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Pomegranate (Punica granatum L.) peel lyophilized extract delays lipid oxidation in tuscan sausages

Estabilidade oxidativa de linguiça tipo Toscana com extrato liofilizado da casca de romã (Punica granatum L.)

ABSTRACT:

Pomegranate (Punica granatum L.) contains a high concentration of antioxidant and phenolic compounds. Pomegranate peel extracts at different concentrations were used as natural antioxidant to increased the lipid stability of fresh Tuscan sausages, comparing with sodium erythorbate (SE). Peels were subjected to ultrasound-assisted aqueous extraction and lyophilization. The extract was previously characterized throught phenol and flavonoids determination. The Tuscan Sausages were prepared, and color, pH, peroxides, and thiobarbituric acid reactive substances were assessed at 1, 15, and 30 days of storage, at a mean temperature of 5 ± 1 ºC and under a 12-hour light cycle/day. Sausages containing 0.05 and 0.1% of peel extract showed results similar to sodium erythorbate in lipid peroxidation. Sausages treated with pomegranate peel extracts showed an adequate global acceptability level in the sensory analysis. Pomegranate peel extracts are; therefore, a promising natural alternative for maintaining the lipid stability of Tuscan sausages, promoting the protection of the meat and in addition, being able to bring beneficial of the pomegranate to the human health.

Key words:
meat product; lipid; oxidation; storage; sensory analysis

RESUMO:

A romã (Punica granatum L.) contém uma alta concentração de compostos antioxidantes e fenólicos. Extratos de casca de romã em diferentes concentrações foram utilizados como antioxidante natural para aumentar a estabilidade lipídica de linguiça tipo Toscana, comparados ao eritorbato de sódio. As cascas foram submetidas à extração e liofilização aquosas por ultrassom. O extrato foi caracterizado por determinação de fenol e flavonóides. Os parâmetros cor, pH, peróxidos e ácido tiobarbitúrico foram avaliadas nos dias 1, 15 e 30 pós armazenamento, a temperatura de 5 ± 1 ºC e ciclo de luz de 12 horas/dia. As linguiças contendo 0,05 e 0,1% de extrato de casca apresentaram resultados semelhantes ao eritorbato de sódio quanto a peroxidação lipídica. Também apresentaram aceitabilidade global adequada na análise sensorial. Os extratos de casca de romã são, portanto, uma alternativa natural promissora para manter a estabilidade lipídica das linguiças toscanas, promovendo a proteção e podendo trazer benefícios da romã à saúde humana.

Palavras-chave:
produtos cárneos; lipídios; oxidação; armazenamento; análise sensorial

INTRODUCTION:

The use of synthetic antioxidants in foods is associated with the increase in the incidence of chronic and degenerative diseases. Therefore, researchers and the meat industry have sought alternatives to synthetic antioxidants, using natural compounds that can be produced on an industrial scale (SHIMOKOMAKI, 2006SHIMOKOMAKI, M. et al. Meat Technology News. São Paulo: Varela, 2006. 651p.).

Fresh sausages, such as Tuscan sausages, are widely accepted by consumers due to ease to prepare and consume. Lipids present in these sausages are accountable for desirable characteristics such as flavor, juiciness, nutritional value, and aroma. However, lipid oxidation can affect the quality of these products, leading to rancidification and reducing their shelf life and sensory acceptability. Oxidation can be delayed by the use of antioxidants. Quite often, synthetic antioxidants such as sodium erythorbate (SE) are used at concentrations until the desirable effect is attained (quantum satis). Nevertheless, natural antioxidants are a feasible and interesting option for increasing the shelf life of meats and their derivatives, since they promote health (JIANG & XIONG, 2016JIANG, J; XIONG, Y. L. Natural antioxidants as food and feed additives to promote health benefits and quality of meat products: A review. Meat Science , v.120, p.107-117, 2016. Available from: <Available from: http://www.sciencedirect.com/science/article/pii/S0309174016300973 >. Accessed: Dec. 12, 2016. doi: 10.1016/j.meatsci.2016.04.005.
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).

