全 文 ：238 2014, Vol.35, No.16 食品科学 ※包装贮运
Establishment of a Mathematical Model for Treatment of Gynura bicolor
DC. by Nano-Packaging in Combination with Controlled Atmosphere
JIANG Li1, FENG Li1, HOU Tian-ying2, YU Zhi-fang1
(1. College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China;
2. Beijng Vegetable Research Center, Beijng Academy of Agriculture and Forestry Sciences, Beijing 100097, China)
Abstract: The effects of nano-packaging (NP) in combination with controlled atmosphere (CA) on the preservation and
nutritional quality of fresh Gynura bicolor DC (G. bicolor). were investigated during storage at 0 ℃. The nutrition and
quality indices including decay index, respiration rate, as well as the contents of anthocyanin, chlorophyll, amino acid,
protein, total carbohydrate and reducing sugar were tested every 5 days. The combined treatment (CA+NP) improved the
nutritional quality of G. bicolor compared with polyethylene packaging in CA or NP in a modified atmosphere alone. After
20-day storage, CA + NP treatment significantly inhibited respiration intensity and maintained higher contents of total
soluble solids, anthocyanin, chlorophyll, amino acids, protein, total sugar, and reducing sugar. The simplified regression
model: Decay index/%=24.605 - 0.020X7 + 1.122X4 - 0.162X5 (where, X4: reducing sugar content, X5: anthocyanin content,
X7: chlorophyll content) revealed satisfactory goodness of fit (R2 ＞ 0.9). Hence, this model can be applied in practice.
Key words: Gynura bicolor DC.; phytic acid; preservation; quality; mathematical model
采后纳米材料包装结合气调处理对紫背天葵贮藏品质的影响及数学模型建立
姜 丽1，冯 莉1，侯田莹2，郁志芳1
（1.南京农业大学食品科技学院，江苏 南京 210095；2.北京市农林科学院蔬菜研究中心，北京 100097）
摘  要：以紫背天葵为试材，采用纳米材料自发气调、HDPE袋(15 μm厚)人工气调（3% O2）和纳米材料结合人
工气调（3% O2）包装处理，并置于0 ℃条件下贮藏20 d，每5 d测定一次生理指标，包括腐烂率、呼吸强度及叶绿
素、花青素、还原糖、总糖、氨基酸、蛋白质含量。结果表明，纳米结合人工气调包装处理组可有效保持采后紫背
天葵的叶绿素和花青素含量，保持良好的外观色泽，通过延缓花青素、还原糖、总糖、氨基酸和蛋白质含量的下
降，有效保持品质，延缓衰老。建立的一元回归方程为：腐烂率/%=24.605－0.020X7＋1.122X4－0.162X5（式中：X4
为还原糖含量；X5为花青素含量；X7为叶绿素含量），拟合度较好(R
2＞0.9)，可应用于生产实践。
关键词：紫背天葵；纳米材料结合气调包装；贮藏；品质；数学模型
中图分类号：TS255.3 文献标志码：A 文章编号：1002-6630（2014）16-0238-06
doi:10.7506/spkx1002-6630-201416046
收稿日期：2014-05-12
基金项目：国家自然科学基金青年科学基金项目（31301576）；中央高校基本科研业务费专项资金项目（KJQN201428；KYZ201319）
作者简介：姜丽（1982—），女，讲师，博士，研究方向为食品科学。E-mail：jiangli@njau.edu.cn
Gynura bicolor DC. (G. bicolor), a cultivated leafy
vegetable, belongs to the genus Gynura Cass and is used as
food throughout Asia for centuries[1]. It is mostly produced in
southern China and has once been used as a Chinese herbal
medicine[2]. Recently, many Chinese have a deep-rooted
belief that ‘even tastes bad, a well-selected Chinese herbal
medicine uptake from daily diet provides health benefits and
prevents diseases as a tonic’ [3]. Thus, the production and
consumption of G. bicolor have been expanding rapidly.
Since living organisms (water content >90%) with
high metabolic activity after harvest are prone to losing
nutrients and appearance during senescence, proper post-
harvest treatments are in need for G. bicolor production.
