施氮量對(duì)甘薯塊根膨大過(guò)程中淀粉含量及特性的影響

吳世雨 陳匡稷 呂尊富 徐錫明 龐林江 陸國(guó)權(quán),*

施氮量對(duì)甘薯塊根膨大過(guò)程中淀粉含量及特性的影響

吳世雨1,2陳匡稷1,3呂尊富1,2徐錫明1,2龐林江2,4陸國(guó)權(quán)1,2,*

1浙江農(nóng)林大學(xué)現(xiàn)代農(nóng)學(xué)院/浙江省農(nóng)產(chǎn)品品質(zhì)改良重點(diǎn)實(shí)驗(yàn)室, 浙江杭州 311300;2浙江農(nóng)林大學(xué)薯類作物研究所, 浙江杭州 311300;3儀征市農(nóng)業(yè)技術(shù)綜合服務(wù)中心, 江蘇揚(yáng)州 211400;4浙江農(nóng)林大學(xué)食品與健康學(xué)院, 浙江杭州 311300

為探究施氮量對(duì)甘薯塊根膨大過(guò)程中淀粉含量及特性的影響, 以‘心香’和‘商薯19’為試驗(yàn)材料, 設(shè)置0 kg hm–2(CK)、57.5 kg hm–2(N1)、115 kg hm–2(N2) 3個(gè)氮肥(N)處理在栽插當(dāng)日施用。在栽插后60、80、100、120和140 d取樣, 研究了施加氮肥后甘薯塊根膨大過(guò)程中淀粉的含量、糊化特性、流變特性、凝膠質(zhì)構(gòu)特性及淀粉酶活性的變化規(guī)律。結(jié)果表明, (1) 在塊根膨大過(guò)程中, 施用氮肥可顯著提高2個(gè)甘薯品種淀粉含量。塊根膨大前期施氮顯著降低‘心香’淀粉糊化特性的最低黏度、最終黏度和消減值, 后期顯著降低‘商薯19’淀粉糊化特性的最低黏度、最終黏度和消減值, 顯著提高‘心香’淀粉糊化特性的最低黏度、最終黏度和消減值; (2) 3個(gè)處理下, 淀粉凝膠硬度和咀嚼性隨塊根的膨大逐漸降低。在塊根膨大后期, N2處理可顯著提升2個(gè)品種的淀粉凝膠硬度; (3) 2個(gè)品種淀粉凝膠呈現(xiàn)彈性性質(zhì), N1、N2處理可提高‘心香’的儲(chǔ)能模量和損耗模量, 降低‘商薯19’的儲(chǔ)能模量和損耗模量; (4)塊根膨大前期, 施氮降低2個(gè)品種α-淀粉酶和β-淀粉酶活性, 但是塊根膨大后期提高。因此, 施氮量會(huì)對(duì)甘薯塊根膨大過(guò)程中淀粉含量及特性產(chǎn)生顯著影響?！淌?9’在115 kg hm–2施氮量下, 栽插后120 d時(shí)進(jìn)行收獲, 有利于甘薯淀粉加工。合理施氮、適時(shí)收獲有利于甘薯淀粉的積累及其品質(zhì)提升。

甘薯; 氮肥; 塊根膨大期; 淀粉; 理化特性

甘薯((L.) Lam.)是重要的糧食、飼料、工業(yè)原料等, 在世界糧食生產(chǎn)中總產(chǎn)列第7位, 在中國(guó)糧食與能源安全中具有重要作用[1]。甘薯因其光合能力強(qiáng), 單位面積的淀粉產(chǎn)量高于一般谷類作物, 已成為生產(chǎn)淀粉的主要原料作物[2]。淀粉是甘薯塊根的主要成分之一, 占?jí)K根干物質(zhì)含量的50%～80%[3-4]。甘薯可用作鮮食、淀粉加工、食品加工等, 其中甘薯淀粉廣泛用于面條、粉條、焙烤食品、糖果產(chǎn)品等方面[5-6]。

甘薯淀粉的理化特性主要受遺傳因素控制, 環(huán)境也會(huì)對(duì)其產(chǎn)生影響[7]。氮是甘薯生長(zhǎng)發(fā)育期間所必需的大量營(yíng)養(yǎng)元素[8]。適量施氮可有效提高甘薯塊根產(chǎn)量[9]。王良平等[10]研究結(jié)果表明土壤中氮含量對(duì)甘薯塊根的淀粉率產(chǎn)生極顯著影響。陳曉光等[7]研究表明施氮使‘徐薯22’和‘徐薯28’品種塊根的淀粉最高黏度、最低黏度、最終黏度和消減值等特征值升高, 且施氮量對(duì)淀粉RVA譜特征值的影響因品種的不同而有差異。黃華宏等[11]研究了不同生育期甘薯塊根淀粉糊化特性的差異, 發(fā)現(xiàn)‘徐薯18’、‘浙大9201’和‘浙3449’ 3個(gè)甘薯品種在生育期內(nèi), 淀粉率都呈下降趨勢(shì), 隨生育期延長(zhǎng), RVA的最高黏度呈現(xiàn)遞增趨勢(shì)。李臣等[12]以鮮食甘薯代表性品種‘心香’為試驗(yàn)材料, 對(duì)其進(jìn)行生育期內(nèi)的營(yíng)養(yǎng)成分及加工特性指標(biāo)變化規(guī)律和相關(guān)性分析, 發(fā)現(xiàn)生育期119 d的淀粉率最高, 適合淀粉加工。

