Tomato Peel Research Articles

Biorefinery cascade processing for creating added value on tomato industrial by-products from Tunisia.

BackgroundIn today’s consumer perception of industrial processes and food production, aspects like food quality, human health, environmental safety, and energy security have become the keywords. Therefore, much effort has been extended toward adding value to biowastes of agri-food industries through biorefinery processing approaches. This study focused, for the first time, on the valorization of tomato by-products of a Tunisian industry for the recovery of value-added compounds using biorefinery cascade processing.ResultsThe process integrated supercritical CO2 extraction of carotenoids within the oil fractions from tomato seeds (TS) and tomato peels (TP), followed by a batch isolation of protein from the residues. The remaining lignocellulosic matter from both fractions was then submitted to a liquid hot water (LHW) hydrolysis. Supercritical CO2 experiments extracted 5.79% oleoresin, 410.53 mg lycopene/kg, and 31.38 mg β-carotene/kg from TP and 26.29% oil, 27.84 mg lycopene/kg, and 5.25 mg β-carotene/kg from TS, on dry weights. Protein extraction yields, nearing 30% of the initial protein contents equal to 13.28% in TP and 39.26% in TS, revealed that TP and TS are a rich source of essential amino acids. LHW treatment run at 120–200 °C, 50 bar for 30 min showed that a temperature of 160 °C was the most convenient for cellulose and hemicellulose hydrolysis from TP and TS, while keeping the degradation products low.ConclusionsResults indicated that tomato by-products are not only a green source of lycopene-rich oleoresin and tomato seed oil (TSO) and of protein with good nutritional quality but also a source of lignocellulosic matter with potential for bioethanol production. This study would provide an important reference for the concept and the feasibility of the cascade fractionation of valuable compounds from tomato industrial by-products.Graphical abstractSchema of biorefinery cascade processing of tomato industrial by-products toward isolation of valuable fractions.

DNA and mitochondrial protective effect of lycopene rich tomato (Solanum lycopersicum L.) peel extract prepared by enzyme assisted extraction against H2O2 induced oxidative damage in L6 myoblasts

Lycopene rich extracts (ETE) were prepared by enzyme assisted extraction of tomato peel. Oxidative damage was induced in L6 myoblasts by exposing cells to H2O2 in presence and absence (control) of ETE. The potential of ETE to protect cells from oxidative damage was investigated in terms of cytotoxicity (MTT assay), Reactive oxygen species (ROS) by 2′, 7′-dichlorofluorescindiacetate (H2DCFDA), DNA damage (ladder assay, 8-oxo-dG), Hoechst 33342 nuclear staining, mitochondrial stability by ATP production and mitochondrial membrane potential by Rhodamine 123 staining. It was observed that treatment of cells with ETE significantly increased cell viability, decreased ROS production, reduced DNA fragmentation, chromatin condensation & 8-oxo-dG, increased ATP levels and mitochondrial membrane potential. Results indicated that ETE could protect cells from H2O2 induced oxidative damage significantly as compared to control. These results depicted the antioxidant potential of tomato peel extract which can counteract the redox imbalance in cells induced by oxidative stress condition.

Food Industry Co-streams: Potential Raw Materials for Biodegradable Mulch Film Applications

Vast amounts of co-streams are generated from plant and animal-based food processing industries. Efficient utilization of these co-streams is important from an economic and environmental perspective. Non-utilization or under-utilization of co-streams results in loss of potential revenues, increased disposal cost of these products and environmental pollution. At present, extensive research is taking place around the globe towards recycling of co-streams to generate value-added products. This review evaluates various co-streams from food processing industries as raw materials in developing biodegradable agricultural mulching applications. Among the agriculture-based co-streams, potato peels, tomato peels, carrot residues, apple pomace, coffee residues and peanut residues were reviewed with respect to production amount, composition, film forming components and film forming capabilities. Similarly, selected co-streams from slaughterhouses, poultry and fish processing industries were also reviewed and evaluated for the same purpose.