Heat treatment, edible coating, high-pressure processing,
refrigerated storage and controlled atmosphere (CA) storage
have been used for vegetables, but the protocols are not
universal. Up to now, the studies on G. bicolor have focused
on nutritional value, antioxidant activity[4], as well as
※包装贮运 食品科学 2014, Vol.35, No.16 239
extracted anthocyanin[5] and flavonoids[6]. In contrast, eligible
preservation technologies have only been reported by our
group during the last 6 years. A previous research showed
that package in combination with low temperature (0 ℃)
improved the nutritional quality of G. bicolor and decre ased
the decay rate to 10% on Day 20[1].
Low-level O2
can delay senescence by significantly
increasing antioxidant activity and total phenolic content,
thus extending the storage life of fresh product[7]. Nano-
packaging (NP) materials, which have better barrier,
mechanical and fresh-keeping properties than normal ones[8-9],
have been applied in a wide range of industries and markets.
Huang Yuanyuan et al.[9] reported that NP better retained VC,
chlorophyll, polyphenol and amino acids in green tea than
normal packaging did. Li Hongmei et al.[8] also reported that
the quality of Ziziphus jujuba Mill. was improved with NP
preservation agents.
Although both CA storage[10] and NP[8-9,11] have been
employed to extend the shelf-life of many vegetables, the
two methods have never been combined. Our previous
studies have shown that CA (3% O2) could effectively delay
the senescence of G. bicolor and maintain good quality.
The objective of this work was to investigate the effect of
combined NP and CA on the nutritional quality of G. bicolor
during storage at 0 ℃, and to establish a mathematical model
describing the storage process.
1 Materials and Methods
1.1 Materials
G. bicolor samples were harvested in a commercial
farmland in Shanghai, China. Then they were pre-cooled to
2–5 ℃ and transferred to the laboratory by a refrigerated
vehicle immediately. The unified leaves were divided
randomly into three groups and treated as follows: 1) Nano-
material-packaging with modified atmosphere (NP, 30 bags
× 600 g/bag); 2) normal polyethylene-packaging with a
controlled atmosphere of 3% O2 and 97% N2 (controlled
CO2＜1%) (CA, 30 bags×600 g/bag); 3) nano-material-
packaging combined with controlled atmosphere of 3% O2
and 97% N2 (controlled CO2＜1%) (CA + NP, 30 bags×600
g/bag). Then all bags were stored at 0 ℃ for 20 days. The
nutritional qualities of three bags from each treatment were
randomly analyzed on the 0, 5th, 10th and 20th days during
storage. The gas compositions for CA and CA+NP were
continuously controlled constant throughout the storage.
The nano-material bags, which contained 10.5% nano-
Ag and 12% nano-TiO2, were 40 µm in thickness and 30 cm×
45 cm in size. Polyethylene bags with the same thickness and
size without nano-powders were employed as controls.
1.2 Decay index
About 500 g leaves from each treatment were used, and
decay degrees were visibly divided into four levels: 0, no decay;
1, decay ＜ l/3; 2, 1/3–2/3 decay; 3, decay＞ 2/3. Decay index
was calculated according to the following formula:
Decay index/% = [(1 × N1 + 2 × N2 + 3 × N3) × 100 / (3 × N)]
where N is the total number of leaves showing different
degrees of decay.
1.3 Respiratory rate
The respiratory rate of G. bicolor was determined
with the small skep method based on CO2 absorption and
expressed as mg CO2/(kg·h)
[1]. A glass plate containing 20 mL
of 0.4 mol/L NaOH was added to absorb CO2 produced by
300 g G. bicolor leaves during respiration. After 1 h, NaOH
was transferred into a beaker and titrated with 0.2 mol/L
oxalic acid.
1.4 Anthocyanin content
The total anthocyanin content was determined by a
spectrophotometric method described by Dourtoglou et
al.[10]. An aliquot of extract was diluted 1:10 with ethanolic
HCl solution (0.25 mol/L). The solution was mixed
thoroughly, and the absorbance at 520 nm (A520 nm) was
read after 5 min, using the ethanolic HCl solution as blank.
