QUALITY OF COMMERCIAL GROUND PAPRIKA AND ITS OLEORESINS

Transcription

1 QUALITY OF COMMERCIAL GROUND PAPRIKA AND ITS OLEORESINS Aleksandra N. Tepić, Gordana R. Dimić, Biserka L. Vujičić, Žarko S. Kevrešan, Marika Varga and Zdravko M. Šumić Spices are widely used in food processing. One of the main disadvantages of spices application is their frequent microbiological spoilage. Health benefits (microbiological status, mineral and heavy metal content) of commercial ground paprika (Capsicum annuum), as well as the colour and microbiological status of its conventional and supercritical oleoresins were examined in this work. KEYWORDS: ground paprika, mineral content, heavy metals content, extraction, oleoresin, ASTA. INTRODUCTION Paprika varieties differ by its colour, shape, dimension, flavour, degree of hotness, etc. Paprika is often consumed as fresh fruit or dried and used as ground in the food industry, but it is also used in pharmaceutical and cosmetic industries. Spice pepper (Capsicum annuum) takes the very special place among paprika varieties. Its agricultural breeding is aimed to production of ground paprika. Colour of ground paprika represents its main quality attribute. More than 20 different pigments from paprika fruits have been identified (1, 2, 3): green chlorophylls, yellowishorange lutein, zeaxanthin, violaxanthin, antheraxanthin, β-cryptoxanthin and β-carotene. Red capsanthin, capsorubin and cryptoxanthin are characteristic exclusively for the genus Capsicum and are the main pigments that determine the colour of red pepper. β-, α-, γ- carotene and β-cryptoxanthin have provitamin activity. A number of investigations revealed that carotenoid rich diet lowers the risk from some degenerative disorders, including different kinds of cancer, cardiovascular and ophthamologic disorders (4, 5). Red paprika is a fruit rich in antioxidants (6-9). Ground paprika is a spice prone to microbial spoilage. Its extracts are widely used in the food industry. Capsicum oleoresins from paprika contain a complex mixture of essen- Assist. Aleksandra N. Tepić, M.Sc., tepical@uns.ns.ac.yu, Dr. Gordana R. Dimić, Assoc. Prof., Dr. Biserka L. Vujičić, Prof., Marika Varga, M.Sc., Zdravko M. Šumić, B.Sc., Faculty of Technology, Bulevar Cara Lazara 1, Novi Sad, Žarko S. Kevrešan, M.Sc., Food Institute, Bulevar Cara Lazara 1, Novi Sad, Serbia 77

2 tial oils, waxes, coloured materials, and several capsaicinoids. They also contain resin acids and their esters, terpenes, and oxidation or polymerization products of these terpenes (10). Due to their aroma, flavour, taste and colour, they can completely substitute ground paprika in products, in order to improve sensory properties of food products. Ground paprika extracts can be produced by conventional (Soxhlet extraction, using organic solvents) or supercritical fluid extraction (usually by the use of carbon-dioxide as supercritical solvent). The most important advantages of Soxhlet extraction are: the sample is all the time in contact with fresh solvent, it is a very simple methodology with the possibility to extract more sample mass than most of the extraction methods (microwaveextraction, supercritical fluids, etc.). However, there are some disadvantages of this method: long time of extraction, large solvent waste (which implies some economical and environmental problems), relatively high working temperature, as the samples are extracted at the boiling point of the solvent, so thermal decomposition of some compounds can occur. Moreover, after the removal of solvent (in vacuum), some residues remain in the extract. On the other hand, supercritical carbon-dioxide extraction requires shorter time, smaller amount of solvent, CO 2 is inflammable, chemically inert and less toxic, and there is no need for solvent removal, and the extract is solvent-free (11). The aim of this work was to determine the differences in extractable colur and microbiological status between ground paprika, conventional and supercritical oleoresins, as well as to investigate the health benefits of commercial ground paprika. EXPERIMENTAL Ground paprika used in this experiment was purchased in a supermarket. Soxhlet extraction was performed to the complete discolouration, using technical grade hexane as solvent (12). The solvent was removed after extraction using vacuum evaporator. Supercritical CO 2 extraction (SC-CO 2 ) was carried out with technical carbon-dioxide (Tehno-gas, Novi Sad, Serbia) using a laboratory-scale high-pressure extraction plant (NOVA-Swiss, Effretikon, Switzerland) at 40 C and 300 bars during 10 hours. The CO 2 flow rate was 3.59 g/min. The pressure and temperature in the separator were bars and C, respectively. Oleoresin yield was measured periodically (every 15 minutes in the first hour; every 30 minutes in the second hour; every 60 minutes to the end of the process), in order to obtain the extraction curve. Total dry matter in ground paprika was assessed by drying to constant weight (13); the mean diameter of ground paprika particles was measured by sieving the sample through EWREKA sieves (14). The extractable colour of ground paprika was determined according to ASTA 20.1 method (15). The microbiological analysis was performed according to the valid regulations (16). The content of minerals and heavy metals was assayed by AAS, using Varian SpectrAA-10 (17). Extractable colour and microbiological analysis of the obtained oleoresins were performed according to the above methods. 78

