verticale

Kernel carbohydrates concentration in sugary-1, sugary enhanced and shrunken sweet corn kernels

(in lingua inglese )

The results of this study indicate clearly that the date of sweet corn harvest is the most important factor in maintaining fresh sweet corn quality. It was observed that the more mature sweetcorn (III date of harvest) had larger kernels and the kernels were more compact on the cob, while the less mature (I date of harvest) kernels were smaller and there were still some spaces between the kernel rows. The delay of the corncobs harvest date affected the sweet corn quality. The moisture content and sugars concentration decreased but starch level increased. The rise of starch concentration was more quickly between su-1 sweet corn varieties than se or sh2.

Scarica il PDF Scarica il PDF
Aggiungi ai preferiti Aggiungi ai preferiti


Articoli tecnico scientifici o articoli contenenti case history
Articolo Agriculture and Agricultural Science Procedia, 2015

Pubblicato
da Alessia De Giosa




Settori: 

Parole chiave: 


Estratto del testo
Agriculture and Agricultural Science Procedia 7 ( 2015 ) 260 '' 264 2210-7843 © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Peer-review under responsibility of the Centre wallon de Recherches agronomiques (CRA-W)
doi: 10.1016/j.aaspro.2015.12.044 Available online at www.sciencedirect.com ScienceDirect ScienceDir Farm Machinery and Processes Management in Sustainable Agriculture, 7th International Scientific Symposium Kernel carbohydrates concentration in sugary-1, sugary enhanced and shrunken sweet corn kernels Mariusz Szymaneka*, Wojciech Tana'a, Flaieh Hammed Kassarb a University of Life Sciences in Lublin, Department of Agricultural Machinery, G''boka 28, 20-612 Lublin, Poland b University of AL- Muthanna, Rumaitha Samawa, Iraq Abstract Sweet corn remains at its optimum harvest maturity for a very short period, and quality changes rapidly following its peak. This
study investigates the changes in carbohydrate concentration of three genotypes of sweet corn: sugary (su-1), sugar enhanced (se)
and supersweet or shrunken (sh2) at three stages of maturity. The analysis of variance revealed differences between genotypes for
carbohydrates (sugars and starch) and between stages of maturity (moisture content). Average sugar concentration of su-1 corn
was 5% higher than that of se corn and 52% higher than that of sh2 corn. The average starch concentration of su-1 corn was 27%
lower than that of se corn and 66% lower than that of sh2 corn. The average moisture content of su-1 corn was 3% lower than
that of se corn and 1% lower than that of sh2 corn.