Cyanidin 3-glucoside (kuromanin chloride, Rotichrom®) was
used as the standard substance.
1.5 Chlorophyll content
The chlorophyll content was measured by using acetone
colorimetry method with slight modifications[9]. Leaves (0.5 g)
were fully ground, to which acetone ethanol solution (2:1, V/V)
was then added until the constant volume of 25 mL. Then the
absorbance at 652 nm (A652 nm) was detected. Total chlorophyll
content was calculated using Lichtenthaler’s equations.
1.6 Protein and reducing sugar contents
Leaves (0.5 g) were homogenized in distilled water
(6 mL) and centrifuged at 10 000 ×g for 10 min at 4 ℃.
Proteins in the supernatant were determined according
to the method of Bradford[12] with bovine serum albumin
as standard. The amount of released reducing sugar was
determined using the 3,5-dinitrosalicylate (DNS) reagent
method with glucose as reference[11].
1.7 Total carbohydrate and amino acid contents
Total carbohydrate and amino acid in 1 g leaves were
240 2014, Vol.35, No.16 食品科学 ※包装贮运
extracted twice by hot distilled water (10 mL and 1 h each
time) until the constant volume of 25 mL. The supernatant
was used for test. Total carbohydrate content was detected
according to the anthrone colorimetric method described by
Pons et al.[13]. Amino acid content was measured according to
the ninhydrin method[9].
The contents of anthocyanin, chlorophyll, protein, amino
acid, total carbohydrate and reducing sugar were all determined
as milligrams of equivalents per g of fresh weight (FW).
1.8 Statistical analysis
All the treatments and measurements were set up in a
completely randomized factorial design with three replicates.
All data were subjected to the analysis of variance (ANOVA)
with SPSS 18.0 statistical software. A probability of ＜0.05
was considered as significant.
2 Results and Analysis
2.1 Respiratory rate and decay index
Respiration is an important metabolic process that
provides energy for plants, during which various substrates
for key synthetic metabolic pathways are produced. During
storage at 0 ℃, all three treatments increased the respiratory
rate consistently, with the largest increase for CA (from 20.04
mg/(kg·h) to 56.61 mg/(kg·h), almost tripled as original) and
the smallest for CA+NP (from 20.04 mg/(kg·h) to 41.27
mg/(kg·h), doubled as original) (Table 1). NP inhibited the
respiration of G. bicolor more evidently than CA did, and
CA+NP reduced the respiration most effectively and managed
to maintain good quality as well. In contrast, the respiratory
rate of green celery stored in CA decreased during storage[14].
Vegetables decay following browning, yellowing and
putrescence. Browning of fresh vegetables during storage
often leads to quality loss, and thus has become one of the
important factors responsible for short shelf-life and limited
marketability[15-16]. In this study, samples lost weight and
browning was aggravated because the relative humidity
of each treatment was more than 94%. The decay of
G. bicolor leaves was only indicated by browning during
low-temperature storage. As shown in Table 1, all treatments
increase the decay indices of leaves during storage. The
leaves stored in CA started decaying on Day 1 and peaked
(9.64%) on Day 20. Meanwhile, NP and CA+NP groups were
less prone to decay during storage, with the decay indices
(9.23% and 8.97%) significantly lower than that of the CA
group on Day 20 (P ＜ 0.05). In contrast to NP treatments,
combining NP with CA could inhibit leaf decaying
(8.97%) more effectively, which may be related to
the better maintenance of cell membrane integrity
that enhanced the resistance of leaves to infection
and lesion. Similarly, different packages significantly
changed the decay indices of Flammulina velutipes [17].
Li Hongmei et al.[8] also found that nano-Ag, which was
antibacterial, relieved the decay.