氮肥對(duì)作物淀粉品質(zhì)的影響在小麥[13]、水稻[14]等主要作物上已有了大量的研究, 同時(shí)在與甘薯相似的作物馬鈴薯[15]上也有了大量研究, 目前對(duì)甘薯的研究大多集中收獲時(shí)產(chǎn)量、淀粉含量及其特性方面, 對(duì)于甘薯塊根膨大期淀粉特性的影響涉及較少。本研究以鮮食型品種‘心香’和淀粉型品種‘商薯19’為試驗(yàn)材料, 設(shè)置3個(gè)氮肥(N)處理, 從甘薯塊根膨大期的淀粉含量、糊化特性、動(dòng)態(tài)流變特性、質(zhì)構(gòu)特性及淀粉酶活性方面探討施氮量對(duì)不同品種甘薯塊根淀粉含量及特性影響, 以期為甘薯淀粉食品加工生產(chǎn)提供優(yōu)質(zhì)原料, 為氮肥科學(xué)施用提供理論基礎(chǔ)。

1 材料與方法

1.1 試驗(yàn)材料與設(shè)計(jì)

本試驗(yàn)于2020年在浙江農(nóng)林大學(xué)農(nóng)作園基地進(jìn)行, 甘薯選用淀粉型品種‘商薯19’ (河南省商丘市農(nóng)林科學(xué)院選育, 淀粉率21%以上)和鮮食型品種‘心香’ (浙江省農(nóng)林科學(xué)院培育, 淀粉率22.1%), 氮肥采用尿素(N含量46%)、磷肥采用過(guò)磷酸鈣(P2O5含量16%)、鉀肥采用硫酸鉀(K2O含量51%)。供試土壤類型為紅壤土, 0～20 cm土層土壤含全氮0.82 g kg–1、全磷0.61 g kg–1、全鉀25.8 g kg–1、速效氮55.42 mg kg–1、速效磷6.70 mg kg–1、速效鉀218.97 mg kg–1。

設(shè)置0 kg hm–2(CK)、57.5 kg hm–2(N1)、115 kg hm–2(N2) 3個(gè)氮肥(N)處理, 各處理的磷肥(P2O5)用量均為120 kg hm–2, 鉀肥(K2O)用量均為300 kg hm–2, 種植前統(tǒng)一施肥。小區(qū)面積36 m2(6 m×6 m), 每個(gè)小區(qū)6壟, 重復(fù)3次, 壟寬85 cm, 高25 cm, 壟間距1 m, 株距20 cm, 于2020年5月28日栽插, 于2020年10月17日收獲, 在栽插后60、80、100、120和140 d進(jìn)行取樣。對(duì)所有的小區(qū)進(jìn)行覆蓋地膜處理, 水源為雨水自然灌溉。統(tǒng)一種植, 保證甘薯的種植周期、光照及管理措施等條件一致。

1.2 測(cè)定項(xiàng)目與方法

1.2.1 淀粉提取 淀粉提取參照唐忠厚等[16]的方法并稍做修改。淀粉制備: 薯塊去皮, 切成細(xì)塊狀,放入高速打漿機(jī), 加適量水, 粉碎30 s, 倒入100目紗袋, 加0.5 L水洗提, 另0.5 L水再洗提一次, 將洗提液合并, 過(guò)100目篩, 靜置12 h, 置40℃空氣干燥機(jī)中干燥24 h, 研磨成粉末, 過(guò)100目篩, 密封, 干燥避光條件保存。

1.2.2 甘薯全粉制備 選取3～5個(gè)大小一致、無(wú)病蟲(chóng)害、無(wú)破損的薯塊, 洗凈晾干, 用切片機(jī)切成0.2 cm的薄片, 液氮迅速浸泡20 min后, 轉(zhuǎn)移至冷凍干燥機(jī)中, 進(jìn)行–80℃冷凍干燥72 h, 干燥后用錘式旋風(fēng)磨磨成粉狀, 過(guò)100目篩, 密封, 低溫干燥避光條件保存。

1.2.3 淀粉含量測(cè)定 采用鹽酸水解DNS法[17]。

1.2.4 淀粉的糊化特性測(cè)定 參照包勁松[18]的方法測(cè)定淀粉的糊化特性, 參照美國(guó)谷物協(xié)會(huì)(AACC)76-21方法[19], 采用升溫-降溫循環(huán)程序。