3 RESULTS AND DISCUSSION Total dry matter in the ground paprika was 93.42%, which is in accordance with the official regulation (18). The mean diameter of particles was 0.28 mm, which is in the range optimal for extraction process (19), because the fruit structure is destroyed, i.e. the active compounds diffusion time is shortened and the active surface for mass transfer is increased, which intensifies the extraction process. Oleoresin yields by supercritical and conventional extraction were 9.98% and 11.83% respectively, which is the result of different solvating power of organic and supercritical fluids (12, 19-21). In the supercritical CO 2 extraction, oil solvating capacity is influenced by the applied temperature and pressure. Extraction curve was obtained by plotting the yield of oleoresin versus extraction time (Fig. 1). An initial linear increase of oil solubility can be observed in the first phase of extraction curve, reaching a plateau and maximum yield in the second phase (22-24). Figure 1. Supercritical CO 2 extraction curve of ground paprika at 40 C and 300 bars Oil and water content, pericarp/calyx/seed ratio, and processing parameters (drying regime and temperature of drying, grinding conditions, particle dimensions, storage conditions) are some of the factors that influence the colour of ground paprika. Hence, the colour has to be measured using some objective method such as extractable colour (15). The extractable colours of commercial ground paprika and its conventional and supercritical oleoresins obtained in this experiment are shown in Table 1. Table 1. Extractable colour of commercial ground paprika and its conventional and supercritical oleoresins Sample ASTA 20 Ground paprika Extract obtained by Soxhlet extraction Extract obtained by supercritical extraction

4 Commercial ground paprika had the lowest colour value, ASTA units, which is considered as still acceptable (25) for this sample for home and industrial application. Among oleoresins, supercritical extract had lower extractable colour in comparison to Soxhlet, confirming higher selectivity of supercritical carbon dioxide than organic solvent (26-28). SC-CO 2 is a good solvent for lipophilic (non-polar) compounds, while it has a low affinity to polar compounds (19). Mineral matter content measurements in ground paprika (Table 2) showed that the paprika fruit was rich in potassium and magnesium, and relatively poor in sodium. From health aspects, it is advisable to use food with lower sodium to potassium ratio. Potassium prompts the elimination of sodium; faster heart beats, dizziness, hearing hiccups, backwards in body growth, infertility and muscular weakness could be the consequences of potassium deficiency. Paprika can be classified into category of food rich in potassium. Content of heavy metals was is agreement with the valid regulations (29). Table 2. Contents of mineral matter and heavy metals in ground paprika Mineral Content (mg/kg) Na K Ca Mg Fe Mn Zn Cu 7.06 Heavy metal Pb < 0.25 As < 0.25 Cd 0.06 Cr 0.34 Co < 0.25 Ni 1.28 The results of microbiological analyses of ground paprika and oleoresins are shown in Table 3. Table 3. Results of microbiological analyses of ground paprika and oleoresins obtained by supercritical (SC) and Soxhlet (Sox) extraction Microorganism Ground paprika SC oleoresin Sox. oleoresin E. coli Proteus species Salmonella Sulphite-reducing Clostridium + Coagulase positive staphylococci Total colony counts 500,000 Moulds 200,000 Yeasts 80

5 Total colony counts in ground paprika satisfied the stipulations of the regulations (16). However, moulds (present in higher number than allowed) and sulphite-reducing Clostridium [not allowed presence, according to the official regulations (16)] represent a health risk. It is known that moulds and spores of sulphite-reducing Clostridium survive the heat treatment of drying of paprika fruits, it can be assumed that some omissions were made of in the washing or sterilization in the process of ground paprika production. On the other hand, microbiological tests did not prove the presence of any microorganisms, i. e., the samples were sterile. Despite the low daily intake, paprika and its products are considered as very important healthy food or food supplements, thanks to a high content of bioactive compounds. CONCLUSION Commercial ground paprika fruit tissue structure was broken and ground to the level that allowed diffusion of active compounds, intensified mass transfer and extraction. As a consequence, by the extraction with organic solvents a high yield of extract was obtained, which is in accordance with the results obtained by other authors (22, 30). The yield of the extract obtained by conventional extraction (Soxhlet) was 11.83%. The yield of the extract obtained by supercritical CO 2 extraction was 9.98%. Extractable colour (ASTA) in ground pepper was lower than in oleoresins, since oleoresins represent pigment concentrate in oily medium. Extractable colour of Soxhlet and supercritical oleoresins were and ASTA respectively, which indicated a lower selectivity of the organic solvent in comparison to supercritical carbon-dioxide. Paprika extracts showed no microbial contamination, which is a consequence of the extraction conditions applied. This fact once again confirms the advantages of using extracts instead of dried spices (12, 27, 30-32). ACKNOWLEDGEMENTS This research is part of the Project No which is financially supported by the Provincial Secretariat for Science and Technological Development of Vojvodina. REFERENCES 1. Deli, J., Pfander, H., Tóth, G: Investigation of carotenoid composition of paprika paste. Chromatogr. Suppl. 56 (2002) S177-S Deli J., Matus. Z., Molnár, P., Tóth, G.: Separation and identification of carotenoids from different coloured paprika (Capsicum annuum) by reversed-phase high-performance liquid chromatography. Eur. Food Res. Technol. 213 (2001) Deli, J., Molnár, P., Matus, Z., Tóth, G.: Carotenoid composition in the fruits of red paprika (Capsicum annuum var. lycopersicum rubrum) during ripening: biosynthesis of carotenoids in red paprika. J. Agric. Food Chem. 49, 3 (2001)

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