Utnyttelse av roselleekstrakt i fruktjuice

There has been an increased consumption of fruit juice as consumers have become aware of the nutritional and health benefits of fruit juices. This increased consumption goes together with the growth of varieties of fruit juices and beverages offered for sale. Among these products is roselle (Hibiscus sabdariffa L.) juice, or drink, which is a good source of anthocyanins, vitamins (thiamine, riboflavin, niacin, ascorbic acid) and minerals (Ca, P, Fe). In addition, roselle is also used as flavouring for sauces, jellies, marmalades, soft drinks and as colorant for foods. Roselle extract has low sugar content, and is acidic, so addition of sweetening products like sugar or blending with tropical fruit juices can help to reduce the sourness and improve the sweetness of the juice. The use of roselle extract mixed with tropical fruit juices is also a way of reducing post-harvest losses of fruits which occurs due to lack of good knowledge in processing, preservation, packaging and proper transport systems in most developing countries like Tanzania. Blending of roselle extract with different proportion of tropical fruit juices (mango, papaya and guava) produces roselle-fruit juice blends with improved levels of anthocyanins, vitamin C, total phenolics/phenols, minerals (Ca, Mg, P, Fe and Zn). The amount of vitamin C and Fe were enough to provide recommended daily requirements for adults according to WHO/FAO recommendation while amount of anthocyanins provide enough to meet recommendation of 82 mg and 12.5 mg per day per person in Finland and United States. The roselle-fruit juices found to be high in glucose and fructose. However, as the concentration of roselle extract in the blends increased, the amount of sugars also decreased. Organic acids (malic acid, succinic acid, tartaric acid) increased also with increased concentration of roselle extract in the blends, while the amount of citric acidic increased with increased concentration of tropical fruit juices. The sensory evaluation of the roselle fruit juice blends resulted in the highest acceptance of the roselle-fruit juices with 20% roselle followed by blends with 40% roselle. This was probably due to the reduced acidic taste by adding these low concentrations of roselle to the tropical fruit juices. Colour play a very important role in the acceptability of foods as it is one of the principal characteristics perceived by the senses. The strong colour is due to the presence of anthocyanins in the roselle extract, which imparted the red colour in the blends. The colour of the roselle-fruit juice blends with 80% roselle scored highest among all the sensory parameter evaluated. Storage temperature of the roselle-fruit juice blends showed to have high effect on the anthocyanin content, total phenolic content, vitamin C with significantly losses at higher temperatures. Lower temperature is therefore recommended for long-term storage. Packaging material did not have significant influence on the physicochemical properties of the roselle-mango juice blends. Losses in total monomeric anthocyanins, total phenols and vitamin C were higher in blends stored in plastic bottles compared to glass bottles in higher temperatures. Storage in glass bottles at lower temperatures is therefore recommended for storage of roselle-fruit juice blends.Inntaket av fruktjuicer har økt etterhvert som kunnskapen om helsefordelene ved inntak av slike produkter har blitt bedre kjent, noe som har ført til en økning i juiceutvalget. Blant disse drikkeproduktene finner en også varianter som inneholder roselle (Hibiscus sabdariffa L.). Roselle er en god anthocyaninkilde, og inneholder i tillegg vitaminer (tiamin, riboflavin, niacin og askorbinsyre) og mineraler (Ca, P og Fe). Roselle kan brukes som smakstilsetning i sauser, syltetøy, marmelade og drikkeprodukter og kan også forbedre farge på produktet. Roselle inneholder lite sukker og har høyt syreinnhold. Ved tilsetning av søtningsstoff eller i blanding med tropiske frukter kan en bedre smaksopplevelsen. Bruk av tropiske frukter i blanding med roselle kan også bidra til bedre utnyttelse av disse, men det trengs kunnskap om prosessering, konservering, forpakning og transportmuligheter i de fleste utviklingsland, inkludert Tanzania. Ved å blande roselle i ulike blandingsforhold med tropiske frukter som mango, papaya og guava vil dette gi drikkeprodukter med høyere innhold av anthocyaniner, vitamin C, fenolforbindelser og mineraler (Ca, Mg, P, Fe og Zn). Innholdet av vitamin C og Fe i juiceblandingene tilfredsstiller behovet for disse komponentene for voksne, i henhold til WHO/FAOs anbefalte daglige inntak, mens innholdet av anthocyaniner tilfredsstiller behovet på 82 mg og 12,5 mg pr person anbefalt i Finland og USA. Innholdet av glukose og fruktose i roselle-juiceblandingene var relativt høyt. Ved å tilsette mer roselle i blandingene ble sukkerinnholdet derimot lavere. Innholdet av organiske syrer som eple-, rav- og vinsyre økte med økende konsentrasjon av roselle, mens sitronsyre økte med høyere konsentrasjon av fruktjuice. Sensorisk vurdering viste at roselle-juiceblandingen med 20 % roselle var best likt, deretter 40 % roselle. Dette kan henge sammen med at en ved laveste tilsetting av roselle får lavere syreinnhold og høyere sukkerinnhold i blandingene. Roselle bidrar med en attraktiv rød farge på grunn av innholdet av anthocyaniner, noe som virker tiltalende på konsumenten. Dette var en viktig parameter ved de sensoriske vurderingene, hvor blandinger med 80 % roselle fikk høyest poengsum for utseende. Lagringstemperaturen for juiceblandingene med roselle hadde innvirkning på anthocyaniner, fenoler og vitamin C. Høyere lagringstemperatur viste nedgang i konsentrasjonen av disse komponentene. Av den grunn bør det ferdige produktet lagres ved relativt lav temperatur hvis det skal oppbevares lenge. Valg av pakkemateriale hadde også innvirkning på innholdet av antioksidantegenskapene. Dette ble bekreftet i forsøket med roselle-mangoblandinger. En fant større tap av anthocyaniner, fenoler og vitamin C ved lagring i plastflasker sammenliknet med glassflasker. Lagring av produktet ved 4 ºC og i glassflasker vil være å foretrekke