1.2.5 淀粉凝膠的質(zhì)構(gòu)特性測(cè)定 參照Bao等[20]的方法。

1.2.6 淀粉凝膠的動(dòng)態(tài)流變特性測(cè)定 參照Sandhu等[21]的方法。

1.2.7 淀粉酶活性測(cè)定 參照曹建康[22]試驗(yàn)方法。

1.3 數(shù)據(jù)處理與分析

采用Microsoft Excel 2016軟件進(jìn)行試驗(yàn)數(shù)據(jù)的錄入和整理, 采用SPSS 23和Origin 8.6軟件進(jìn)行數(shù)據(jù)分析, 采用Duncan’s多重比較法進(jìn)行方差分析, 采用spearman相關(guān)性分析法進(jìn)行相關(guān)性分析, 采用Microsoft Excel 2016和Origin 8.6軟件繪圖。

2 結(jié)果與分析

2.1 施氮對(duì)甘薯塊根膨大過(guò)程中淀粉含量的影響

由圖1可知, 施氮可顯著提高2個(gè)品種的淀粉含量, N2處理提高淀粉含量效果更顯著?！南恪韷K淀粉含量在塊根膨大期呈現(xiàn)出先升高后降低的整體趨勢(shì), 在栽插后100 d達(dá)到最大值, 分別為79.54%、81.54%、84.19%。N1處理下, 薯塊淀粉含量在栽插后60、100、120 d顯著高于CK組, 在栽插后80、140 d顯著低于CK組; N2處理下, 薯塊淀粉含量在塊根膨大期間顯著高于CK組。‘商薯19’塊根淀粉含量在塊根膨大期呈現(xiàn)上下波動(dòng)的變化, 這與周志林等[23]的研究結(jié)果相一致。CK、N1處理下, 栽插后100 d出現(xiàn)淀粉含量最大值, 分別是67.56%、69.39%; N2處理下, 栽插后60 d淀粉含量最高, 為73.33%。

2.2 施氮對(duì)甘薯塊根膨大過(guò)程中淀粉糊化特性的影響

由表1和表2可知, 施氮對(duì)2個(gè)品種的淀粉糊化特性具有顯著影響, 其中對(duì)最低黏度、崩解值、最終黏度、消減值的影響最大。由表1可知, 與CK處理相比較, 栽插后60～100 d, N1、N2處理顯著降低最低黏度; 栽插后120 d, N1、N2處理下最低黏度大于CK處理但無(wú)顯著差異; 栽插后140 d, N1、N2處理顯著提升最低黏度; 在塊根膨大過(guò)程中, N1、N2處理間最低黏度無(wú)顯著差異。崩解值用于測(cè)量淀粉糊的耐熱性, 栽插后60～80 d, N1、N2處理顯著提升淀粉的崩解值; 栽插后100～140 d, CK、N2處理間崩解值差異顯著。N1、N2處理下最終黏度在栽插后60～100 d顯著低于CK處理, 在栽插后100 d, 顯著高于CK處理。消減值等于最終黏度減最高黏度, 栽插后60～120 d, N1、N2處理消減值顯著低于CK, 栽插后140 d, 顯著高于CK處理。栽插后60～80 d, N2處理顯著降低峰值時(shí)間, 峰值時(shí)間在塊根膨大后期差異不顯著。糊化溫度僅在栽插后140 d時(shí), N1、N2處理顯著高于CK其余時(shí)期, 差異不顯著。

由表2可知, 栽插后60 d, 3個(gè)處理間淀粉糊化特性指標(biāo)無(wú)顯著差異。與CK處理相比較, 栽插后80 d, N2處理顯著提高淀粉糊化溫度; 栽插后100 d, N1處理顯著提高最高黏度和崩解值, 顯著降低消減值, N2處理顯著降低最低黏度; 栽插后120 d, N2處理顯著提高最高黏度和崩解值; 栽插后140 d, N1處理顯著降低最高黏度、最低黏度、最終黏度、消減值、峰值時(shí)間和糊化溫度, N2處理顯著提升最高黏度和崩解值, 顯著降低最低黏度、最終黏度、消減值、峰值時(shí)間及糊化溫度。

圖1 不同施氮量對(duì)甘薯塊根膨大過(guò)程中淀粉含量的影響

A: 心香; B: 商薯19。CK: 0 kg hm–2氮肥施用量; N1: 57.5 kg hm–2氮肥施用量; N2: 115 kg hm–2氮肥施用量。不同小寫字母標(biāo)識(shí)代表不同處理在同一時(shí)期差異顯著(< 0.05)。

A: Xinxiang; B: Shangshu 19. CK: 0 kg hm–2of nitrogen fertilizer application rate; N1: 57.5 kg hm–2of nitrogen fertilizer application rate; N2: 115 kg hm–2of nitrogen fertilizer application rate. Different lowercase letters indicate that the different treatment is significant differences in the same periods at< 0.05.

表1 不同施氮量對(duì)‘心香’塊根膨大過(guò)程中淀粉糊化特性的影響

處理同圖1。不同小寫字母標(biāo)識(shí)代表不同處理在同一時(shí)期差異顯著(< 0.05)。

Treatments are the same as those given in Fig. 1. PKV: peak viscosity; HPV: hot paste viscosity; BDV: breakdown viscosity; CPV: cold paste viscosity; SBV: setback viscosity; T: peak time; PT: pasting temperature. Different lowercase letters indicate that the different treatment is significant differences in the same periods at< 0.05.

