During freezing of starch gels, starch-rich regions are formed in
the matrix, where water remains partly unfrozen. High solid concentration
in the regions assists connection of the starch chains
resulting in thick filaments, whereas water molecules convert into
ice crystals and a separate phase is formed. Upon thawing, ice
converts to a bulk phase water and releases easily from the polymeric
network. This process is known as syneresis (Yuan &
Thompson, 1998). The freezeethaw stability (syneresis) of the
samples is presented in Fig. 3. In the absence of acetic acid, the
syneresis of both samples increased with increasing numbers of
freezeethawing cycles. The syneresis of the PG starch increased
steadily (Fig. 3A) while a rapid increase in the syneresis of the
GCWS sample was observed after the first freezeethawing cycle
followed by a stabilization (Fig. 3B). The syneresis of PG starch was
initially 20.87% and slightly increased to 21.80% after five freezeethaw
cycles (overall 4.28% increase). For the GCWS starch, the
syneresis was 17.23% in the beginning which increased rapidly to
20.78% after the second freezeethawing cycle (17.08% increase).
Then, the syneresis increased only slightly from 20.78% to 21.03%
(1.18% increase) after the 2nd cycle. Overall, from the first to the
fifth freezeethawing cycles, the syneresis of GCWS increased
18.08%. Comparing the values obtained for the two samples, it is
clear that the PG had greater syneresis than GCWS starch. Nevertheless,
during the five freezeethawing cycles less changes in the
syneresis of PG was observed than the GCWS (4.28% vs 18.08%). The
higher syneresis values of PG starch compared to GCWS starch may
be related to its lower water absorption capacity, the absence of
starch granules and freedom of the starch molecules to interact
with each other during freezing of the starch gel. These factors are
likely to result in greater water loss during thawing. However, the
granules of the GCWS starch can retard rapid re-association of
starch molecules during freezing and uptake more water during
thawing resulting in less syneresis compared to PG starch (Chen &
Jane, 1994b).
During freezing of starch gels, starch-rich regions are formed inthe matrix, where water remains partly unfrozen. High solid concentrationin the regions assists connection of the starch chainsresulting in thick filaments, whereas water molecules convert intoice crystals and a separate phase is formed. Upon thawing, iceconverts to a bulk phase water and releases easily from the polymericnetwork. This process is known as syneresis (Yuan &Thompson, 1998). The freezeethaw stability (syneresis) of thesamples is presented in Fig. 3. In the absence of acetic acid, thesyneresis of both samples increased with increasing numbers offreezeethawing cycles. The syneresis of the PG starch increasedsteadily (Fig. 3A) while a rapid increase in the syneresis of theGCWS sample was observed after the first freezeethawing cyclefollowed by a stabilization (Fig. 3B). The syneresis of PG starch wasinitially 20.87% and slightly increased to 21.80% after five freezeethawcycles (overall 4.28% increase). For the GCWS starch, thesyneresis was 17.23% in the beginning which increased rapidly to20.78% after the second freezeethawing cycle (17.08% increase).Then, the syneresis increased only slightly from 20.78% to 21.03%(1.18% increase) after the 2nd cycle. Overall, from the first to thefifth freezeethawing cycles, the syneresis of GCWS increased18.08%. Comparing the values obtained for the two samples, it isชัดเจนว่า PG จะมี syneresis สูงกว่าแป้ง GCWS อย่างไรก็ตามในระหว่างรอบ freezeethawing 5 น้อยกว่าการเปลี่ยนแปลงในการsyneresis PG ถูกสังเกตกว่า GCWS (4.28% vs 18.08%) ที่ค่าที่สูงกว่า syneresis ของ PG แป้งเปรียบเทียบกับแป้ง GCWS อาจเกี่ยวข้องกับของต่ำน้ำดูดซึมกำลังการผลิต การขาดงานของเม็ดแป้งและอิสรภาพของโมเลกุลแป้งเพื่อโต้ตอบกันในระหว่างการแช่แข็งของแป้งครีม ปัจจัยเหล่านี้คือแนวโน้มที่จะทำให้สูญเสียน้ำมากขึ้นระหว่าง thawing อย่างไรก็ตาม การเม็ดแป้ง GCWS สามารถถ่วงสมาคมอีกครั้งอย่างรวดเร็วแป้งโมเลกุลระหว่างจุดเยือกแข็งและดูดซับน้ำเพิ่มเติมระหว่างthawing เกิด syneresis น้อยเมื่อเทียบกับแป้ง PG (Chen &เจน 1994b)
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