Pomegranate (Punica granatum L.) has high levels of phenolic and antioxidant compounds, and in countries whith extensive production, it is processed into juices. Nonetheless, the peels are thrown away for being regarded as industrial waste. The antioxidant and antimicrobial potential of pomegranate is distributed all over the plant (FISCHER et al., 2011FISCHER, U. A. et al. Identification and quantification of phenolic compounds from pomegranate (Punica granatum L.) peel, mesocarp, aril and differently produced juices by HPLC-DAD-ESI/MSn. Food Chemistry, v.127, p.807-821, 2011. Available from: <Available from: http://www.sciencedirect.com/science/article/pii/S0308814611000707 >. Accessed: Dec. 09, 2016. doi: 10.1016/j.foodchem.2010.12.156.
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; GONZÁLEZ-MOLINA et al., 2009GONZÁLEZ-MOLINA, E. et al. A new drink rich in healthy bioactives combining lemon and pomegranate juices. Food Chemistry, v.115, p.1364-1372, 2009. Available from: <Available from: http://www.sciencedirect.com/science/article/pii/S0308814609000983 >. Accessed: Nov. 13, 2017. doi: 10.1016/j.foodchem.2009.01.056.
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; LANSKY & NEWMAN, 2007LANSKY, E. P; NEWMAN, R. A. Punica granatum (pomegranate) and its potential for prevention and treatment of inflammation and cancer. Journal of Ethnopharmacology, v.109, p.177-206, 2007. Available from: <Available from: http://www.sciencedirect.com/science/article/pii/S0378874106004570 >. Accessed: Aug. 18, 2016. doi: 10.1016/j.jep.2006.09.006.
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; TEHRANIFAR et al., 2011TEHRANIFAR, A. et al. High potential of agro-industrial by-products of pomegranate (Punica granatum L.) as the powerful antifungal and antioxidant substances. Industrial Crops And Products, v.34, p.1523-1527, 2011. Available from: <Available from: http://www.sciencedirect.com/science/article/pii/S0926669011001415 >. Accessed: Apr. 12, 2017. doi: 10.1016/j.indcrop.2011.05.007.
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), but the peel contains higher amounts of nutritional and bioactive compounds when compared to edible parts and to other fruits (ORGIL et al., 2014ORGIL, O. et al. The antioxidative and anti-proliferative potential of non-edible organs of the pomegranate fruit and tree. Lwt - Food Science and Technology, v.58, p.571-577, 2014. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0023643814001807 >. Accessed: Jan, 22, 2018. doi: 10.1016/j.lwt.2014.03.030.
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; SESTILI et al., 2007SESTILI, P. et al. Cytoprotective effect of preparations from various parts of Punica granatum L. fruits in oxidativel y injured mammalian cells in comparison with their antioxidant capacity in cell free systems. Pharmacological Research, v.56, p.18-26, 2007. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S1043661807000485 >. Accessed: Sep. 24, 2017. doi: 10.1016/j.phrs.2007.02.003.
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), indicating the potential use of this raw material in the pharmaceutical, cosmetic, and food industries (AMYRGIALAKI et al., 2014AMYRGIALAKI, E. et al. Optimization of the extraction of pomegranate (Punica granatum) husk phenolics using water/ethanol solvent systems and response surface methodology. Industrial Crops and Products, v.59, p.216-222, 2014. Available from: <Available from: http://www.sciencedirect.com/science/article/pii/S0926669014002763 >. Accessed: Aug. 01, 2016. doi: 10.1016/j.indcrop.2014.05.011.
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).

This research aimed to produce Tuscan sausages using pomegranate peel lyophilized extract (PPLE) and to assess the potential of this natural antioxidant for delaying lipid oxidation reactions and providing (or not) good sensory properties during storage.

MATERIALS AND METHODS:

Preparation of pomegranate peel extracts

Pomegranates (Punica granatum L) were purchased in the local market in Getúlio Vargas, Rio Grande do Sul State, Brazil, in July 2017. The fruits were washed in drinkable water and immersed in sodium hypochlorite (2.5%) for 15 minutes, weighed whole, and sorted into peel, pulp, and seeds for yield estimation. The peels were cut into 3-cm slices and dried at 40±5 ºC for 72 hours in an air circulating oven (Splabor, M- SPL 102). Peels were weighed again and ground in a cyclone mill (Marconi, MA-020) with a 20-mesh sieve, and the resultant powder was stored in a hermetically sealed container at room temperature until analysis.

The phenolic compounds, were extracted by an ultrasonic-assisted method (NIN - 001-13, SB5200 DTDN - UltrasonicCleaner) at 40 KHz and at a maximum temperature of 40 ºC for 2 hours obtaining the pomegranate peel aqueous extract (PPAE). Thereafter, the PPAE was frozen (-70 ºC ± 10 ºC) for 24 hours in an ultra freezer (ColdLab, CL 600-80) for lyophilization (Terroni, model LS3000) for 26 hours, and the resultant product was the pomegranate peel lyophilized extracts (PPLE). PPAE and PPLE were stored at -20 °C in a hermetically sealed container protected from light.

Characterization of the extracts

Total phenols of PPAE and PPLE were quantified by the Folin-Ciocalteau’s method (ROESLER et al., 2007ROESLER, R. et al. Antioxidant activity of cerrado fruits. Food Science and Technology, v.27, p.53-60, 2007. Available from: <Available from: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-20612007000100010&lng=pt&nrm=iso&tlng=pt >. Accessed: Jun, 13, 2017. doi: 10.1590/s0101-20612007000100010.
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), expressed as mg of gallic acid equivalent (GAE)/g of extract. Absorbance was measured by a spectrophotometer (Shimadzu, model UV-1800) at 760 nm. Total flavonoids were quantified by the AlCl3- complexation method (ZHISHEN et al., 1999ZHISHEN, J. et al. The determination of flavonoid contents in mulberry and their scavenging effects on superoxide radicals. Food Chemistry, v.64, p.555-559, 1999. Available from: <Available from: https://www-sciencedirect.ez116.periodicos.capes.gov.br/science/article/pii/S0308814698001022 >. Accessed: Apr. 13, 2017. doi: 10.1016/S0308-8146(98)00102-2.
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). Results were expressed as catechin equivalents (mg of CATE/g) and absorbance was read at 510 nm. Antioxidant activity was assessed by 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical sequestering ability (ROESLER et al., 2007ROESLER, R. et al. Antioxidant activity of cerrado fruits. Food Science and Technology, v.27, p.53-60, 2007. Available from: <Available from: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-20612007000100010&lng=pt&nrm=iso&tlng=pt >. Accessed: Jun, 13, 2017. doi: 10.1590/s0101-20612007000100010.
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) and results were expressed as µmol of Trolox equivalent/mg of sample. The samples were read at 510 nm.