表2 不同施氮量對(duì)‘商薯19’塊根膨大過(guò)程中淀粉糊化特性的影響

處理同圖1。不同小寫字母標(biāo)識(shí)代表不同處理在同一時(shí)期差異顯著(< 0.05)。

Treatments are the same as those given in Fig. 1. PKV: peak viscosity; HPV: hot paste viscosity; BDV: breakdown viscosity; CPV: cold paste viscosity; SBV: setback viscosity; T: peak time; PT: pasting temperature. Different lowercase letters indicate that the different treatment is significant differences in same periods at< 0.05.

2.3 施氮對(duì)甘薯塊根膨大過(guò)程中淀粉凝膠質(zhì)構(gòu)的影響

表3和表4為甘薯塊根膨大過(guò)程中, 不同施氮量下淀粉凝膠的質(zhì)構(gòu)參數(shù)變化。塊根膨大過(guò)程中, 2個(gè)品種淀粉凝膠硬度和咀嚼性呈逐漸降低的趨勢(shì), 黏聚性和回復(fù)性則呈現(xiàn)波動(dòng)的趨勢(shì)。不同施氮量對(duì)‘心香’塊根膨大過(guò)程中淀粉凝膠的硬度影響最大, 對(duì)‘商薯19’塊根膨大過(guò)程中淀粉凝膠的硬度和咀嚼性影響最大。由表3可知, 與CK處理相比較, 栽插后60～80 d, N1、N2顯著降低‘心香’淀粉凝膠硬度; 栽插后100～120 d, 各處理間無(wú)顯著差異; 栽插后140 d, N1、N2處理顯著提高硬度。由表4可知, N2處理在栽插后80、120和140 d顯著提升‘商薯19’淀粉凝膠硬度和咀嚼性, N1處理在栽插后100 d顯著提升淀粉凝膠硬度和咀嚼性, 其他時(shí)期3個(gè)處理間無(wú)顯著差異。

表3 不同施氮量對(duì)‘心香’塊根膨大過(guò)程中淀粉凝膠質(zhì)構(gòu)特性的影響

處理同圖1。不同小寫字母標(biāo)識(shí)代表不同處理在同一時(shí)期差異顯著(< 0.05)。

Treatments are the same as those given in Fig. 1. Different lowercase letters indicate that the different treatment is significant differences in the same periods at< 0.05.

表4 不同施氮量對(duì)‘商薯19’塊根膨大過(guò)程中淀粉凝膠質(zhì)構(gòu)特性的影響

(續(xù)表4)

處理同圖1。不同小寫字母標(biāo)識(shí)代表不同處理在同一時(shí)期差異顯著(< 0.05)。

Treatments are the same as those given in Fig. 1. Different lowercase letters indicate that the different treatment is significant differences in the same periods at< 0.05.

2.4 施氮對(duì)甘薯塊根膨大過(guò)程中淀粉凝膠動(dòng)態(tài)流變特性的影響

不同施氮量處理對(duì)‘心香’與‘商薯19’塊根膨大期的淀粉凝膠動(dòng)態(tài)流變特性如圖2和圖3所示。儲(chǔ)能模量(G′)代表樣品的彈性特性, 損耗模量(G″)代表樣品的黏性特性。G″/G′定義為損耗角正切值(tan δ)。由下圖可知, 隨頻率增大, ‘心香’和‘商薯19’淀粉凝膠的儲(chǔ)能模量和損耗模量值均呈現(xiàn)逐漸增加的整體趨勢(shì); 損耗角正切值整體上呈現(xiàn)先降低后升高的趨勢(shì), 且所有樣品損耗角正切值(tan δ)均小于1, 即G′始終大于G″。甘薯塊根的膨大過(guò)程中, N1、N2處理提升了‘心香’淀粉凝膠的儲(chǔ)能模量和損耗模量, 且提升強(qiáng)度N2>N1, 同時(shí)降低損耗角正切值。對(duì)于‘商薯19’, N1、N2處理降低其儲(chǔ)能模量和損耗模量, 對(duì)損耗角正切值影響不明顯。

2.5 施氮對(duì)甘薯塊根膨大過(guò)程中淀粉酶活性的影響

不同施氮量處理下, ‘心香’和‘商薯19’塊根膨大過(guò)程中α-淀粉酶活性值如圖4所示。在各處理下, 2個(gè)品種的α-淀粉酶活性呈整體上升的趨勢(shì), 在栽插后100 d具有顯著上升變化。栽插后60～80 d, N1、N2處理可顯著降低2個(gè)品種的α-淀粉酶活性。栽插后100～140 d, N1、N2處理可提升2個(gè)品種的α-淀粉酶活性, 對(duì)于‘心香’ N1處理效果更顯著, 對(duì)于‘商薯19’ N2處理效果更顯著。

圖2 不同施氮量對(duì)‘心香’塊根膨大過(guò)程中動(dòng)態(tài)流變特性的影響

CK: 0 kg hm–2氮肥施用量; N1: 57.5 kg hm–2氮肥施用量; N2: 115 kg hm–2氮肥施用量。60、80、100、120和140 d分別代表栽插后60、80、100、120和140 d。

CK: 0 kg hm–2of nitrogen fertilizer application rate; N1: 57.5 kg hm–2of nitrogen fertilizer application rate; N2: 115 kg hm–2of nitrogen fertilizer application rate. 60, 80, 100, 120, and 140 d represent 60, 80, 100, 120, and 140 days after planting, respectively.