Utilization of dried roselle calyces extract in fruit juice processing

There has been an increased consumption of fruit juice as consumers have become aware of the nutritional and health benefits of fruit juices. This increased consumption goes together with the growth of varieties of fruit juices and beverages offered for sale. Among these products is roselle (Hibiscus sabdariffa L.) juice, or drink, which is a good source of anthocyanins, vitamins (thiamine, riboflavin, niacin, ascorbic acid) and minerals (Ca, P, Fe). In addition, roselle is also used as flavouring for sauces, jellies, marmalades, soft drinks and as colorant for foods. Roselle extract has low sugar content, and is acidic, so addition of sweetening products like sugar or blending with tropical fruit juices can help to reduce the sourness and improve the sweetness of the juice. The use of roselle extract mixed with tropical fruit juices is also a way of reducing post-harvest losses of fruits which occurs due to lack of good knowledge in processing, preservation, packaging and proper transport systems in most developing countries like Tanzania. Blending of roselle extract with different proportion of tropical fruit juices (mango, papaya and guava) produces roselle-fruit juice blends with improved levels of anthocyanins, vitamin C, total phenolics/phenols, minerals (Ca, Mg, P, Fe and Zn). The amount of vitamin C and Fe were enough to provide recommended daily requirements for adults according to WHO/FAO recommendation while amount of anthocyanins provide enough to meet recommendation of 82 mg and 12.5 mg per day per person in Finland and United States. The roselle-fruit juices found to be high in glucose and fructose. However, as the concentration of roselle extract in the blends increased, the amount of sugars also decreased. Organic acids (malic acid, succinic acid, tartaric acid) increased also with increased concentration of roselle extract in the blends, while the amount of citric acidic increased with increased concentration of tropical fruit juices. The sensory evaluation of the roselle fruit juice blends resulted in the highest acceptance of the roselle-fruit juices with 20% roselle followed by blends with 40% roselle. This was probably due to the reduced acidic taste by adding these low concentrations of roselle to the tropical fruit juices. Colour play a very important role in the acceptability of foods as it is one of the principal characteristics perceived by the senses. The strong colour is due to the presence of anthocyanins in the roselle extract, which imparted the red colour in the blends. The colour of the roselle-fruit juice blends with 80% roselle scored highest among all the sensory parameter evaluated. Storage temperature of the roselle-fruit juice blends showed to have high effect on the anthocyanin content, total phenolic content, vitamin C with significantly losses at higher temperatures. Lower temperature is therefore recommended for long-term storage. Packaging material did not have significant influence on the physicochemical properties of the roselle-mango juice blends. Losses in total monomeric anthocyanins, total phenols and vitamin C were higher in blends stored in plastic bottles compared to glass bottles in higher temperatures. Storage in glass bottles at lower temperatures is therefore recommended for storage of roselle-fruit juice blends

PHYSIO-CHEMICAL, MINERAL COMPOSITION AND ANTIOXIDANT PROPERTIES OF ROSELLE (HIBISCUS SABDARIFFA L.) EXTRACT BLENDED WITH TROPICAL FRUIT JUICES

ABSTRACT Different varieties of fruit juices and beverages are available globally and there has been an increased consumption of fruit juices and beverages due to consumer awareness of nutritional and health benefits. Juice extracts are produced from various parts of plants including leaves, fruits and flowers. Hibiscus sabdiriffa (Roselle) is one such plant whose flowers are used to prepare juices. The roselle extract has a unique red colour, good flavour, low sugar and high acidic content. The acidity makes the juice sour hence the need for addition of sweetening products. A study was conducted on the formulation of roselle extract-tropical fruit blends aimed at establishing its physiochemical, mineral and antioxidant composition. Dried roselle calyces at a ratio of 1:10 (dried roselle calyces: water) were extracted at 50 o C for 30 minutes. The roselle extracts were blended at various proportions of fruit (mango, papaya and guava) juices. Physiochemical, mineral composition and antioxidant properties were evaluated in all the roselle fruit juice blends The results for all rosellefruit blends (80% roselle to 20% roselle) showed that pH ranged between (2.35-3.32), total soluble solids (5.6-10.6 o Brix), titratable acidity (1.28-1.92 %), reducing sugars (2.95-5.55) mg/100g,. Calcium (555.3-23.4 mg/100g DM), Magnesium (213.8-11.5 mg/100g DM), Phosphorus (39.8-9.0 mg/100g DM), Sodium (2.3-5.47 mg/100g DM), Zinc (5.85-0.69 mg/100g DM), Iron (29.5-1.36 mg/100g DM), monomeric anthocyanin (493.5-118.2 mg cyanidin-3-glucoside/100g), vitamin C (40.0-86.5 mg/100g), total phenol (54.6-10.8 mg gallic acid/ 100 g) and antioxidant activity (1.80-1.37 mmol/L). Blending of tropical fruit juices with roselle extract have improved mineral composition and antioxidant properties of fruit juices as roselle is a good source of calcium, magnesium and iron. Antioxidants acts as free radical scavengers inhibit lipid peroxidation and other free radical mediated process, therefore, consumption of roselle-fruit juices with high anthocyanin will protect human body from several diseases attributed to the reactions of free radicals