Effect of dry tomato peel supplementation on glucose tolerance, insulin resistance, and hepatic markers in mice fed high-saturated-fat/high-cholesterol diets

Many studies have investigated the effect of crude tomato peel in vivo, but no studies have determined the dose-effect of dry tomato peel (DTP) on glucose intolerance, insulin resistance, and atherogenic dyslipidemia induced by a high-saturated-fat (HSF) diet in vivo. The aim of this study was to investigate the effects of different doses of DTP on the levels of oxidative stress in mice fed an HSF and cholesterol-rich diet for 12 weeks. The main outcomes are glucose and insulin tolerance, plasma lipids, and hepatic steatosis and inflammation. BALB/c male mice (n=40) (8 weeks old, weighing 22.2±1.0 g) were divided into four treatment groups (10 mice/group): (a) high-fat control diet (HF Ctrl), which contains sunflower oil as a sole source of fat; (b) HSF/high-cholesterol (HC) diet; (c) HSF/HC diet supplemented with 9% DTP and (d) HSF/HC diet supplemented with 17% DTP. The HSF/HC diet significantly increased body weight gain, adipose tissue weight, fasting plasma glucose, fasting plasma insulin and lipid peroxidation and caused the development of liver steatosis and inflammation. Supplementation with DTP increased plasma lycopene concentration and reduced the development of indicators of metabolic syndrome, with no consistent effect of the DTP dose. Hepatic steatosis and inflammation were not reversed with DTP supplementation. Among mice fed the HSF/HC diet, DTP supplementation appears to have a beneficial effect on insulin resistance, which confirms the antiatherogenic effect of DTP.

The Choice of Canned Whole Peeled Tomatoes is Driven by Different Key Quality Attributes Perceived by Consumers Having Different Familiarity with the Product.

Canned whole peeled tomatoes are a premium tomato product; however, no information is available about the key intrinsic and extrinsic quality attributes perceived by consumers when buying this product. This research considered consumers differing in the level of familiarity with peeled tomatoes, that is, knowledge, frequency of consumption, and availability of this product, on 3 markets: Chile (low), The Netherlands (medium), and Italy (high). The perceptions and preferences of each group were studied using first focus groups and subsequently conjoint analysis in order to identify the key quality attributes leading their preferences for this product. Focus groups identified 7 intrinsic attributes (color, packing medium, tomato consistency, acidity level, sweetness level, extra ingredients, and intensity of product taste), and 5 extrinsic attributes (packaging material, product type, country of origin, brand, and label design). Significant variations according to the familiarity were found. The conjoint analyses showed that color of tomatoes was the most important intrinsic quality attribute for all groups, while packaging material was the most important extrinsic quality attribute for Chileans and Dutch, being a glass container or a can with easy open the preferred packaging for respective groups. In contrast, country of origin was the most important parameter for Italians. We concluded that intrinsic and extrinsic attributes were strongly influenced by the degree of familiarity with canned whole peeled tomatoes.

Pseudo-component thermal decomposition kinetics of tomato peels via isoconversional methods

The kinetics of the thermal decomposition of tomato peel residues under nitrogen atmosphere was studied by non-isothermal thermogravimetric analysis in the heating rate range 2–40°C/min. Due to the complexity of the kinetic mechanism, which implies simultaneous multi-component decomposition reactions, an analytical approach involving the deconvolution of the overlapping decomposition steps from the overall differential thermogravimetric curves (DTG) and the subsequent application of model-free kinetic methods to the separated peaks was employed. Two freely available Matlab functions, which adopt a non-linear optimization algorithm to decompose a complex overlapping-peak signal into its component parts, were used. Different statistical functions (i.e., Gaussian, Voigt, Pearson, Lorentzian, equal-width Gaussian and equal-width Lorentzian) were tested for deconvolution and the best fits were obtained by using suitable combinations of Gaussian and Lorentzian functions. For the kinetic analysis of the deconvoluted DTG peaks, the Friedman's isoconversional method was adopted, which does not involve any mathematical approximation. The reliability of the derived kinetic parameters was proved by successfully reproducing two non-isothermal conversion curves, which were recorded at a heating rate of 60°C/min and 80°C/min and not included in data set used for the kinetic analysis. Seven pseudo-components were identified as a result of the deconvolution procedure and satisfactorily associated with the main constituents of the investigated tomato peels.

Modelling the chemical free neutralization of caustic peeled tomato slurry as a continuously stirred tank

The purpose of this investigation was to use membrane filtration to neutralize a waste stream from the chemical peeling of tomatoes and to model this process. The waste exiting the peeler/scrubber unit is decanted to separate skins and seeds from the aqueous portion of the waste stream. This aqueous suspension represents the inefficiency in over peeling of tomatoes. Recycling the slurry would reduce waste generated from the peeling operation thereby increasing process efficiency. A constant volume dilution (CVD) membrane filtration process was designed to perform a chemical-free neutralization of the tomato slurry. Through the CVD process, the active alkali of the slurry was reduced from 0.7 to less than 0.01mol/L and electrical conductivity of the suspension decreased from 27 to less than 0.1mS/cm. Additionally, electrical conductivity and active alkali were found to have a linear relationship (r2=0.9962) showing that one value can adequately predict the other in this system. All of the indicators of neutralization fit log-linear to the derived stirred tank processes model with significant correlation coefficients. This work shows that a CVD process using membrane technology has the potential to reclaim tomato waste from caustic peeling and that the filtration can be adequately modelled.