圖3 不同施氮量對(duì)‘商薯19’塊根膨大過(guò)程中動(dòng)態(tài)流變特性的影響

處理同圖2。Treatments are the same as those given in Fig. 2.

圖4 不同施氮量對(duì)甘薯塊根膨大過(guò)程中a-淀粉酶活性的影響

A: 心香; B: 商薯19。不同小寫字母標(biāo)識(shí)代表不同處理在同一時(shí)期差異顯著(< 0.05)。處理同圖1。

A: Xinxiang; B: Shangshu 19. Different lowercase letters indicate that the different treatment is significant differences in the same periods at< 0.05. Treatments are the same as those given in Fig. 1.

不同施氮量處理下, ‘心香’和‘商薯19’塊根膨大過(guò)程中β-淀粉酶活性值如圖5所示。在各處理下, 2個(gè)品種β-淀粉酶活性呈現(xiàn)逐漸升高的趨勢(shì), 在栽插后120 d有顯著性增強(qiáng)。栽插后140 d 2個(gè)品種β-淀粉酶活性達(dá)到最大值, 且N2處理的β-淀粉酶活性顯著高于CK組。栽插后60～80 d, 施氮可降低2個(gè)品種的β-淀粉酶活性, 但與CK處理比較差異不顯著。栽插后100～140 d, N1、N2處理可顯著提高2個(gè)品種的β-淀粉酶活性。

2.6 甘薯塊根淀粉主要理化指標(biāo)相關(guān)性分析

相關(guān)分析結(jié)果顯示(表5), 淀粉含量與α-淀粉酶活性、淀粉質(zhì)構(gòu)黏聚性呈顯著正相關(guān), 與RVA糊化溫度呈顯著負(fù)相關(guān), 與淀粉凝膠損耗模量呈極顯著負(fù)相關(guān)。α-淀粉酶活性與淀粉凝膠質(zhì)構(gòu)的硬度呈極顯著負(fù)相關(guān), 與RVA最低黏度呈極顯著正相關(guān), 與咀嚼性、RVA最終黏度、淀粉損耗模量呈顯著負(fù)相關(guān), 與黏聚性、RVA最高黏度呈顯著正相關(guān), α-淀粉酶活性與b-淀粉酶活性呈極顯著正相關(guān)關(guān)系。硬度與RVA最高黏度、崩解值呈極顯著負(fù)相關(guān), 與消減值呈極顯著正相關(guān)。因此, 甘薯塊根淀粉含量及淀粉酶活性與淀粉的糊化特性、流變特性、質(zhì)構(gòu)特性等理化特性密切相關(guān)。

圖5 不同施氮量對(duì)甘薯塊根膨大過(guò)程中β-淀粉酶活性的影響

Fig. 5 Effects of different nitrogen fertilizer application rates on the β-amylase activity during storage root expansion in sweetpotato

A: 心香; B: 商薯19。不同小寫字母標(biāo)識(shí)代表不同處理在同一時(shí)期差異顯著(< 0.05)。處理同圖1。

A: Xinxiang; B: Shangshu 19.Different lowercase letters indicate that the different treatment is significant differences in the same periods at< 0.05.Treatments are the same as those given in Fig. 1.

3 討論

淀粉作為甘薯塊根干物質(zhì)的主要成分之一, 其含量及理化性質(zhì)對(duì)薯塊的產(chǎn)后加工有重要影響, 淀粉含量主要受品種的影響, 同時(shí)也受環(huán)境的影響[24]。柳強(qiáng)娟等[25]研究表明隨著施氮量的增加, 馬鈴薯總淀粉含量呈現(xiàn)先上升后下降的趨勢(shì)。張友良等[26]研究結(jié)果表明, 在相同滴灌濕潤(rùn)比條件下, 淀粉含量隨著施氮量增加而先增加后減小, 180 kg hm-2處理獲得最高的淀粉含量, 適量施加氮肥對(duì)甘薯的生長(zhǎng)有促進(jìn)的效果, 能提高甘薯塊根的干物質(zhì)率。本研究中, N1、N2處理均使2個(gè)品種淀粉含量顯著增大, 和前人研究結(jié)果不一致可能是因?yàn)槠贩N的原因, 導(dǎo)致施氮效果不一樣。對(duì)于鮮食型品種來(lái)說(shuō), 淀粉含量較低, 塊根蒸煮食味較好, 因此施加氮肥更有利于甘薯品種‘商薯19’。a-淀粉酶和b-淀粉酶是參與甘薯塊根中淀粉酶水解最主要的酶, 其活性變化對(duì)甘薯品質(zhì)有著重要的影響[27]。本研究中, α-淀粉酶活性與β-淀粉酶活性呈極顯著正相關(guān)關(guān)系, 施氮可在塊根膨大前期降低2個(gè)品種淀粉酶活性, 后期增強(qiáng)2個(gè)品種淀粉酶的活性。

