increased after boiling and roasting, while malic acid decreased.
The content of ascorbic acid decreased by 33% and 37% after boiling
and roasting, respectively (Barros et al., 2011).
To establish the relationship between the different variables in
fresh and cooked chestnuts, PCA was applied to total starch, amylose,
crude fat, crude protein, water-soluble protein, reducing
sugar, sucrose, glucose, fructose, total polyphenols, total flavonoids
and organic acids (Fig. 1). An eigenvalue of 100% was achieved
using two PCs (PC1 = 99%, PC2 = 1%). Fresh chestnuts were clearly
distinguished from boiled, roasted and fried chestnuts, while
roasted chestnuts were similar to fried chestnuts because of similar
cooking conditions.
3.3. Volatile components in fresh and cooked chestnuts
The main volatiles in fresh chestnuts were esters and aldehydes,
which mainly included ethyl acetate (92.46%), nonanal (1.81%),
hexanal (1.54%), butyl acetate (1.20%), and benzaldehyde (0.55%),
13 compounds in total (Table 4). The primary volatiles in fried
chestnuts were furfural (36.58%), hexanal (14.18%), nonanal
(10.73%), 3-heptanone (8.87%), and 4-hydroxy-2-butanone
(6.76%). Ethyl acetate (96.40%), butyl acetate (0.85%), hexanal
(0.77%), nonanal (0.50%) and spiro[2,4]hepta-4,6-diene (0.43%)
were found in boiled chestnuts; ethyl acetate (94.82%), hexanal
(1.26%), butyl acetate (0.97%) and 2-hydroxy-2-cyclopenten-
1-one (0.85%) were found in roasted chestnuts. There was still a
large amount of esters and aldehydes in the thermal processed
chestnuts; moreover, ketones, furfural and furan were found. The
aromatic components of cooked chestnuts mainly come from the
degradation of saccharides, protein and lipids, caramelization of
saccharides, and Maillard reaction between reducing sugar and
amino acids (Morini & Maga, 1995b). Furfural, 3-heptanone,
2-hydroxy-2-cyclopenten-1-one, 4-hydroxy-2-butanone, 3-carene,
1-(methylencyclopropyl)-ethanol, 2-hexenoic acid methyl ester
and 2-pentyl-furan were observed in fried chestnuts but not in
fresh chestnuts, which means that they were formed during thermal
processing. Comparing the obtained results with previous
studies, hexanal, 4-hydroxy-2-butanone, and decanal were also
identified in thermal processed Chinese chestnuts (Morini &
Maga, 1995b); furfural (6.3%) and benzaldehyde (7.2%) were also
found to be main components in roasted Italian chestnuts (Krist
et al., 2004).
4. Conclusions
After thermal processing, the proximate composition, including
starch, fat, water-soluble protein, reducing sugar, L-aspartic acid, Lglutamic
acid, L-arginine, sucrose and other nutritional compounds,
decreased significantly, which led to a decrease in nutritional
value. However, the decrease in reducing sugar and free
amino acids made a great contribution to the flavor formation.
The main volatile components in cooked chestnuts were ketones,
furfural and furan, in addition to the esters and aldehydes that
originated in fresh chestnuts.
Acknowledgements
The authors are thankful for the support of the Forestry Industry
Research Special Funds for Public Welfare Projects (No.
201204401) from the Ministry of Forestry of the People’s Republic
of China and the Fundamental Research Funds for the Central
Universities (2015ZCQ-SW-04).
เพิ่มขึ้นหลังจากที่เดือด และ คั่ว ในขณะที่ลดกรด malicเนื้อหาของกรดแอสคอร์บิคลดลง 33% และ 37% หลังจากที่ต้มและ คั่ว ตามลำดับ (Barros et al. 2011)การสร้างความสัมพันธ์ระหว่างตัวแปรต่าง ๆ ในสด และปรุงสุกเกาลัด PCA กับรวมแป้ง อมิลดไขมัน น้ำมันดิบโปรตีน โปรตีนละลายน้ำได้น้ำตาล ซูโครส กลูโคส ฟรักโทส โพลีฟีนรวม รวมฟลาและกรดอินทรีย์ (1 รูป) สำเร็จ eigenvalue ของ 100%ใช้พีซีสองเครื่อง (PC1 = 99%, PC2 = 1%) เกาลัดสดได้อย่างชัดเจนในขณะที่ต่างจากเกาลัดคั่ว ต้ม และทอดเกาลัดคั่วได้คล้ายกับเกาลัดผัด เพราะคล้ายกันเงื่อนไขในการทำอาหาร3.3 การเปลี่ยนแปลงคอมโพเนนต์ในเกาลัดสด และปรุงสุกVolatiles หลักในเกาลัดสดถูก esters และเอสเทอลดีไฮด์ซึ่งส่วนใหญ่รวมเอทิลอะซิเต (92.46%), nonanal (1.81%),hexanal (1.54%), บิวทิวอะซิเตท (1.20%), และ benzaldehyde (0.55%),สารที่ 13 รวม (ตาราง 4) ทอด volatiles หลักในเกาลัดมี furfural (36.58%), hexanal (14.18%), nonanal(10.73%), 3-heptanone (8.87%), และ 4-ไฮดร็อกซี่-2-บิวทาโนน(6.76%) เอทิลอะซิเต (96.40%), บิวทิวอะซิเตท (0.85%), hexanal(0.77%), nonanal (0.50%) และ spiro [2, 4] hepta-4,6-diene (0.43%)พบในเกาลัดต้ม เอทิลอะซิเตท (94.82%), hexanal(1.26%), บิวทิวอะซิเตท (0.97%) และ 2-ไฮดร็อกซี่-2-cyclopenten -1-1 (0.85%) ที่พบในเกาลัดคั่ว มันยังมีการlarge amount of esters and aldehydes in the thermal processedchestnuts; moreover, ketones, furfural and furan were found. Thearomatic components of cooked chestnuts mainly come from thedegradation of saccharides, protein and lipids, caramelization ofsaccharides, and Maillard reaction between reducing sugar andamino acids (Morini & Maga, 1995b). Furfural, 3-heptanone,2-hydroxy-2-cyclopenten-1-one, 4-hydroxy-2-butanone, 3-carene,1-(methylencyclopropyl)-ethanol, 2-hexenoic acid methyl esterand 2-pentyl-furan were observed in fried chestnuts but not infresh chestnuts, which means that they were formed during thermalprocessing. Comparing the obtained results with previousstudies, hexanal, 4-hydroxy-2-butanone, and decanal were alsoidentified in thermal processed Chinese chestnuts (Morini &Maga, 1995b); furfural (6.3%) and benzaldehyde (7.2%) were alsofound to be main components in roasted Italian chestnuts (Kristet al., 2004).4. ConclusionsAfter thermal processing, the proximate composition, includingstarch, fat, water-soluble protein, reducing sugar, L-aspartic acid, Lglutamicacid, L-arginine, sucrose and other nutritional compounds,decreased significantly, which led to a decrease in nutritionalvalue. However, the decrease in reducing sugar and freeamino acids made a great contribution to the flavor formation.The main volatile components in cooked chestnuts were ketones,furfural and furan, in addition to the esters and aldehydes thatoriginated in fresh chestnuts.
Acknowledgements
The authors are thankful for the support of the Forestry Industry
Research Special Funds for Public Welfare Projects (No.
201204401) from the Ministry of Forestry of the People’s Republic
of China and the Fundamental Research Funds for the Central
Universities (2015ZCQ-SW-04).
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