Table 1 Effects of NP in combination with CA on decay index,
respiration rate, anthocyanin and chlorophyll contents of G. bicolor
Testing index Treatment
Storage time /d
0 5 10 15 20
Decay index/%
CA 0Ae 2.96±0.11Ad 3.78±0.09Ac 6.02±0.09Ab 10.21±0.20Aa
NP 0Ae 2.72±0.09Bd 3.17±0.9Bc 5.22±0.10Bb 9.95±0.12Ba
CA+NP 0Ae 2.13±0.05Cd 3.46±0.07Cc 5.37±0.09Cb 8.87±0.10Ca
Respiration
rate/
(mg CO2/
(kg·h))
CA 20.04±0.33Ae 28.85±0.21Bd 47.42±1.77Bb 32.27±1.69Bc 56.61±0.69Aa
NP 20.04±0.33Ad 26.66±0.22Cc 29.27±0.22Cb 27.29±0.32Cc 50.04±0.28Ba
CA+NP 20.04±0.33Ac 25.31±0.15Cb 25.52±1.86Db 24.02±0.27Db 41.27±0.35Ca
Anthocyanin
content/
(mg/g )
CA 6.82±0.02Ad 9.57±0.03Cb 11.53±0.21Ca 8.69±0.15Cc 6.42±0.01De
NP 6.82±0.02Ae 10.78±0.26Bb 12.16±0.17Ba 9.54±0.06Bc 7.61±0.02Bd
CA+NP 6.82±0.02Ae 11.09±0.17Ab 13.35±0.15Aa 10.25±0.14Ac 8.17±0.04Ad
Anthocyanin
content/
(mg/g )
CA 1.26±0.02Aa 1.22±0.02Ab 1.15±0.02Cc 1.10±0.01Cd 0.97±0.01Be
NP 1.26±0.02Aa 1.20±0.01Bb 1.13±0.02Cc 1.07±0.02Cd 0.96±0.01Be
CA+NP 1.26±0.02Aa 1.24±0.02Aa 1.20±0.01Bb 1.15±0.01Bc 1.03±0.01Ad
Note: Each value is the mean for three replicates and vertical bars indicate
the standard deviation of each mean value (n = 3). Mean ± SD within the
same column or row followed by the same uppercase or lowercase letter are
not significantly different (LSD 0.05/0.01). Data are analyzed with SPSS.
CA: controlled atmosphere packaging; NP: nano-packaging in combination
with modified atmosphere; CA+NP: nano-packaging in combination with
controlled atmosphere. Different letters in the same column or row indicate
significant difference at the 0.05 level. Table 2 is same.
2.2 Anthocyanin and chlorophyll contents
As a main attribute of most vegetables, color plays a
key role in food choice, preference and acceptability, and
may even influence taste thresholds, sweetness perception
and pleasantness[18]. Since the back of G. bicolor leaves was
purple and the other parts were green, color mainly indicated
the contents of anthocyanin and chlorophyll.
The content of anthocyanin in the leaves of the CA+NP
group increased, decreased, and reached maximum on Day
10. Individual CA and NP treatments exerted similar effects,
but the contents were lower on the same day and reached
significant difference (Table 1). These results suggested
that combining NP with CA maintained stable anthocyanin
content and the purple color more effectively.
All treatments decreased the chlorophyll content
continuously but with slight differences (Table 1). The
※包装贮运 食品科学 2014, Vol.35, No.16 241
chlorophyll contents resembled after CAP and NP treatments,
but there were significant differences between CA+NP and
NP or CAP treated leaves. Hence, CA+NP could keep the
chlorophyll content at a higher level. Similarly, Huang Yuanyuan
et al.[9] reported that the chlorophyll content in green tea with NP
was 6.9% higher than that with normal packaging.
Many crops, such as Brassica, generate anthocyanin
as a stress response indicating poor quality[19]. Higher-level
anthocyanin was induced in response to storage condition
in all groups during the first ten days, and then anthocyanin
degraded responding to senescence. Oxidation converted
chlorophyll into pheophytin, so the chlorophyll content of
G. bicolor leaves steadily decreased during storage. CA+NP
maintained the color of G. bicolor better by inhibiting the
decreases of anthocyanin and chlorophyll.