糊化特性是反應(yīng)淀粉品質(zhì)的重要指標(biāo), 是評(píng)價(jià)甘薯淀粉物理品質(zhì)的重要參數(shù), 對(duì)薯塊食味和加工品質(zhì)有著重要的影響[28]。前人研究認(rèn)為崩解值大、消減值小的稻米食味品質(zhì)優(yōu)[29-30], 本研究中, 施氮處理使‘心香’在塊根膨大后期的淀粉崩解值變小、消減值變大, 使‘商薯19’淀粉崩解值變大、消減值變小, 這說(shuō)明施用氮肥可能會(huì)降低鮮食型品種的食用品質(zhì),提升淀粉型甘薯的食用品質(zhì)。RVA參數(shù)(保持強(qiáng)度、最終黏度、峰黏度、回生值和衰減度) 與粉絲品質(zhì)有顯著的相關(guān)性[31]。俞樹(shù)璽等[32]研究結(jié)果表明, 峰值時(shí)間、糊化溫度與甘薯粉條品質(zhì)呈正相關(guān), 最終黏度與之呈負(fù)相關(guān)。本研究中, 施氮處理對(duì)2個(gè)品種的峰值時(shí)間和糊化溫度影響較小, 在塊根膨大前期顯著降低‘心香’最終黏度, 在塊根膨大后期顯著降低‘商薯19’最終黏度, 這說(shuō)明施用氮肥可能會(huì)提升2個(gè)品種的粉條加工品質(zhì)。

淀粉凝膠的質(zhì)構(gòu)特性可以反映出食品的品質(zhì)特性, 對(duì)于研發(fā)新食品、改善食品的感官性質(zhì)、控制食品品質(zhì)等有重要作用[33]。已有研究表明淀粉濃度和直鏈淀粉含量是影響淀粉凝膠特性的關(guān)鍵參數(shù), 直鏈淀粉含量與淀粉凝膠強(qiáng)度呈正比[34]。本研究中, 淀粉凝膠的硬度隨塊根膨大期的延長(zhǎng)呈現(xiàn)逐漸降低的趨勢(shì), 淀粉酶活性呈現(xiàn)逐漸升高的趨勢(shì), 同時(shí)相關(guān)性分析顯示, 淀粉凝膠的硬度與淀粉酶活性呈極顯著負(fù)相關(guān)的關(guān)系。施氮處理使2個(gè)品種淀粉凝膠的硬度降低, 這可能與直鏈淀粉分子間的相互交聯(lián)程度減弱有關(guān), 進(jìn)而形成了質(zhì)地較柔軟的淀粉凝膠。

動(dòng)態(tài)流變性用來(lái)描述樣品的黏彈性, 對(duì)加工品質(zhì)和質(zhì)量具有很大意義[35]。當(dāng)tan δ>1時(shí), 樣品總體呈現(xiàn)黏性性質(zhì); 反之, 當(dāng)tan δ<1時(shí), 則呈現(xiàn)彈性性質(zhì)[36]。tan δ越大, 凝膠流動(dòng)性強(qiáng), tan δ越小, 固體特性越強(qiáng)。本研究中, 施氮提升了‘心香’淀粉凝膠的流動(dòng)性, 可能與改變淀粉顆粒大小影響了甘薯淀粉的流變性能有關(guān)[37]。本研究中甘薯淀粉凝膠以彈性性質(zhì)為主, 呈現(xiàn)典型的弱凝膠動(dòng)態(tài)流變學(xué)圖譜, 這一結(jié)果與譚洪卓等[38]對(duì)甘薯淀粉凝膠研究結(jié)果相一致。本研究中, 施氮處理提高‘心香’淀粉凝膠的黏彈性, 降低‘商薯19’的黏彈性, 黏彈性更高的淀粉糊, 更適合作為食品加工的輔料和添加劑。

4 結(jié)論

施加氮肥會(huì)對(duì)甘薯塊根膨大過(guò)程中淀粉含量、淀粉酶活性、糊化特性、流變特性、質(zhì)構(gòu)特性產(chǎn)生不同程度影響?！淌?9’在115 kg hm-2施氮量下, 栽插后120 d進(jìn)行收獲, 此時(shí)淀粉含量最高, 淀粉最終黏度低有利于甘薯粉絲加工。合理施氮、適時(shí)收獲有利于甘薯淀粉的積累及其品質(zhì)提升。

[1] 劉慶昌. 甘薯在我國(guó)糧食和能源安全中的重要作用. 科技導(dǎo)報(bào), 2004, (9): 21–22.

Liu Q C. Importance of sweet potato in the security of food and energy in China., 2004, (9): 21–22 (in Chinese with English abstract).

[2] 馬劍鳳, 程金花, 汪潔, 戴紅君, 戴起偉. 國(guó)內(nèi)外甘薯產(chǎn)業(yè)發(fā)展概況. 江蘇農(nóng)業(yè)科學(xué), 2012, 40(12): 1–5.