© 2015 The Authors. Published by Elsevier B.V.
Peer-review under responsibility of the Centre wallon de Recherches agronomiques (CRA-W). Keywords: genotype;, maturit;, moisture; sugars; starch. 1. Introduction In Europe, as well as in Poland, the areas cultivated with sweet corn (Zea mays L. var saccharata) have increased considerably, during the last ten years. Sweet corn eaten in the immature stage is widely used for human
consumption throughout the world. It is important source of fiber, minerals, and certain vitamins. It is produced for * Corresponding author. Tel.: +048 081 512 246 814; E-mail address: mariusz.szymanek@up.lublin.pl © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Peer-review under responsibility of the Centre wallon de Recherches agronomiques (CRA-W) 261 Mariusz Szymanek et al. / Agriculture and Agricultural Science Procedia 7 ( 2015 ) 260 '' 264 three distinct markets: fresh, canning, and freezing. The sweet corn varieties suitable for processing vary according
to the products, canned or frozen. In recent years, sweet corn harvested for processing has been greatly improved by
selective breeding and hybridizing. Nearly all commercially grown sweet corn is now of hybrid varieties. These
varieties offer greatly increased yields and better uniformity, with excellent flavor, color, and processing quality
(Kumar et. al, 2006). The primary components of fresh sweet corn eating quality associated with consumer
performance are flavor (mainly sweetness), kernel texture and aroma (Azanza et al., 1996). Kernel sugar
concentrations have been correlated with sweetness and taste panel preference (Evensen and Boyer, 1986; Azanza et
al., 1994). Sweetness and tenderness were found to be the most important in overall quality, in a study conducted
with fresh and processed sweet corn. Kernel sucrose concentration is regulated by endosperm carbohydrate
metabolism during kernel development. New varieties of sweet corn have been developed with improved
consistency, taste and shelf life (Kamol and Pulam, 2007). In sweet corns, the enhancement of sweet components in
kernels is made successfully by reduction of starch synthesis activities and increase in sucrose accumulation. There
are many different endosperm mutations in corn that influence kernel carbohydrate metabolism (Coe and Polacco
1994). Traditional sweet corn is homozygous for the sugary 1 (sh1) mutation. Comparison to normal field corn, su1
endosperms accumulate more sugar and a highly branched, water soluble form of starch known as phytoglycogen at
harvest maturity. Sweet corn su1 varieties are characterized by a rapid loss of kernel quality after harvest due to the
conversion of sugars to starch and moisture loss (Azanza et al., 1996). This rapid decline in quality restricts the time
available for shipment from growing regions to major marketing areas and provides a narrow window to the sweet
corn processing industry (Marshall and Tracy, 2003). Shrunken2 (sh2) and sugary enhancer1 (se1) are endosperm
mutations of increasing importance to the sweet corn industry due to their superior eating quality. Preferred by
consumers, owing to greater (two to three times more) kernel sucrose concentration (sh2) at fresh harvest retain
higher sugar and moisture concentration for longer postharvest periods than the traditional variety (sh1). These
varieties retain higher sugar and moisture concentration for longer postharvest periods and have only trace levels of
phytoglycogen in comparison to su1 kernels (Malvar et al, 1997). This longer postharvest life provides the industry
with more time to transport, process, and market a product with superior eating quality (Azanza, 1996). Sweet corn
genotypes with either sh2 or su1 se1 have also been shown to be preferred by consumers in taste panels (Evensen
and Boyer, 1986). Supersweet varieties have become the dominant type produced in virtually all the major sweet
corn producing regions of the Poland. Despite the desirable attributes of sh2 and su1 se1 corn, the utilization of
these two endosperm mutations has been hindered by reduced field emergence, seedling vigor and stand uniformity
and stand uniformity (Douglass, 1993). Goldman and Tracy (Goldman and Tracy, 1994) reported that kernels
containing the sh2 mutant have a much smaller endosperm than su1 due the effects of this mutant on starch
synthesis. Reductions in endosperm size result in smaller, lighter kernels.
Several kernel characteristics in fresh sweet corn have been related to sensory quality. Pericarp thickness has been
negatively associated with the sensory perception of tenderness (Juvik and Labonte, 1988). Sweet corn flavor and
texture are associated with the chemical composition of the kernel, the structural compactness of starch granules,
and the cellular structure of the endosperm (Tracy, 2001). The objective of the study was to measure carbohydrates concentrations of three genotypes of sweet corn: sugary (su-1), sugar enhanced (se) and supersweet or shrunken (sh2) at three stages of maturity (SM). 2. Materials and methods Three genotypes of commercial sweet corn cultivars, a cultivar recessive for the sugary (su-1) (Boston), sugar enhanced (se) (Anawa) and supersweet or shrunken (sh2) (Candle) were compared during maturation period for