Demonstration Tests of Infrared Peeling System with Electrical Emitters for Tomatoes

. Infrared (IR) dry-peeling is an emerging technology that could avoid the drawbacks of steam and lye peeling of tomatoes. The objectives of this research were to evaluate the performance of an IR peeling system at two tomato processing plants in California and to compare product quality, peelability, and energy consumption of IR and steam peeling. The system was continuously operated using tomatoes of different sizes and cultivars. High percentages (62% to 85%) of fully peeled tomatoes were obtained and varied depending on tomato cultivar and seasonality. IR dry-peeled tomatoes had a firmer texture than steam and lye peeled tomatoes. IR peeling achieved a peeling loss in the range of 17% to 42%, which was lower than typical loss in the industry. Small tomatoes had higher loss than large tomatoes in the late season. Thermal energy consumption of the proposed technology in full-scale production (10 ton h-1) is predicted to be 117.0 and 137.3 MJ ton-1 for indoor and outdoor operation, respectively. The estimated energy savings of IR dry-peeling should be 22% and 28% compared to lye and steam peeling, respectively. The demonstration results showed that the IR dry-peeling technology could be a viable alternative to lye and steam peeling.

Effect of solvent addition sequence on lycopene extraction efficiency from membrane neutralized caustic peeled tomato waste

Lycopene is a high value nutraceutical and its isolation from waste streams is often desirable to maximize profits. This research investigated solvent addition order and composition on lycopene extraction efficiency from a commercial tomato waste stream (pH 12.5, solids ∼5%) that was neutralized using membrane filtration. Constant volume dilution (CVD) was used to desalinate the caustic salt to neutralize the waste. Acetone, ethanol and hexane were used as direct or blended additions. Extraction efficiency was defined as the amount of lycopene extracted divided by the total lycopene in the sample. The CVD operation reduced the active alkali of the waste from 0.66 to <0.01M and the moisture content of the pulp increased from 93% to 97% (wet basis), showing the removal of caustic salts from the waste. Extraction efficiency varied from 32.5% to 94.5%. This study demonstrates a lab scale feasibility to extract lycopene efficiently from tomato processing byproducts.

Antimicrobial Property of Lycopene Oleoresin on some Food Pathogens Running Head: Lycopene oleoresin antibacterial potent

The aim of this work was to study the antimicrobial activity of tomato skin lycopene oleoresin against Pseudomonas aeruginosa، Escherichia coli، Staphylococcus ureuse، Salmonella typh ، L. monocytogenes ، Bacillus cereus، Bacillus licheniformis. Oleoresin was extracted from tomato peel. Lycopene content was measured by spectrophotometer. Lycopene oleoresin contained 2321mg lycopene/ 100 g oleoresin diluted in serial micro-dilution technique from 40,000 to 78.125 ppm. Microbial culturing was done in ELISA 96-well micro-titer plates in triplet and then MIC and MBC were determined. The results were shown that tomato peel oleoresin contained 2% lycopene, can inhibit and restrain the gram positive and negative bacteria.

Torrefaction of Tomato Peel Residues in a Fluidized Bed of Inert Particles and a Fixed-Bed Reactor

The potential of torrefaction treatment for upgrading low-value tomato peel residues into high-quality solid energy carriers was investigated by using a new bench-scale batch experimental apparatus based on fluidized-bed technology. In particular, the influence of the main process variables (i.e., temperature and time) on both the key performance parameters (i.e., mass and energy yields) and the main properties of the solid product (i.e., elemental composition, ash content, calorific value and equilibrium moisture content) was studied. Fluidized bed experimental runs were performed at 200, 240, and 285 °C by keeping the torrefaction time at 5, 15, and 30 min. Results suggested tomato peels as a good candidate for the torrefaction treatment. In more detail, it was observed that higher temperatures and longer holding times (with a more marked effect of the torrefaction temperature) led to an increase in the calorific value of the torrefied tomato peels, with respect to the parent ones. More specifically, th...

