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Continuous Flow Microwave‐Assisted Processing and Aseptic Packaging of Purple‐Fleshed Sweetpotato Purees
Author(s) -
Steed L.E.,
Truong V.D.,
Simunovic J.,
Sandeep K.P.,
Kumar P.,
Cartwright G.D.,
Swartzel K.R.
Publication year - 2008
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1750-3841.2008.00950.x
Subject(s) - microwave , chemistry , aseptic processing , food science , water activity , sterilization (economics) , shelf life , absorbance , oxygen radical absorbance capacity , dpph , materials science , chromatography , antioxidant , water content , biochemistry , physics , geotechnical engineering , quantum mechanics , monetary economics , engineering , economics , foreign exchange market , foreign exchange
Pumpable purees from purple‐flesh sweetpotatoes (PFSP) were subjected to microwave heating using a 60 kW, 915 MHz continuous flow system, followed by aseptic packaging in flexible containers to obtain a shelf‐stable product. Initial test runs were conducted using a 5 kW 915 MHz microwave system to measure dielectric in‐line properties and examine the puree temperature profiles. The results demonstrated uniformity in heating of the puree at sterilization temperatures (>121 °C), and the dielectric constants and loss factors were within the range of published values for orange‐fleshed sweetpotato purees. The pilot‐scale test runs in a 60 kW microwave unit produced shelf‐stable puree packages stable at room temperature. Polyphenolic content of the PFSP purees were evaluated and the results showed that while total phenolics increased (5.9%) and total monomeric anthocyanins slightly decreased (14.5%) with microwave application, antioxidant activity determined by 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging activity and oxygen radical absorbance capacity (ORAC) assays did not significantly change as a result of microwave processing. Color values showed that microwave‐processed samples differed from fresh puree in saturation and hue angle, but not in overall color change. PFSP purees increased in gel strength when microwave processed, packaged, and stored, but the gel could be easily disrupted into flowable purees. Overall, high‐quality retention can be obtained by microwave processing and aseptic packaging of PFSP purees so that they can be used as functional food ingredients.