2.3 Amino acid and protein contents
Amino acid in G. bicolor treated with CA+NP during the
20-day storage increased from 7.64 mg/g on 0 day to 10.02 mg/g
on the 10th day and thereafter decreased to 8.30 mg/g on
the 20th day (Table 2). CA and NP treatments changed the
contents of amino acids similarly and moderately, but the
contents on the 20th day were significantly lower than that
after CA+NP treatment, i.e. 9.08 mg/g on the 10th day and
6.64 mg/g on the 20th day for NP, and 7.09 mg/g on the 10th
day and 6.39 mg/g on the 20th day for CA. Contrarily, Huang
Yuanyuan et al.[9] reported that the amino acid content of
green tea could be retained by using NP. Hence, CA+NP
kept higher amino acid content of G. bicolor leaves. Table 2
presents that the anthocyanin and amino acid contents that are
significantly positively correlated change similarly. However,
the relationship between them remained unclear.
Moreover, the contents of protein in G. bicolor leaves
kept decreasing to minimum on the 20th day of storage. The
protein contents decreased from 9.79 mg/g to 8.41 mg/g for
CA, to 8.94 mg/g for NP and to 9.26 mg/g for CA+NP on
Days 20. CA+NP significantly delayed the decrease in protein
content, which may be ascribed to NP material and combined
CA treatment. Accordingly, nanoparticles could maintain the
protein content at a higher level[17].
The degradation rate of protein exceeded the synthetic
rate, which thus decreased the protein content and probably
increased the amino acid content. However, the amino acid
contents of G. bicolor steadily decreased in all treatments
owing to the enhanced respiration under low O2 condition.
Table 2 Effects of NP in combination with CA on the postharvest
contents of amino acid, protein, total carbohydrate and
reducing sugar in G. bicolor
Testing index Treatment
Storage time/d
0 5 10 15 20
Amino acid
content/
(mg/g )
CK 7.64±0.03Ab 6.46±0.09Cd 8.13±0.12Ca 7.17±0.13Cc 5.99±0.03Ce
CA 7.64±0.03Aa 7.46±0.10Bab 7.09±0.11Dbc 6.90±0.10Cc 6.39±0.03Bd
NP 7.64±0.03Ac 6.77±0.13Cd 9.08±0.10Ba 8.92±0.10Bb 6.64±0.27Bd
CA+NP 7.64±0.03Ae 8.78±0.13Ac 10.02±0.14Aa 9.43±0.07Ab 8.30±0.11Ad
Protein
content/
(mg/g )
CK 9.79±0.03Aa 8.97±0.05Db 8.02±0.03Dc 7.82±0.05Dd 7.53±0.03De
CA 9.79±0.03Aa 9.50±0.06Cb 8.95±0.04Cc 8.67±0.02Cd 8.41±0.07Ce
NP 9.79±0.03Aa 9.58±0.01Bb 9.43±0.08Bc 9.24±0.02Bd 8.94±0.08Be
CA+NP 9.79±0.03Aa 9.76±0.03Aa 9.65±0.04Ab 9.48±0.02Ac 9.26±0.04Ad
Total
carbohydrate
content/
(mg/g )
CK 15.25±0.08Aa 12.55±0.11Db 12.68±0.09Bb 11.54±0.07Dc 9.87±0.08Bd
CA 15.25±0.08Aa 14.05±0.10Bb 12.78±0.07Bc 11.89±0.07Cd 9.37±0.11Ce
NP 15.25±0.08Aa 13.35±0.14Cb 12.20±0.04Cc 12.09±0.10Bd 8.64±0.07De
CA+NP 15.25±0.08Aa 14.67±0.15Ab 13.49±0.13Ac 12.68±0.05Ad 10.34±0.10Ae
Reducing sugar
content/
(mg/g )
CK 1.89±0.02Ad 1.98±0.03Bc 2.11±0.08Cc 3.12±0.05Ca 2.95±0.07Db
CA 1.89±0.02Ad 2.85±0.02Ac 3.21±0.08Bb 3.19±0.05Cb 3.35±0.03Ca
NP 1.89±0.02Ae 2.85±0.03Ad 3.07±0.04Bc 3.36±0.03Bb 3.49±0.04Ba
CA+NP 1.89±0.02Ae 2.86±0.03Ad 3.49±0.04Ac 3.80±0.02Aa 3.64±0.02Ab
2.4 Total carbohydrate and reducing sugar contents
Total carbohydrate in G. bicolor leaves decreased during
storage and reached to 9.37 mg/g for CA, 8.64 mg/g for NP
and 10.34 mg/g for CA+NP on Day 20 (Table 2). There were
significant differences between the three treatments. Being
consistent with the results of Yu Wenhua et al.[20], CA+NP
remarkably retarded the dehydration and gave rise to quality loss.