Sequence variation in SlMYB12 is associated with fruit peel color in pink tomato cultivars

The peel of pink-colored tomato is transparent due to the lack of accumulation of the flavonoid naringenin chalcone during ripening. A strong correlation was found between flavonoid expression and the function of SlMYB12, which is a transcriptional regulator of flavonoid biosynthesis. Thus, SlMYB12 is a strong candidate gene underlying the pink phenotype. Three allelic variants, a 603 bp deletion, a nucleotide substitution (C > T), and a 1 bp insertion (TG > TAG) in the SlMYB12 gene have been previously reported. We performed PCR genotyping based on these three allelic variations in 47 tomato cultivars displaying either a pink or red phenotype. However, the genotype did not match with the expected phenotype in one pink cultivar “Prime Alexander”. This cultivar was therefore self-pollinated to produce 20 progeny plants. To identify new mutations in SlMYB12, the sequence of genomic DNA and CDS were compared between the progeny 17 and the reference line, Heinz 1706. A novel G > T nucleotide substitution was found in the 2nd intron. This SNP leads to a deletion of 7 bp (GTAACAG) from the end of the 2nd exon, resulting in a premature stop codon. The presence of this SNP associates the pink phenotype with the genotype. This novel SNP will be useful as a genetic marker for marker-assisted breeding of pink tomato.

The Effect of Lycopene Addition on the Chemical Composition, Sensory Attributes and Physicochemical Properties of Steamed and Grilled Turkey Breast

The aim of this study was to determine the effect of lycopene addition to the curing mixture for steamed and grilled breast muscles on the chemical composition, sensory attributes and physicochemical parameters of the final products. The experimental material comprised a total of 48 breast muscles of Hybrid XL turkeys aged 15 weeks and fed commercial pelleted diets. The material was divided into three groups (control, experimental groups I and II). Sixteen breast muscles (8 left and 8 right) were assigned to each group. Control group samples were immediately transported to a laboratory. The remaining 32 muscles were steamed and grilled, where 16 samples were cured before heat treatment. The curing brine contained tomato peel extract standardized for 5% lycopene content. The results of the study indicate that the lycopene increased vitamin E levels and decreased the ash and vitamin A content of the final products. Lycopene also lowered the aroma and flavour scores, and increased the shear force values of the final products. The addition of lycopene lowered the pH of the products measured in a water homogenate and deteriorated the hydration properties of meat. Lycopene increased the darkness and the contribution of redness, which led to an increase in colour saturation and hue values of the evaluated samples. It can be concluded that lycopene exerted antioxidant effects and improved the colour parameters on the external surface and along the cross-section of processed meat. However, the specific flavour of tomatoes deteriorated the sensory attributes of the final products.

Fatty acid profile, total cholesterol, vitamin content, and TBARS value of turkey breast muscle cured with the addition of lycopene

The aim of this study was to determine the effect of lycopene addition for curing turkey meat on the profile of fatty acids, total cholesterol, vitamin content, and the TBARS of the final products. The analyzed material comprised 64 breast muscles, of which 16 (RBM) were immediately transported to a laboratory. Another 16 (UBM) were heat treated in a convection steam oven, and 32 muscles were cured for 3 days in two types of curing mixture: without (CBM) and with (CBM+Lyc) tomato peel extract standardized for 5% lycopene content. After completed curing, samples were steamed and grilled under the same conditions as raw samples. Statistical analysis demonstrated the highest (P ≤ 0.01) mean content of vitamin A (0.07 μg/g) in chilled muscles. The content of vitamin E was lower (P ≤ 0.01) in UBM samples than in CBM+Lyc and RBM. The TBARS value was the lowest (P ≤ 0.01) in RBM muscles (0.35 mg MDA/kg of meat). Although there were no differences between products, but lower TBARS were found in CBM+Lyc samples. The content of cholesterol was higher (P ≤ 0.01) in CBM+Lyc products than in the RBM and UBM. RBM samples contained (P ≤ 0.01) the lowest amount of saturated, monounsaturated, and hypercholesterolemic fatty acids, and the highest of unsaturated, polyunsaturated, and hypocholesterolemic fatty acids. CBM+Lyc samples contained (P ≤ 0.01) less hypercholesterolemic and more hypocholesterolemic fatty acids than CBM group. Higher (P ≤ 0.01) unsaturated/saturated and hypocholesterolemic/hypercholesterolemic fatty acid ratios were also found in CBM+Lyc products. The study demonstrated that the used processing technology caused reduction (P ≤ 0.01) of n-3 and n-6 PUFA content. Findings suggest that the addition of lycopene in the process of meat curing and heat treatment in meat industry do not change the content of vitamins and cholesterol or alter the TBARS value in turkey meat products. Nevertheless, lycopene can be used to increase the content of essential hypocholesterolemic fatty acids and decrease the content of saturated hypercholesterolemic fatty acids.

