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RHEOLOGICAL AND TEXTURAL CHARACTERISTICS OF RAW AND PAR‐COOKED TAEWA (MAORI POTATOES) OF NEW ZEALAND
Author(s) -
SINGH J.,
KAUR L.,
McCARTHY O.J.,
MOUGHAN P.J.,
SINGH H.
Publication year - 2008
Publication title -
journal of texture studies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.593
H-Index - 54
eISSN - 1745-4603
pISSN - 0022-4901
DOI - 10.1111/j.1745-4603.2008.00139.x
Subject(s) - cultivar , dry matter , specific gravity , rheology , food science , starch , horticulture , chemistry , botany , materials science , mineralogy , biology , composite material
The quality characteristics of raw and par‐cooked (partially cooked) tubers from four different Taewa cultivars were evaluated and compared with a modern potato cultivar (Nadine). Significant differences in dry matter, starch content, color and specific gravity were observed among the raw tubers from the different cultivars. Moemoe and Tutaekuri Taewa cultivars showed higher dry matter content (21.97 and 21.57%, respectively) whereas the lowest specific gravity of 1.057 was observed for Nadine. Par‐cooked chef‐ready tubers were prepared from each cultivar and evaluated for quality during 21 days of storage at 4C. Tutaekuri raw as well as par‐cooked tubers had higher fracturability and hardness whereas Nadine par‐cooked tubers had higher adhesiveness than other cultivars. Rheological parameters such as storage modulus ( G′ ), loss modulus and loss tangent (tan δ ) were dependent on the dry matter and starch contents of the tubers. The highest peak G′ values of 24,930 Pa and 19,700 Pa were observed for Tutaekuri and Moemoe potato cultivars, respectively.PRACTICAL APPLICATIONS Ready‐to‐microwave par‐cooked tubers with a refrigerated shelf life of 21 days were developed without using any chemical preservatives. The rheology of the tuber tissue was studied using a dynamic rheometer for the first time. The technique allows the continuous monitoring of the changes occurring in the potato tissue during the heating and cooling cycles. Significant correlations between the textural characteristics of raw and cooked tubers and the dynamic rheological characteristics of fresh tubers were observed. The technique may be helpful in predicting the viscoelastic characteristics of raw potatoes and the changes in the texture of cooked tubers during refrigerated storage.