The overall contents of reducing sugar in G. bicolor
leaves of three treatments all increased during storage and
reached maximum on Day 20, and CA+NP treatment led to
the highest content compared with other two treatments did at
each time point (Table 2). Thus, CA+NP treatment inhibited
the metabolism of reducing sugar from respiratory processes
and then kept quality better.
Moreover, total carbohydrate and reducing sugar
contents were significantly negatively correlated. A part of
reducing sugars originated from the soluble ones released
during storage, probably due to the hydrolysis of total
carbohydrate.
2.5 Establishment of mathematical model
The correlations between decay index (X1), protein
content (X2), total carbohydrate content (X3), reducing sugar
content (X4), anthocyanin content (X5), respiration rate (X6),
chlorophyll content (X7) and amino acid content (X8) were
analyzed. Most variables were highly correlated, so cluster
and factor analyses were performed.
2.5.1 Hierarchical cluster and discriminant
Cluster and discriminant analyses are the fundamental
242 2014, Vol.35, No.16 食品科学 ※包装贮运
methods for categorization. All the treatment groups at
different storage times (CA0, CA5, CA10, CA20, NP0,
NP5, NP10, NP15, NP20, CA+NP0, CA+NP5, CA+NP10,
CA+NP15 and CA+NP20) were divided into 3-5 clusters
by using hierarchical clustering (Fig.1). The groups could
be divided into three classes, viz., CA0, NP0 and CA+NP0
in cluster 1, CA20, NP20 and CA+NP20 in cluster 3, and
other groups in cluster 2. Accordingly, storage time mainly
affected the quality of G. bicolor. When the groups were
further divided into five classes, CA5, NP5, CA+NP5,
NP10, CA+NP10 NP15 and CA+NP15 were all in cluster
2, indicating that NP and CA+NP treatments influenced
preservation more obviously than CA treatment did and that
packaging was the minor influencing factor.
0
CANP0 3
CANP5 6
CANP15 12
CANP10 9
CANP20 15NP0 2CA0 1CA10 7CA15 10CA5 4NP5 5NP15 11NP10 8CA20 13NP20 14 5 10 15 20 25
Fig.1 Dendrogram using average linkage (between groups) rescaled
distance cluster
Since only storage period (prophase, metaphase and
anaphase) needs to be predicted in practical production,
a discriminant clustering equation was established herein
based on cluster analysis. The coefficients of the equations
are listed below:
This equation had good discrimination ability throughout
G. bicolor storage and could be used to determine the storage
period. The data were assigned to the cluster that scored
highest respectively.
2.5.2 Factor analysis and regressionˉ1.0 ˉ1.0ˉ0.5 ˉ0.50.0 0.00.5 0.51.0 1.0Factor 2
Factor 1
Respiration rate
Reducing suger content
Decay
Anthocyanin content
Amino acid content
Protein content
Total carbothydrate content
Chlorophyll content
Fig.2 Factor plot in rotated factor space
The cumulative contribution rates of the first and
second principal components are 62.210% and 23.805%,
respectively. The first two principal component contribution
rates, which exceeded 85%, were utilized to carry out
subsequent analysis.
A rotated factor model was established by maximum-
variance orthogonal rotation of the original component
matrix. Then two common factors, factor 1 and factor 2, were
extracted as the first and second principal factors respectively.