Detoxification and function of immature tomato

α-Tomatine and chlorophyll (a and b) decreased, and β-carotene and lycopene increased with ripening of tomatoes. α-Tomatine was localised in peel of immature green tomatoes. The dose–response curve of α-tomatine determined by WST-1 (water soluble tetrazolium) assay was the same as that by LDH (lactate dehydrogenase) assay, suggesting that the cytotoxicity of α-tomatine depends on the destruction of plasma membrane. Immature green tomatoes had little cytotoxic effect after one month-incubation with 25% ethanol or 4.5% acetate at 7°C, and α-tomatine was decomposed by crude enzymes extracted from immature green tomatoes. Immature green tomatoes incubated with 4.5% acetic acid inhibited the accumulation of lipid in adipocytes. From the above facts the detoxification and the anti-obesity effect of immature green tomatoes are expected to be controlled by the removal of peel, the enzymatic decomposition or the incubation with 4.5% acetate or 25% ethanol.

Tomato peeling by ohmic heating with lye-salt combinations: Effects of operational parameters on peeling time and skin diffusivity

Ohmic heating without lye has shown promise in tomato peeling; however the use of lye is known to yield high peeled-product quality. In this work, we studied the operational parameters of the ohmic peeling process, specifically, the influence of salt-lye concentration combinations and field strength on time for skin cracking during ohmic peeling. We further investigated the influence of electric fields on the lye diffusivity through tomato skin. The treatments of 0.01/0.5% NaCl/NaOH at 1610 V/m and 0.01/1.0% NaCl/NaOH at 1450 V/m were the conditions that required the shortest time for cracking. For NaCl/KOH mixtures, 0.01/0.5% NaCl/KOH at 2020 V/m and 0.01/1.0% NaCl/KOH at 1450 V/m required the shortest time for cracking. Studies on diffusion through the tomato skin showed that ohmic heating significantly improved lye diffusion (p < 0.05) at both 50 and 65 °C. After an initial period, diffusivities of lye peeling with ohmic heating were greater than those without ohmic heating at both 50 and 65 °C, confirming that the electric field enhances diffusion of NaOH through the tomato skin.

Simultaneous determination of cadmium, iron and tin in canned foods using high-resolution continuum source graphite furnace atomic absorption spectrometry

A method was established to simultaneously determine cadmium, iron and tin in canned-food samples using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). The quantification step has been performed using the primary line (228.802nm) for cadmium and the adjacent secondary lines (228.725nm and 228.668nm) for iron and tin, respectively. The selected chemical modifier was an acid solution that contained a mixture of 0.1% (w/v) Pd and 0.05% (w/v) Mg. The absorbance signals were measured based on the peak area using 3 pixels for cadmium and 5 pixels for iron and tin. Under these conditions, cadmium, iron and tin have been determined in canned-food samples using the external calibration technique based on aqueous standards, where the limits of quantification were 2.10ngg−1 for cadmium, 1.95mgkg−1 for iron and 3.00mgkg−1 for tin, and the characteristic masses were 1.0pg for cadmium, 0.9ng for iron and 1.1ng for tin. The precision was evaluated using two solutions of each metal ion, and the results, which were expressed as the relative standard deviation (RSD%), were 3.4–6.8%. The method accuracy for cadmium and iron was confirmed by analyzing a certified reference material of apple leaves (NIST 1515), which was supplied by NIST. However, for tin, the accuracy was confirmed by comparing the results of the proposed method and another analytical technique (inductively coupled plasma optical emission spectrometry). The proposed procedure was applied to determine cadmium, iron and tin in canned samples of peeled tomato and sardine. Eleven samples were analyzed, and the analyte concentrations were 3.57–62.9ngg−1, 2.68–31.48mgkg−1 and 4.06–122.0mgkg−1 for cadmium, iron and tin, respectively. In all analyzed samples, the cadmium and tin contents were lower than the permissible maximum levels for these metals in canned foods in the Brazilian legislation.

