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Chemical and Microbiological Changes in Blueberries and in Hypertonic Solution during Osmotic Dehydration Employing Reused Concentrate
Author(s) -
Kucner Anna,
Papiewska Agnieszka,
Sójka Michał,
Klewicki Robert
Publication year - 2013
Publication title -
journal of food process engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 45
eISSN - 1745-4530
pISSN - 0145-8876
DOI - 10.1111/jfpe.12024
Subject(s) - dehydration , chemistry , osmotic dehydration , food science , mesophile , tonicity , polyphenol , dry matter , chromatography , biochemistry , botany , bacteria , biology , genetics , antioxidant
Dehydration was carried out in 65° B rix sucrose solution at 40 C for 120 min. The solution was used 15 times, each time a new batch of fruits was processed. Prior to dehydration, the fruits were subjected to pretreatment by immersion in solutions containing pectinolytic and lipolytic enzymes. Following dehydration, the dehydrated material and osmotic solution were tested for the content of dry matter (36.6 ± 3.3% [w/w] and 58–61° B rix, respectively), total polyphenols (1,738 ± 289 mg/100 g initial dry matter [ IDM ]), anthocyanins (606 ± 58 mg/100 g IDM ) and flavan‐3‐ols (695 ± 139 mg/100 g IDM ). The highest retention of anthocyanins was observed for cyanidin‐3‐ O ‐glucoside (over 81%), petunidin‐3‐ O ‐glucoside, malvidin‐3‐ O ‐arabinoside and malvidin‐3‐ O ‐glucoside (over 74%). The average retention of procyanidins in fruits was 77%. The pH value of the hypertonic solution remained at the level of 3.4–3.7. The syrup used for osmotic dehydration was characterized by a relatively low quantity of mesophilic bacteria (<10 3 cfu/mL) but a higher contamination with osmotolerant yeasts and molds (from 1 × 10 3 to 2.5 × 10 4 cfu/mL). Practical Applications The article deals with osmotic dehydration, which is a method that allows a partial removal of water from plant material. Using this method, one can obtain high‐quality products because the water removal is conducted without phase change. However, considerable amounts of hypertonic solution (used for osmotic dehydration) pose a problem. Management of spent syrup is one of the most important problems related to osmotic dewatering. Thus, repeated use of hypertonic solution is indispensable; however, it may have an influence on the product quality. The paper presents the chemical and microbiological changes that occur during osmotic dehydration of highbush blueberry fruits over 15 cycles employing reused sucrose solution. Prior to dehydration, the fruits were subjected to pretreatment by immersion in solutions containing pectinolytic and (which is a new approach to pretreatment before osmotic dehydration) lipolytic enzymes. The results indicate that applied procedure enables to obtain osmodehydrated berries without a large decrease in the product quality.