Ma J F, Cheng J H, Wang J, Dai H J, Dai Q W. Overview of sweet potato industry development at home and abroad., 2012, 40(12): 1–5(in Chinese with English abstract).

[3] Aina A J, Falade K O, Akingbala J O, Titus P. Physicochemical properties of twenty-one Caribbean sweet potato cultivars., 2009, 44: 1696–1704.

[4] Antonio G C, Takeiti C Y, Oliveira R A D, Park K J. Sweet potato: production, morphological and physicochemical characteristics, and technological process., 2011, 5: 914035.

[5] 張令文, 琚星, 李欣欣, 胡新月, 計(jì)紅芳, 畢繼才, 馬漢軍. 8個(gè)品種甘薯淀粉的理化性質(zhì)及其相關(guān)性分析. 食品工業(yè)科技, 2021, 42(4): 26–32.

Zhang L W, Ju X, Li X X, Hu X Y, Ji H F, Bi J C, Ma H J. Physicochemical properties and their correlation of starches from eight sweet potato cultivars., 2021, 42(4): 26–32(in Chinese with English abstract).

[6] 王欣, 李強(qiáng), 曹清河, 馬代夫. 中國(guó)甘薯產(chǎn)業(yè)和種業(yè)發(fā)展現(xiàn)狀與未來(lái)展望. 中國(guó)農(nóng)業(yè)科學(xué), 2021, 54: 483–492.

Wang X, Li Q, Cao Q H, Ma D F. Current status and future prospective of sweet potato production and seed industry in China., 2021, 54: 483–492(in Chinese with English abstract).

[7] 陳曉光, 丁艷鋒, 唐忠厚, 魏猛, 史新敏, 張愛(ài)君, 李洪民. 氮肥施用量對(duì)甘薯產(chǎn)量和品質(zhì)性狀的影響. 植物營(yíng)養(yǎng)與肥料學(xué)報(bào), 2015, 21: 979–986.

Chen X G, Ding Y F, Tang Z H, Wei M, Shi X M, Zhang A J, Li H M. Suitable nitrogen rate for storage root yield and quality of sweet potato., 2015, 21: 979–986(in Chinese with English abstract).

[8] Duan W, Zhang H, Xie B, Wang B, Zhang L. Impacts of nitrogen fertilization rate on the root yield, starch yield and starch physicochemical properties of the sweet potato cultivar Jishu 25., 2019, 14: e0221351.

[9] 劉兆輝, 薄錄吉, 李彥, 孫明, 仲子文, 張英鵬, 井永蘋. 氮肥減量施用技術(shù)及其對(duì)作物產(chǎn)量和生態(tài)環(huán)境的影響綜述. 中國(guó)土壤與肥料, 2016, (4): 1–8.

Liu Z H, Bo L J, Li Y, Sun M, Zhong Z W, Zhang Y P, Jing Y P. Effect of nitrogen fertilizer reduction on crop yield and ecological environment: a review., 2016, (4): 1–8(in Chinese with English abstract).

[10] 王良平, 張菡, 樂(lè)正碧, 黎華, 王季春. 密度和施肥對(duì)甘薯品種‘萬(wàn)薯5號(hào)’淀粉含量的影響. 作物雜志, 2012, (1): 108–110.

Wang L P, Zhang H, Le Z B, Li H, Wang J C. The effect of planting density and Fertilization on the starch content of high-starch sweet potato Wanshu 5., 2012, (1): 108–110(in Chinese with English abstract).

[11] 黃華宏, 陸國(guó)權(quán), 鄭遺凡. 不同生育期甘薯塊根淀粉糊化特性的差異. 中國(guó)農(nóng)業(yè)科學(xué), 2005, 38: 462–467.

Huang H H, Lu G Q, Zheng Y F. Variation in root starch gelatinization characteristics during the growth and development of sweet potato., 2005, 38: 462–467(in Chinese with English abstract).

[12] 李臣, 薛冠煒, 黃靜艷, 王寧東, 陸國(guó)權(quán). 生育期對(duì)鮮食甘薯品種‘心香’營(yíng)養(yǎng)成分及產(chǎn)品加工特性的影響. 浙江農(nóng)業(yè)學(xué)報(bào), 2017, 29: 1957–1962.

Li C, Xue G W, Huang J Y, Wang N D, Lu G Q. Effects of different growth stages on nutritional components and processing characteristics of sweet potato cultivar Xinxiang., 2017, 29: 1957–1962(in Chinese with English abstract).

[13] 嚴(yán)美玲, 殷巖, 姜鴻明, 丁曉儀, 于經(jīng)川, 王江春. 氮肥用量對(duì)小麥籽粒粒重及淀粉含量的影響. 麥類作物學(xué)報(bào), 2008, 28: 1011–1015.

Yan M L, Yin Y, Jiang H M, Ding X Y, Yu J C, Wang J C. Effects of nitrogen amount on grains weight and amylose, amylopectin content of wheat., 2008, 28: 1011–1015(in Chinese with English abstract).