Manufacturing process of Tuscan sausages containing pomegranate peel extracts (Table 1)

Table 1
Tuscan sausage formulations at 1000 g yield, containing three freeze-dried pomegranate peel extracts (PPLE) at different concentrations (PPLE1 - 0.025%; PPLE2 - 0.05%; PPLE3 - 0.1%), compared to control formulation that has only sodium erythorbate (SE).

The manufacture of Tuscan sausages followed the Technical Regulation on Identity and Quality established by Normative Rule n°4 (BRASIL, 2000BRASIL (Ministério Da Agricultura e do Abastecimento Secretaria de Defesa Agropecuária). Instrução Normativa N° 04. Publicação em 31 de março de 2000.2000. Available from: <Available from: http://www.agais.com/normas/carne/carnes_linguica.htm >. Accessed: Jan. 18, 2018.
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). Raw materials were obtained from pigs slaughtered at a locally inspected abattoir, in compliance with hygiene and sanitation standards and with the recommended slaughtering technology. After chilling at 7 ºC (±1 ºC) for 12 hours, the carcasses were deboned and the pork shoulder, leg, and belly were removed for the production of meat mixes. Three PPLE concentrations (0.025, 0.05, and 0.1%) and SE (0.025%) were used as antioxidant for the treatments. The sausages were vacuum packed into portions (± 120 grams) and stored at 5±1 ºC under an artificial white light source with a luminous flux of 415 lumens, controlled by a programmable analog timer, for 12 hours/day, simulating a gondola shelf.

Physicochemical analysis

The centesimal composition of elaborated sausages was evaluated according to Lutz (2008) and the formulated products were in accordance with the Normative Instruction (BRASIL, 2000BRASIL (Ministério Da Agricultura e do Abastecimento Secretaria de Defesa Agropecuária). Instrução Normativa N° 04. Publicação em 31 de março de 2000.2000. Available from: <Available from: http://www.agais.com/normas/carne/carnes_linguica.htm >. Accessed: Jan. 18, 2018.
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). Samples were assessed at 1, 15, and 30 days, in triplicate, as to pH, color, peroxide levels, and thiobarbituric acid reactive substances (TBARS). The pH was measured by drilling in different points of the sausage, performed in triplicate and with the aid of calibrated pHmetro (Metrohm - 826 mobile). Color was evaluated by reflectance using a colorimeter (Minolta, model CR-400) and luminosity L*, a* (red-green), and b* (yellow-blue). Peroxide levels were determined as proposed by INSTITUTO ADOLFO LUTZ (2008)INSTITUTO ADOLFO LUTZ. Métodos químicos e físicos para análise de alimentos. 1.ed. São Paulo, 2008, p.1020. and the results were expressed as mEq/kg of sample. The TBARS was estimated by the spectrophotometric method described by VYNCKE (1970VYNCKE, W. Direct determination of the thiobarbituric acid value in trichloracetic acid extracts of fish as a measure of oxidative rancidity. Fette, Seifen, Anstrichmittel, v.72, p.1084-1087, 1970. Available from: <Available from: http://onlinelibrary.wiley.com/doi/10.1002/lipi.19700721218/abstract >. Accessed: Jun, 11, 2017. doi: 10.1002/lipi.19700721218/abstract.
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) and adapted by MARANGONI & MOURA (2011MARANGONI, C.; MOURA, N. F. D. Antioxidant activity of essential oil from Coriandrum Sativum L. in Italian salami. Ciência e Tecnologia de Alimentos, v.31, p.124-128, 2011. Available from: <Available from: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-20612011000100017 >. Accessed: Mar, 15, 2017. doi: 10.1590/s0101-20612011000100017.
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), and the results were expressed as mg of malonaldehyde/kg of sample.

Consumer testing

The PPLE3 (0.1%) and sodium erythorbate (SE 0.025%) treatments were subjected to sensory analysis at 28 days after sausage manufacture using the triangle and affective sensory tests applied to 53 panelists (taste testers). The panelists were previously given instructions on how to conduct the analyses and signed a free informed consent form, meeting the principles of the Research Ethics Committee of Universidade de Passo Fundo (UPF), process no. 63579517.6.0000.5342.

Statistical analysis

Results of the physicochemical analysis of sausages were analyzed using the mean and standard deviation of triplicates and statistically treated by analysis of variance ANOVA (with normality test) and Tukey test at 5% significance (P>0, 05) using the SPSS Statistics software (version 23). For the statistical representation of the results of the sensory analysis the nonparametric Mann-Whitney test was used.

