultural wastes in a sustainable development and eco-friendly approach that could create new economic profitable circuits in an increasingly competitive context. One of the most problematic food wastes are tomato processing by-products; concentrating and canning industrial activities generate important amounts of them, particularly in the Tunisian context. As no reference was found in literature dealing with these last residues, this work intended to explore their potential as biomass fuels. Pyrolysis is then applied in thermogravimetric conditions for different heating rates (5, 10, 20, and 30°C/min) in order to recover energy on one hand and to extract the corresponding kinetic parameters for an accurate design of reactors on the other hand. Main results include suitability of the tomato residues to a thermal valorization thanks to high contents of volatiles and fixed carbon and low ash percentage as well as an interesting heating value comparable to lignocellulosic biomass. Mass loss profiles indicate consecutive and overlapping stages of drying, active pyrolysis, and passive pyrolysis. The experimental profiles of conversion rate were well fitted by the three isoconversional methods; the best fitting is recorded by the Flynn-Wall-Ozawa associated with a first-order model for the intermediate pyrolysis and with a contracted sphere (n = 1/3) for the slowest studied pyrolysis.