The first principal factor was mainly determined by decay
index (X1), total carbohydrate content (X3) and chlorophyll
content (X7), and their loads on the main factor were -0.969,
0.978 and 0.981, respectively (Fig.2). The second principal
factor was mainly determined by amino acid content (X8), and
its load on the main factor was 0.994. Therefore, factor 1 and
factor 2 were referred to as quality factor and flavor factor,
respectively. In addition, decay index, respiration rate and
contents of reducing sugar, amino acid, anthocyanin, protein,
chlorophyll and total carbohydrate might change similarly
during G. bicolor senescence (Fig.2). Afterwards, the factor
scores of observable variables were calculated by factor score
coefficients with the equation bellow:
F3＝681.619X1+3 187.018X2-233.198X3-1 588.392X4-
339.378 8X5+73.329X6+9.271X7+71.982X8-18 130.867
F2＝635.444X1+2 925.513X2-197.672X3-1 457.447X4-
311.408X5+66.425X6+8.432X7+56.799X8-15 402.681
F1＝670.776X1+3 185.669X2-238.858X3-1 686.828X4-
378.084X5+72.984X6+9.533X7+94.686X8-17 989.190
As suggested by the scores of all treatment groups at
different storage time points (Fig.3), CA+NP and CA groups
had higher antioxidant capacities, CA+NP and NP groups
had better flavor, and CA+NP group had maximum storage
capacity. 2.0 51.5 100.50.0 0 150.51.51.0 A1.0 20CANPCANPScores Storage time/d1.5 51.0 100.51.0 0 151.52.52.0 B0.50.0 20CANPCANPScores Storage time/d
※包装贮运 食品科学 2014, Vol.35, No.16 2431.5 51.0 100 150.01.00.5 C0.5 20CANPCANPScores Storage time/d
A. score of factor 1; B. score of factor 2; C. score of total.
Fig.3 Factor scores of all treatment groups
Table 3 Coefficientsa
Model
Unstandardized coefficients
Standardized coefficients t Sig.
B Std. Error
(Constant) 32.219 2.105 15.303 0.000
Chlorophyll -0.025 0.002 -0.968 -13.861 0.000
(Constant) 26.793 3.142 8.527 0.000
Chlorophyll -0.022 0.002 -0.859 -10.749 0.000
Reducing sugar -0.723 0.337 0.171 2.145 0.053
(Constant) 24.605 3.049 8.070 0.000
Chlorophyll -0.020 0.002 -0.776 -9.253 0.000
Reducing sugar 1.122 0.367 0.266 3.057 0.011
Anthocyanin -0.162 0.083 -0.133 -1.940 0.078
Note: a. Dependent variable: decay index.
The process was run in three steps (Table 3), and only
X4, X5 and X7 remained in the model in the last step. The
prediction equation was expressed below:
Decay index/%=24.605-0.020X7+1.122X4-0.162X5
Decay index of G. bicolor , as suggested by the
regression equation, was significantly negatively correlated
with chlorophyll and anthocyanin contents, and was positively
correlated with reducing sugar content. The content of
oxygen free radicals increased with prolonged storage. In the
meantime, chlorophyll, anthocyanin and reducing sugar were
easily oxidized[21], and the oxidation of them or the retention
rate was able to reflect the senescence process. R2＞0.9,
F statistic is 103.749, and the significance level of automatic
system test is 0.000 1, suggesting that the equation allowed
better fitting and gave very significant difference. Therefore,
this regression equation can be applied to production practice.
3 Conclusions
In summary, NP in combination with CA exerted
significant beneficial effect on the quality maintenance of
G. bicolor than each applied separately did. The leaves
of treated G. bicolor had higher antioxidant capacity, as
evidenced by the high contents of chlorophyll, anthocyanin
and reducing sugars. Hence, the senescence of G. bicolor
leaves was delayed during storage. The mathematical
models for predicting the storage duration and the decay of
G. bicolor were established respectively, both being
applicable to practice use.
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