RESULTS AND DISCUSSION:

Yield and characterization of extracts

PPLE had a yield of 0.78% compared to the initial fruit mass and of 18.96% compared to the crude peel powder. PPAE contained 66.14 mg of GAE/g of extract of total polyphenols and 6.84 mg of CATE/g of extract of total flavonoids. The rate of inhibition of the DPPH radical was 91.70% for the extract at the concentration of 100 mg/mL, equivalent to 3.39 µmol of Trolox equivalent/mg of sample. PPLE contained 89.52 mg of GAE/g and 12.05 mg of CATE/g of extract of polyphenols and flavonoids; respectively, and the rate of inhibition in the DPPH assay was 90.21% for the extract at the concentration of 100 mg/mL, equivalent to 3.34 µmol of Trolox equivalent/mg of sample.

No difference was observed in antioxidant potential between PPAE and PPLE. However, PPLE showed higher total polyphenol (35.35%) and total flavonoid (76.16%) levels than PPAE, indicating that this processing technique may increase the concentrations of active compounds, also showing the potential use of pomegranate peel extract as a source of bioactive compounds and natural antioxidants. Other authors have reported values of total polyphenol content which ranged between 42.16 and 320.26 mg GAE/g in pomegranate peel (DIAMANTI et al. , 2017DIAMANTI, A. C. et al. Green extraction of polyphenols from whole pomegranate fruit using cyclodextrins. Food Chemistry, v.214, p.61-66, 2017. Available from: <Available from: http://www.sciencedirect.com/science/article/pii/S0308814616310949 >. Accessed: May, 13, 2017. doi: 10.1016/j.foodchem.2016.07.072.
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; ELFALLEH et al., 2009ELFALLEH, W. et al. Physico-chemical properties and DPPH-ABTS scavenging activity of some local pomegranate (Punica granatum) ecotypes. International Journal of Food Sciences and Nutrition, v.60, p.197-210, 2009. Available from: <Available from: https://www.ncbi.nlm.nih.gov/pubmed/19629823 >. Accessed: Oct, 03, 2017. doi: 10.1080/09637480903067037.
https://www.ncbi.nlm.nih.gov/pubmed/1962...
; GALAZ et al., 2017GALAZ, P. et al. Effect of drum drying temperature on drying kinetic and polyphenol contents in pomegranate peel. Journal Of Food Engineering, v.208, p.19-27, 2017. Available from: <Available from: http://www.sciencedirect.com/science/article/pii/S0260877417301425 >. Accessed: May, 15, 2017. doi: 10.1016/j.jfoodeng.2017.04.002.
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; HASNAOUI et al., 2014HASNAOUI, N. et al. Valorization of pomegranate peel from 12 cultivars: Dietary fibre composition, antioxidant capacity and functional properties. Food Chemistry, v.160, p.196-203, 2014. Available from: <Available from: http://www.sciencedirect.com/science/article/pii/S0308814614004804 >. Accessed: May, 09, 2017. doi: 10.1016/j.foodchem.2014.03.089.
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; KAZEMI et al., 2016KAZEMI, M. et al. Optimization of pulsed ultrasound-assisted technique for extraction of phenolics from pomegranate peel of Malas variety: Punicalagin and hydroxybenzoic acids. Food Chemistry, v.206, p.156-166, 2016. Available from: <Available from: https://www.ncbi.nlm.nih.gov/pubmed/15615428 >. Accessed: May, 03, 2017. doi: 10.1016/j.foodchem.2016.03.017.
https://www.ncbi.nlm.nih.gov/pubmed/1561...
; LI et al., 2006LI, Y et al. Evaluation of antioxidant properties of pomegranate peel extract in comparison with pomegranate pulp extract. Food Chemistry, v.96, p.254-260, 2006. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0308814605001780 >. Accessed: Oct. 21, 2017. doi: 10.1016/j.foodchem.2005.02.033.
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; MORSY et al., 2018MORSY, M. K. et al. Impact of pomegranate peel nanoparticles on quality attributes of meatballs during refrigerated storage. Lwt Food Science and Technology, v.89, p.489-495, 2018. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0023643817308411 >. Accessed: Jan, 12, 2018. doi: 10.1016/j.lwt.2017.11.022.
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). In processed goat meat products, the antioxidant effect of pomegranate peel extract was higher than those reported in citric fruit peel extracts and of seed powder described by DEVATKAL et al. (2010DEVATKAL, S. K. et al. Anti-oxidant effect of extracts of kinnow rind, pomegranate rind and seed powders in cooked goat meat patties. Meat Science , v.85, p.155-159, 2010. Available from: <Available from: http://www.sciencedirect.com/science/article/pii/S0309174009003994 >. Accessed: May, 21, 2017. doi: 10.1016/j.meatsci.2009.12.019.
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).