carbohydrate composition and yield for processing quality. Sweet corn for these studies was grown during 2013 in
University of Life Sciences Research Station, near Lublin, Poland. The cultivars were grown in isolation, about 200
m, from one another to reduce the likelihood on cross-pollination. Harvests of ears for physical and chemical analyses were made at 4 '' day intervals from 20 to 32 days after pollination (DAP). These stages were chosen because sugars reach maximum levels at about 21 DAP and sweet corn
typically is harvested at this stage of maturity (Carey et al., 1984). At each harvest date, ears were hand picked at
random for each genotype. Directly after harvest, ears were husked and silk was removed. Next the ears were frozen
in liquid nitrogen to stop all metabolic activity. Thirty kernels of corn ears were randomly removed and ground into
powder in laboratory grinder, and stored in freezer at about -20qC for subsequent carbohydrate analyses. 262 Mariusz Szymanek et al. / Agriculture and Agricultural Science Procedia 7 ( 2015 ) 260 '' 264 Measurement of sugar contents was made using the DNS method following acid hydrolysis (PN-EN ISO 10520, 2002). The reducing sugars were determined prior to the hydrolysis by means of the DNS method. The
starch content was determined through the difference between the total content of sugars and the content of sugars
soluble in ethyl alcohol (40% vol/vol). The sucrose content was established through the difference between the
content of sugars soluble in ethyl alcohol and the content of reducing sugars. To determine the reducing sugar
content with the DNS method, a test tube was filled with 0.5 cm3 of the tested solution and 1.5 cm3 of 3-5-
dinitrosalicylic acid (DNS) and then boiled for 5 minutes in a bath of boiling water. After cooling down, 6 cm3 of
distilled water was added to make a total volume of 8 cm3. Next, the sample extinction was read against a reagent
assay at a wavelength of O = 550 nm. The extinction measurement results were referenced to the model curve. The
sugar content was determined in relation to the kernel dry mass. The experiments were replicated thrice in 100-gram
samples for each variety and the average values were reported. The moisture content of the kernels was determined using the ASAE (1983) method. This involved oven drying of seed samples at 103°C for 72 h. The samples were allowed to cool in a desiccator after which the weights were
recorded. Three samples were used and the average moisture content was reported. Data were subjected to analysis of variance (ANOVA). Comparison of means was conducted with Tukey's least significant difference (LSD) test, at a significance level p = 0.05. All statistical analysis was performed using the
Statistica 6.0. 3. Results and discussion Sweet corn kernel concentration of carbohydrates and moisture are presented in Table 1.
Table 1. Mean sweet corn kernel concentration of carbohydrates and moisture of three fresh sweet corns at three stages of maturity. Stage
of
maturity Carbohydrates
Moisture, % Genotypes Varieties Sugar, %
Sugar, % Starch, %
Starch% su-1 Boston I 5.2a 15.7a 74.6a II 5.3b 20.1ba 69.4ba III 4.6cab 24.6cab 64.2cab Bonus I 5.9a 16.1a 72.5a II 5.7b 19.2ba 67.1ba III 4.9cab 23.8cab 60.2cab Jubilee I 5.4a 15.2a 74.6a II 5.1b 19.6ba 66.8ba III 4.6cab 23.7cab 58.7cab Mean - 5.1 19.7 67.5 LSD (0.05) - 0.4 3.2 5.1 se Anava I 6.5a 12.3a 72.3a II 5.2ba 16.3ba 61.2ba III 4.7ca 18.8ca 59.4ca Champ I 6.2a 11.9a 71.9a II 4.8ba 14.2ba 65.5ba III 4.3ca 17.2cab 57.8cab Dallas I 6.8a 12.8a 74.6a II 5.6ba 15.6ba 65.7ba III 5.1ca 19.9cab 59.7cab Mean - 5.4 14.4 65.3 LSD (0.05) - 1.1 2.1 4.3 sh2 Candle I 8.3a 6.3a 71.9a II 7.6ba 6.8b 67.1ba III 7.2cab 7.6c 59.6cab Challenger I 8.9a 6.1a 73.6a II 7.6ba 6.7b 67.3ba III 6.9cab 7.5c 58.6cab Sheba I 8.7a 5.8a 75.2a II 8.2ba 6.6b 67.2ba 263 Mariusz Szymanek et al. / Agriculture and Agricultural Science Procedia 7 ( 2015 ) 260 '' 264 Stage
of Carbohydrates
Moisture, % Genotypes Varieties III 7.6cab 7.3c 61.6cab Mean - 7.8 6.7 66.9 LSD (0.05) - 0.4 1.6 4.6 Genotypes
LSD (0.05) 0.6 5.4 66.9 Within each column, the same letter indicates the significant difference at p < 0.05. The analysis of variance showed significant difference between genotypes type, and stage of maturity for
carbohydrates and moisture concentration. Carbohydrates per kernel did not differ between cultivars.
The delay of the corncobs harvest date affected the changes of moisture, sugars and starch concentrations. A similar
trend was reported by Simonne et al. (1999), Suk and Sang (1999), Waligóra (2002), Warzecha (2003) and Liu-Peng
et al. (2003). The results show that delaying the harvest date decreasing moisture and sugars and leads to an increase
in the starch concentrations. Negative associations between sugar content and starch content were also observed by
Dudley and Lambert (1992), Ha (1999), Kumari et al. (2006). The highest decrease of moisture contents (21.3%) was obtained for the Jubilee variety and the lowest (13.9%) for the Boston variety. The average moisture content of the su-1 sweet corn varieties (17.3%) was 19.6% lower than