Tomato peeling by ohmic heating: Effects of lye-salt combinations and post-treatments on weight loss, peeling quality and firmness

Ohmic heating without lye has shown promise in tomato peeling; however the use of lye is known to yield high peeled-product quality. This investigation was aimed at determining whether a combination of ohmic heating and low lye concentrations could be synergistic. The results indicated that 0.01/0.5% NaCl/KOH at 2020 V/m was the best condition for tomato peeling in terms of quality, weight loss, and peel cracking time. Further, the treatment showed weight loss that was not significantly different from conventional lye peeling at 7% NaOH and 7% KOH (p < 0.05). NaCl/NaOH mixtures also showed good results, but the quality of products was lower than that using the same concentration, but a higher field strength with NaCl/KOH mixtures. However, no improvement was found using NaCl/CaCl2 and NaCl/NaOH/CaCl2 mixtures which were also found difficult to use due to turbidity and cleaning difficulties. A post-peeling treatment by ohmic heating was investigated to improve firmness of ohmically peeled tomatoes. It was found that the best conditions were 2% CaCl2 solution at a field strength of 403 V/m for 1 and 5 min, and 484 V/m for 5 min. Industrial Relevance Our earlier work had shown that ohmic heating resulted in peeling of tomatoes that were immersed in salt solutions. The current work details the impact of using small concentrations of lye (either sodium or potassium hydroxide) on peeling loss and quality. Also, we investigate the potential use of calcium chloride, both as peeling solution or as a post-peeling infusion as it impacts firmness of tomatoes. We show that there are ranges of operating conditions which provide yield and quality comparable to conventional lye peeling at far lower lye concentrations, resulting in potentially significant environmental benefit to companies currently using lye peeling.

Analysis and characterization of anthocyanins and carotenoids in Japanese blue tomato.

Tomato (Solanum lycopersicum) is rich in anthocyanins, which are polyphenolic pigments. This study aimed to analyze and characterize the anthocyanin composition in cultivated blue tomato in Japan. The extracts of peel, seed, and pulp of tomatoes were purified following which anthocyanins and lycopene contents were analyzed using high-performance liquid chromatography and electrospray ionization mass spectrometry. Eleven types of anthocyanins were identified, including delphinidin, petunidin, and malvidin. Further, the antioxidant activity of anthocyanins was evaluated using 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt radical quenching assays and electron spin resonance. "Blue tomato" extracts exert antioxidant activity. Thus, we showed that petunidin was present in the "blue tomato" peel while lycopene was present in the peel and pulp. Additionally, the blue tomato peel extract was found to significantly inhibit H2O2-induced cell death in vitro. This is the first study on cell protective effects of Japanese blue tomato extract and petunidin in murine photoreceptor cells.

Utilization of By-product from Tomato Processing Industry for the Development of New Product

Extrusion cooking is recognized as a smart technology for food processors. It is a low cost, high temperature, short-time process. In this the starchy ingredients are input to create a puffed snack. However it contains multiple parameters that need to be rigorously controlled to develop an optimal process. Present study investigated the blends of corn flour, rice flour and tomato pomace (peel and seed), processed in a co-rotating twin-screw extruder and examined the effect of incorporation of tomato byproduct derivatives on final extruded product quality of the ready -to-eat expanded product. Furthermore, the physio-chemical properties, post cooking quality were analyzed for the extruded product. As tomato pomace, corn and rice flour are naturally gluten free, the extruded product would appeal to people who suffer from gluten intolerances, allergies and celiac disease. Dried and milled tomato peel and seed at levels of 0 - 30% and 0 - 5%, respectively were added to the formulation mix. D-optimal mixture design was chosen, which generated 17 combinations; within these combinations, the control formulation existed. The formulations were processed in a twin-screw extruder with a combination of parameters including: solid feed rate kept constant, water feed adjusted to 14%, screw speed of 300 rpm - 350 rpm and process temperatures 30°C to 140°C. It was observed that the addition of tomato pomace significantly increased the crude fiber content and level of protein content in the final product. The expansion ratio, hardness, colour, and overall acceptability varied significantly with respect to tomato pomace addition. Sensory test panel indicated that tomato pomace extrudate could be incorporated into ready-to-eat expanded products up to the level of 30% and it was acceptable. Optimization using D-optimal mixture design suggested that the best formulation extruded product with high desirability was the one consisting of 40% corn flour, 30% rice flour, 25% tomato peel and 5% tomato seed. The results suggest that tomato pomace can be extruded with corn and rice flour into an acceptable and highly nutritious fiber enriched snack food.