The antioxidant capacity of pomegranate peel was described by FISCHER et al. (2011FISCHER, U. A. et al. Identification and quantification of phenolic compounds from pomegranate (Punica granatum L.) peel, mesocarp, aril and differently produced juices by HPLC-DAD-ESI/MSn. Food Chemistry, v.127, p.807-821, 2011. Available from: <Available from: http://www.sciencedirect.com/science/article/pii/S0308814611000707 >. Accessed: Dec. 09, 2016. doi: 10.1016/j.foodchem.2010.12.156.
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), who mention that variations in such capacity could be related to extraction methods, solvents used, and time and temperature of protocols. Water, as extracting solvent, precludes the need for later purifications and possible risks associated with the use of the extracts in foods. Factors such as fruit cultivar, fertilization, soil, climate, sun exposure, maturation stage, among others, can also be held accountable for the differences in results.

Characterization of Tuscan sausages containing PPLE and SE

The influence of PPLE on pH of Tuscan sausages during refrigerated storage is shown in table 2. The results obtained depended on the storage time, mean pH values ranged from 5.66 to 6.16”. Treatments were similar in terms of pH (P>0.05). However, when compared on the 1st day of storage, statistical significance of PPLE3 was higher (P<0.05) than those reported in the control (SE), which occurred again on the 15th day. The pH in the 6.2-5.7 range were observed by SALEH et al. (2017SALEH, E. A. et al. Effect of pomegranate peel powder on the hygienic quality of beef sausage. Journal of Microbiology, Biotechnology And Food Sciences, v.6, p.1300-1304, 2017. Slovak University of Agriculture in Nitra. Available from: <Available from: https://www.researchgate.net/publication/317579028_Effect_of_pomegranate_peel_powder_on_the_hygienic_quality_of_beef_sausage >. Accessed: Dec, 02, 2017. doi: 10.15414/jmbfs.2017.6.6.1300-1304.
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) when used pomegranate peel powder in their meat sausages.

Table 2
pH of Tuscan sausages according to storage time and treatments.

The gradual decrease in pH can be attributed to storage temperature (5 ºC ± 1) and reduction of oxygen content, brought about by vacuum packing, leading to slower glycogen degradation and lactic acid formation, as well as to homogenization of meat mixes and standardization, which renders sausages less susceptible to pH changes. The pH changes are more commonly observed in cured and aged emulsified meat products, affecting their quality and shelf-life.

In emulsified products with addition of pomegranate peel powder, pH ranged from 6.27 and 5.73 (SALEH et al., 2017SALEH, E. A. et al. Effect of pomegranate peel powder on the hygienic quality of beef sausage. Journal of Microbiology, Biotechnology And Food Sciences, v.6, p.1300-1304, 2017. Slovak University of Agriculture in Nitra. Available from: <Available from: https://www.researchgate.net/publication/317579028_Effect_of_pomegranate_peel_powder_on_the_hygienic_quality_of_beef_sausage >. Accessed: Dec, 02, 2017. doi: 10.15414/jmbfs.2017.6.6.1300-1304.
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), with no significant differences in pH (P>0.05) during storage (EL-NASHI et al., 2015EL-NASHI, H. B. et al. Quality characteristics of beef sausage containing pomegranate peels during refrigerated storage. Annals Of Agricultural Sciences, v.60, p.403-412, 2015. Available from: <Available from: http://www.sciencedirect.com/science/article/pii/S0570178315000378 >. Accessed: Aug. 14, 2016. doi: 10.1016/j.aoas.2015.10.002.
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). QIN et al. (2013QIN, Y. Y. et al. Antioxidant effect of pomegranate rind powder extract, pomegranate juice, and pomegranate seed powder extract as antioxidants in raw ground pork meat. Food Science And Biotechnology, v.22, p.1063-1069, 2013. Available from: <Available from: https://link.springer.com/content/pdf/10.1007/s10068-013-0184-8.pdf >. Accessed: Dec. 18, 2017. doi: 10.1007/s10068-013-0184-8.
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) observed a decrease in pH from 5.88 to 5.61 after addition of pomegranate peel powder in pork, but no significant difference in pH in breaded chicken cutlets with addition of pomegranate juice extract (NAVEENA et al., 2008NAVEENA, B. M. et al. Comparative efficacy of pomegranate juice, pomegranate rind powder extract and BHT as antioxidants in cooked chicken patties. Meat Science , v.80, p.1304-1308, 2008. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0309174008002064 >. Accessed: Nov. 09, 2017. doi: 10.1016/j.meatsci.2008.06.005.
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).

In color analysis, PPLE treatments showed difference (P<0.05) in luminosity L* when compared with each other and with the control at the beginning of the storage period (Figure 1). PPLE2 and PPLE3 treatments did not reveal any differences (P>0.05) at 15 and 30 days, whereas PPLE1 was similar to the control at 30 days. ESTÉVEZ & CAVA (2004ESTÉVEZ, M.; CAVA, R. Lipid and protein oxidation, release of iron from heme molecule and colour deterioration during refrigerated storage of liver pâté. Meat Science , v.68, p.551-558, 2004. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0309174004001317 >. Accessed: Nov, 12, 2017. doi: 10.1016/j.meatsci.2004.05.007.
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) reported that the L* value increased in sausages stored for 60 days without addition of rosemary extracts. ESTÉVEZ et al., 2005ESTÉVEZ, M. Protein oxidation in Frankfurters with increasing levels of Added Rosemary Essential Oil: Effect on Color and Texture Deterioration. Food Chemistry and Toxicology, v.70, n.7, 2005. Available from: <Available from: https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1365-2621.2005.tb11464.x >. Accessed: Nov, 11, 2019. doi: 10.1111/j.1365-2621.2005.tb11464.x.
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) used rosemary essential oil to verify the protein oxidation of meat products, proving that the addition of antioxidants (300 and 600 ppm) in the product reduces color changes when compared to the control product.