the moisture content of the se varieties (13.9%) and 21.3% lower than sh2 varieties (21.3%). The average sugars concentrations of the three cultivars of su-1 genotype types (5.6%) for I stage of maturity was 16% lower than the sugars concentration of III stage of maturity (4.4%). Respectively for cultivars of se and sh2
genotype types this was obtained: 27.6% and 15.8%. Results from the investigation demonstrate that sugars
concentration in sh2 kernels is significantly higher by about 32% in I date of harvest, by about 50% in II date of
harvest and by about 53% in III date of harvest than sugars concentration in se kernels and by about 48% in I date of
harvest, by about 47% in II date of harvest and by about 53% in III date of harvest than sugars concentration in su-1
kernels. Table 1 indicates starch concentration was 56.0% higher in su-1 in III stage of maturity than in I stage of
maturity. The starch concentrations of se and sh2 genotype types were 51.5% and 19.6% higher, respectively. Starch concentration in sh2 kernels is significantly lower by about 105% in I date of harvest, by about 143% in II date of harvest and by about 151% in III date of harvest than sugars concentration in se kernels and by about
160% in I date of harvest, by about 192% in II date of harvest and by about 224% in III date of harvest than sugars
concentration in su-1 kernels. 4. Conclusion The results of this study indicate clearly that the date of sweet corn harvest is the most important factor in maintaining fresh sweet corn quality. It was observed that the more mature sweetcorn (III date of harvest) had larger
kernels and the kernels were more compact on the cob, while the less mature (I date of harvest) kernels were smaller
and there were still some spaces between the kernel rows. The delay of the corncobs harvest date affected
the sweet corn quality. The moisture content and sugars concentration decreased but starch level increased. The rise
of starch concentration was more quickly between su-1 sweet corn varieties than se or sh2. References ASAE Standards, 1983. S352.1. Moisture measurement '' grains and seeds. St. Joseph Mich.: ASAE.
Azanza, F., Klein, B.P., Juvik, J.A., 1996. Sensory characterization of sweet corn lines differing in physical and chemical composition. Journal of
Food Science 61, 253-257.
Azanza, F., Juvik, J.A., Klein, B.P., 1994. Relationship between sensory quality attributes and kernel chemical compositions of fresh and frozen
sweet corn. Journal of Food Science 61(1), 253-257.
Carey, E.E., Rhodes, A.M., Dickinson, D.B., 1982. Postharvest levels of sugars and sorbitol in sugary enhancer (su se) and sugary maize (su Se).
HortScience 17, 241''242.
Coe, E.H., Polaco., 1994. Gene list and working maps. Maize Genet. Coop. Newslett., 68, 157-208.
Douglass, S.K., Splittstoesser, W.E., 1993. Sweet corn seedling emergence and variation in kernel carbohydrate reserves. Seed science and
technology 21(2), 433-445.
Dudley J.W., Lambert, R.J., 1992. Ninety generations of selection for oil and protein in maize. Maydica 37, 1-7. 264 Mariusz Szymanek et al. / Agriculture and Agricultural Science Procedia 7 ( 2015 ) 260 '' 264 Evensen, K.B., Boyer, C.D., 1986. Carbohydrate composition and sensory quality of fresh and stored sweet corn. Journal of the American
Society for Horticultural Science 111(5), 734-738.
Goldman, I.L., Tracy, W.F., 1994. Kernel protein concentration in sugary-1 and shrunken-2 sweet corn. HortScience 29(3), 209-210.
Ha, V., 1999. Genetic analysis of some yield components and kernel quality in sweet corn. Romania Agrıculture Research 11-12, 9-20.
Juvik, J.A., Labonte, D.R., 1988. Single-kernel analysis for the presence of the enhancer (se) gene in sweet corn. HortScience 23, 384-386.
Kamol, L., Pulam, T., 2007. Breeding for increased sweetness in sweet corn. International Journal of Plant Breeding 1(1), 27-30.
Kumari, J., Gadag, R.N., Jha, G.K., 2006. Heritability and correlation studies in sweet corn for quality traits, field emergence and grain yield.
MNL 80,18-19.
Marshall, S.W., Tracy, W.F., 2003. Sweet corn. In: Ramstad P.E., White P. (eds): Corn Chemistry and Technology. American
Malvar, R.A., Revilla, P., Cartea, W.F., Ordas. 1997. A Field corn inbreds to improve sweet corn hybrids for early vigor and adaptation to
European conditions. Maydica 42(3), 247-255.
Liu-Peng, Hu-Chang Hao, Dong-Shu Ting, Wang-Kong Jun., 2003. The comparison of sugar components in the developing grains of sweet corn
and normal corn. Agricultural Science in China 2, 258-264.
PN-EN ISO. 2002. ISO 10520: Native starch - Determination of starch content - Ewers polarimetric method. Poland: ISO (in Polish).
Simonne, E., Simonne, A., Boozer, R., 1999. Yield, ear characteristics, and consumer acceptance of selected white sweet corn varieties in the
southeastern United States. Hort Technology 1, 289-293.
Suk, S.L., Sang, H.Y., 1999. Sugars, soluble solids and flavor of sweet, super sweet and waxy corns during grain filling. Korean Journal of Crop
Science 44, 267-272.
Tracy, W.F., 2001. Sweet corn, p. 155''197. In: A.R. Hallauer (ed.). Specialty corns. 2nd ed. CRC Press, Boca Raton, Fla.
Waligóra, H., 2002. Kukurydza cukrowa i możliwo'ci jej uprawy w Polsce. Wie' Jutra 47, 20-23.
Warzecha, R., 2003. S'odki smak kukurydzy. Owoce Warzywa Kwiaty 6, 20-21.


© Eiom - All rights Reserved     P.IVA 00850640186