Figure 1 -
Behavior of color parameters during the storage of Tuscan sausages. PPLE: Pomegranate peel lyophilized extracts; SE: sodium erythorbate. *Mean ± (standard deviation) was performed in the formulations with respect to storage time. Each line has three times, when the letters of the same line are different, there was significance. *Tukey test (P>0.05) was performed between formulations (each line color represents one formulation). When the letter is different between the formulations, there was significance.

The stability exhibited by PPLE2 and PPLE3 for a* were the same at 30 days, without however maintaining the levels of the SE treatment for the red color of sausages. Color of emulsified meat products is maintained, in many cases, by the use of dyes. No dyes were used in the present study, since the aim was to assess nothing but the effects of SE and PPLE on color attributes. In color parameter b*, treatments had different behaviors during shelf life, with no differences (P>0.05) between PPLE2 and PPLE3 at 15 and 30 days.

DEVATKAL et al. (2010DEVATKAL, S. K.; NAVEENA, B. M. Effect of salt, kinnow and pomegranate fruit by-product powders on color and oxidative stability of raw ground goat meat during refrigerated storage. Meat Science , v.85, p.306-311, 2010. Available from: <Available from: https://www-sciencedirect.ez116.periodicos.capes.gov.br/science/article/pii/S0309174010000227#bib13 >. Accessed: Nov, 19, 2019. doi: 10.1016/j.meatsci.2010.01.019.
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) evaluated the use of pomegranate and bergamot antioxidants in goat meat hamburgers during storage (4 ± 1 °C) in different packaging methods. The vacuum and 1% concentration of pomegranate peel extract resulted in greater color stability when compared to treatments such as modified atmosphere.

DEVATKAL & NAVEENA, (2010DEVATKAL, S. K.; NAVEENA, B. M. Effect of salt, kinnow and pomegranate fruit by-product powders on color and oxidative stability of raw ground goat meat during refrigerated storage. Meat Science , v.85, p.306-311, 2010. Available from: <Available from: https://www-sciencedirect.ez116.periodicos.capes.gov.br/science/article/pii/S0309174010000227#bib13 >. Accessed: Nov, 19, 2019. doi: 10.1016/j.meatsci.2010.01.019.
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), conducted a five-treatment study evaluating the color and oxidative stability of raw ground goat meat stored at 4 ± 1 °C. The comparison between: control sample (meat only), salted meat, salted meat and pomegranate peel powder, salted meat and pomegranate peel, salted meat and pomegranate seeds, with pomegranate added samples, those with the highest antioxidant effect and the best color.

The discoloration in meat products increased when the products are displayed in illuminated counters at the point of sale, where this study was simulated, this is due to the dissociation of heme nitric oxide.

There was no significant difference (P>0.05) in peroxide levels between treatments on the 1st day (Figure 2). However, there was some difference at 15 days in PPLE3 (P<0.05) when compared to the other treatments, with the lowest peroxide levels (4.91±0.45), whereas PPLE1 had the highest levels (10.16±0.21) at 30 days. At the end of the shelf life, PPLE2 and PPLE3 showed no differences (P>0.05) when compared to the control (Figure 2). There was a significant increase (P<0.05) in all treatments at 15 days, with the maximum of 10.16 mEq/kg in the PPLE1 at 30 days. This increase is believed to be more associated with the quick formation of peroxides during storage than with the degradation of peroxides into secondary oxidation products (BAZARGANI-GILANI et al., 2015BAZARGANI-GILANI, B. et al. Effect of pomegranate juice dipping and chitosan coating enriched with Zataria multiflora Boiss essential oil on the shelf-life of chicken meat during refrigerated storage. Innovative Food Science & Emerging Technologies, v.29, p.280-287, 2015. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S1466856415000752 >. Accessed: Jan. 15, 2018. doi: 10.1016/j.ifset.2015.04.007.
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).

Figure 2 -
Peroxide (A) and T BARS (B) levels during the storage of Tuscan sausages. PPLE: Pomegranate peel lyophilized extracts; SE: sodium erythorbate. *Mean ± (standard deviation) was performed in the formulations with respect to storage time. Each line has three times, when the letters of the same line are different, there was significance. *Tukey test (p>0.05) was performed between formulations (each line color represents one formulation). When the letter is different between the formulations, there was significance.

The TBARS is also indicated to assess lipid oxidation, as this analysis quantifies the levels of malonaldehyde (MDA), one of the main by-products of the degradation of poly-unsaturated fatty acid hydroperoxides, formed during oxidation. No significant difference (P>0.05) was observed in TBARS levels in PPLE2 and PPLE3 on the first day of storage (Figure 2). The increase in PPLE concentrations (P<0.05) might have improved the capacity to eliminate radicals involved in lipid peroxidation, when compared to SE, as suggested by authors like NAVEENA et al. (2008NAVEENA, B. M. et al. Comparative efficacy of pomegranate juice, pomegranate rind powder extract and BHT as antioxidants in cooked chicken patties. Meat Science , v.80, p.1304-1308, 2008. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0309174008002064 >. Accessed: Nov. 09, 2017. doi: 10.1016/j.meatsci.2008.06.005.
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) and NEGI et al. (2003NEGI, P. S. et al. Antioxidant and antimutagenic activities of pomegranate peel extracts. Food Chemistry, v.80, p.393-397, 2003. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0308814602002790 >. Accessed: Dec. 23, 2017. doi: 10.1016/s0308-8146(02)00279-0.
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). On the first day, TBARS levels were equal or close to 0.1 mg of MDA/kg in all treatments, which was observed by ALMEIDA et al. (2015ALMEIDA, P. L. D. et al. Effect of jabuticaba peel extract on lipid oxidation, microbial stability and sensory properties of Bologna-type sausages during refrigerated storage. Meat Science, v.110, p.9-14, 2015. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0309174015300401 >. Accessed: Jan. 27, 2018. doi: 10.1016/j.meatsci.2015.06.012.
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) and KIM et al. (2014KIM, H. W. at al. Effects of kimchi and smoking on quality characteristics and shelf life of cooked sausages prepared with irradiated pork. Meat Science , v.96, p.548-553, 2014. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0309174013005081 >. Accessed: Jan, 17, 2018. doi: 10.1016/j.meatsci.2013.08.023.
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) in meat products. These levels often go up when the storage of meat products is extended, reaching a maximum value and decreasing thereafter due to additional reactions of MDA with amine groups (CHANNON & TROUT, 2002CHANNON, H. A.; TROUT, G. R. Effect of tocopherol concentration on rancidity development during frozen storage of a cured and an uncured processed pork product. Meat Science , v.62, p.9-17, 2002. Available from: <Available from: http://www.sciencedirect.com/science/article/pii/S0309174001002212 >. Accessed: Abr. 17, 2017. doi: 10.1016/s0309-1740(01)00221-2.
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).

Inhibitory effects of PPLE are attributed to its phenolic compounds, which participate in the oxidation process by blocking the free radical chain reactions (NEGI et al., 2003NEGI, P. S. et al. Antioxidant and antimutagenic activities of pomegranate peel extracts. Food Chemistry, v.80, p.393-397, 2003. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0308814602002790 >. Accessed: Dec. 23, 2017. doi: 10.1016/s0308-8146(02)00279-0.
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). There was a decrease in TBARS probably because the action of antioxidants lasts more than 30 days of shelf life in fresh sausages manufactured and stored under the conditions used in this study. The level of perception of rancid odors by trained and untrained panelists ranges from 0.5 to 2.0 mg of MDA/kg of sample (ALMEIDA et al., 2015ALMEIDA, P. L. D. et al. Effect of jabuticaba peel extract on lipid oxidation, microbial stability and sensory properties of Bologna-type sausages during refrigerated storage. Meat Science, v.110, p.9-14, 2015. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0309174015300401 >. Accessed: Jan. 27, 2018. doi: 10.1016/j.meatsci.2015.06.012.
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; GATELLIER et al., 2017GATELLIER, P. Use of a fluorescence front face technique for measurement of lipid oxidation during refrigerated storage of chicken meat. Meat Science , v.76, p.543-547, 2017. Available from: <Available from: http://www.sciencedirect.com/science/article/pii/S0309174007000241?via=ihub >. Accessed: Nov. 13, 2017. doi: 10.1016/j.meatsci.2007.01.006.
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; TRINDADE et al., 2009TRINDADE, M. P. et al. Antimicrobial activity of pomegranate (Punica granatum) peel tincture on Staphylococcus aureus and Streptococcus pyogenes strains: an in vitro study. Brazilian Journal of Health Research, v.11, p.49-54, 2009. Available from: <Available from: http://periodicos.ufes.br/RBPS/article/view/355/266 >. Accessed: Aug, 22, 2017. doi: 10.21722/rbps.v0i0.355.
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). The values reported for Tuscan sausages with PPLE and SE were lower than 0.5 mg of MDA/kg and; therefore, imperceptible when stored under refrigeration (5±1 ºC) for 30 days. QIN et al. (2013QIN, Y. Y. et al. Antioxidant effect of pomegranate rind powder extract, pomegranate juice, and pomegranate seed powder extract as antioxidants in raw ground pork meat. Food Science And Biotechnology, v.22, p.1063-1069, 2013. Available from: <Available from: https://link.springer.com/content/pdf/10.1007/s10068-013-0184-8.pdf >. Accessed: Dec. 18, 2017. doi: 10.1007/s10068-013-0184-8.
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) described TBARS levels between 0.41 and 1.07 mg of MDA/kg up to 12 days of storage using pomegranate juice and peel powder in ground pork. NAVEENA et al. (2008NAVEENA, B. M. et al. Comparative efficacy of pomegranate juice, pomegranate rind powder extract and BHT as antioxidants in cooked chicken patties. Meat Science , v.80, p.1304-1308, 2008. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0309174008002064 >. Accessed: Nov. 09, 2017. doi: 10.1016/j.meatsci.2008.06.005.
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) considered pomegranate peel extract to be an efficient antioxidant for chicken meat, delaying oxidative rancidity.

In some cases, in the absence of TBA, acid extracts can have peak absorbance at 532 nm, leading to overestimation of lipid extension by TBARS (GANHÃO et al., 2011GANHÃO, R. et al. Suitability of the TBA method for assessing lipid oxidation in a meat system with added phenolic-rich materials. Food Chemistry, v.126, p.772-778, 2011. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0308814610014822 >. Accessed: Dec. 12, 2017. doi: 10.1016/j.foodchem.2010.11.064.
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). This was evident with the value obtained for PPLE2 at 15 days. These results should be viewed with caution, since the reaction to TBARS is not specific to MDA, given that other compounds can also react with the acid (FIGUEIRÊDO et al., 2014FIGUEIRÊDO, B. C. Effect of annatto powder and sodium erythorbate on lipid oxidation in pork loin during frozen storage. Food Research International, v.65, p.137-143, 2014. Available from: <Available from: http://www.sciencedirect.com/science/article/pii/S0963996914004931 >. Accessed: Dec. 08, 2016. doi: 10.1016/j.foodres.2014.07.016.
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).

Sensory analysis

In the triangle sensory analysis, 56.6% of panelists did not detect differences (P>0.05) between the sausages containing control (SE) or PPLE3. The levels of acceptance did not differ (P>0.05) according to the Mann-Whitney test for the assessed parameters. It was not possible to detect unpleasant flavor, signs of rancidity, or astringent taste that could lead panelists to reject the samples. These values are represented on an interval between 7 (like moderately) and 8 (like very much), as shown in figure 3.

Figure 3
- Hedonic scale showing the acceptability test for fresh sausage containing PPLE and SE. PPLE: Pomegranate peel lyophilized extracts; SE: sodium erythorbate. The attributes color, texture, flavor and overall acceptability of the control formulation and the extract formulation were evaluated by sensory analysis, acceptability and classified by hedonic scale: 1-Dislike extremely; 2-Dislike very much; 3-Dislike moderately; 4-Dislike lightly; 5-Neither like or dislike; 6-Like slightly; 7- Like moderately; 8-Like very much; 9-Like extremely. The figureshows the amount of test that obtained the hedonic scale grade in relation to the formulations.

Sausages treated with PPLE3 and SE were equally accepted, in line with ALMEIDA et al. (2015ALMEIDA, P. L. D. et al. Effect of jabuticaba peel extract on lipid oxidation, microbial stability and sensory properties of Bologna-type sausages during refrigerated storage. Meat Science, v.110, p.9-14, 2015. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0309174015300401 >. Accessed: Jan. 27, 2018. doi: 10.1016/j.meatsci.2015.06.012.
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) and DEVATKAL et al. (2010DEVATKAL, S. K.; NAVEENA, B. M. Effect of salt, kinnow and pomegranate fruit by-product powders on color and oxidative stability of raw ground goat meat during refrigerated storage. Meat Science , v.85, p.306-311, 2010. Available from: <Available from: https://www-sciencedirect.ez116.periodicos.capes.gov.br/science/article/pii/S0309174010000227#bib13 >. Accessed: Nov, 19, 2019. doi: 10.1016/j.meatsci.2010.01.019.
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). Acceptability was satisfactory in terms of color, with mean scores of 7.56 and 7.26 for PPLE3 and SE, respectively. Regarding global acceptability, the highest mean was 7.56 for PPLE3 and 7.47 for ES, whose evaluation on the hedonic scale was between “like moderately” and “like very much” indicating that the addition of PPLE to Tuscan sausages presente good sensory parameters, when compared to the control, supporting its use as natural antioxidant in this meat product.

CONCLUSION:

PPLE delayed lipid oxidation and proved to be better than or similar to SE. Lipid changes were not significant at 30 days, demonstrating stability of the manufactured Tuscan sausages. The extract was able to decrease lipid oxidation, confirming global sustainability because of the use of an agroindustrial residue (pomegranate peel). Sausages prepared with the peel extract showed good acceptability.

ACKNOWLEDGEMENTS

Was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Brasil - Finance code 88881.121063/2016-01 (Post Doctoral Scholarship).

REFERENCES

  • CR-2019-0698.R1

Publication Dates

  • Publication in this collection
    06 Apr 2020
  • Date of issue
    2020

History

  • Received
    09 Sept 2019
  • Accepted
    03 Jan 2020
  • Reviewed
    24 Feb 2020
Universidade Federal de Santa Maria Universidade Federal de Santa Maria, Centro de Ciências Rurais , 97105-900 Santa Maria RS Brazil , Tel.: +55 55 3220-8698 , Fax: +55 55 3220-8695 - Santa Maria - RS - Brazil
E-mail: cienciarural@mail.ufsm.br