[14] 孫濤, 同拉嘎, 趙書宇, 王海微, 韓云飛, 張忠臣, 金正勛. 氮肥對(duì)水稻胚乳淀粉品質(zhì)、相關(guān)酶活性及基因表達(dá)量的影響. 中國(guó)水稻科學(xué), 2018, 32: 475–484.

Sun T, Tong L G, Zhao S Y, Wang H W, Han Y F, Zhang Z C, Jin Z X. Effects of nitrogen fertilizer application on starch quality, activities and gene expression levels of related enzymes in rice endosperm., 2018, 32: 475–484(in Chinese with English abstract).

[15] 李勇, 呂文河, 呂典秋, 宿飛飛, 李輝, 胡林雙, 楊煥春, 劉振宇, 王紹鵬, 劉尚武. 施氮水平對(duì)不同淀粉型馬鈴薯塊莖產(chǎn)量和淀粉品質(zhì)的影響. 中國(guó)農(nóng)業(yè)大學(xué)學(xué)報(bào), 2019, 24(3): 27–38.

Li Y, Lyu W H, Lyu D Q, Su F F, Li H, Hu L S, Yang H C, Liu Z Y, Wang S P, Liu S W. Effects of nitrogen fertilizer application rote on the tuber yield and starch quality of potato varieties with different starch contents., 2019, 24(3): 27–38(in Chinese with English abstract).

[16] 唐忠厚, 張愛(ài)君, 陳曉光, 靳容, 劉明, 李洪民, 丁艷鋒. 低鉀脅迫對(duì)甘薯塊根淀粉理化特性的影響及其基因型差異. 中國(guó)農(nóng)業(yè)科學(xué), 2017, 50: 513–525.

Tang Z H, Zhang A J, Chen X G, Jin R, Liu M, Li H M, Ding Y F. Starch physicochemical properties and their difference in three sweet potato genotypes under low potassium stress., 2017, 50: 513–525(in Chinese with English abstract).

[17] 陸國(guó)權(quán), 李秀玲, 丁守仁. 鹽酸水解DNS比色法快速測(cè)定甘薯淀粉含量的標(biāo)準(zhǔn)方法研究. 中國(guó)糧油學(xué)報(bào), 2002, (1): 25–28.

Lu G Q, Li X L, Ding S R. Quick analysis of starch content of sweet potato by HCL hydrolysis–DNS method., 2002, (1): 25–28 (in Chinese with English abstract).

[18] 包勁松. 應(yīng)用RVA測(cè)定米粉淀粉成糊溫度. 中國(guó)水稻科學(xué), 2007, 21: 543–546.

Bao J S. Accurate measurement of pasting temperature of rice flour by a Rapid Visco Analyzer., 2007, 21: 543–546(in Chinese with English abstract).

[19] Qiao D L, Tu W Y, Liao A P, Li N N, Zhang B J, Jiang F T, Zhong L, Zhao S M, Zhang L, Lin Q L. Multiscale structure and pasting digestion features of yam bean tuber starches., 2019, 213: 199–207.

[20] Bao J S, Shen S Q, Sun M, Corke H. Analysis of genotypic diversity in the starch physicochemical properties of nonwaxy rice: apparent amylose content, pasting viscosity and gel texture., 2006, 58: 259–267.

[21] Sandhu K S, Siroha A K. Relationships between physicochemical, thermal, rheological anddigestibility properties of starches from pearl millet cultivars., 2017, 83: 213–244.

[22] 曹健康. 果蔬采后生理生化實(shí)驗(yàn)指導(dǎo). 北京: 中國(guó)輕工業(yè)出版社, 2017. pp 81–84.

Cao J K. Guidance for Postharvest Physiological and Biochemical Experiments of Fruits and Vegetables. Beijing: China Light Industry Press, 2017. pp 81–84 (in Chinese).

[23] 周志林, 唐君, 曹清河, 趙冬蘭, 張安. 淀粉專用型甘薯品質(zhì)形成規(guī)律及其與主要農(nóng)藝性狀的相關(guān)性. 江蘇農(nóng)業(yè)學(xué)報(bào), 2020, 36: 277–283.

Zhou Z L, Tang J, Cao Q H, Zhao D L, Zhang A. Formation laws of quality characters in starch sweet potato cultivars and its correlation with main agronomic characters., 2020, 36: 277–283 (in Chinese with English abstract).

[24] 侯夫云, 陳桂玲, 董順旭, 解備濤, 秦楨, 李愛(ài)賢, 張立明, 王慶美. 不同品種甘薯淀粉組分、物化及粉條品質(zhì)的比較研究. 核農(nóng)學(xué)報(bào), 2022, 36: 392–401.

Hou F Y, Chen G L, Dong S X, Xie B T, Qin Z, Li A X, Zhang L M, Wang Q M. Comparative study on starch components, physicochemical properties and noodle quality of different sweet potato varieties., 2022, 36: 392–401 (in Chinese with English abstract).

[25] 柳強(qiáng)娟, 康建宏, 吳佳瑞, 孫建波, 馬雪瑩, 王星強(qiáng), 堅(jiān)天才. 施氮量對(duì)寧夏旱區(qū)馬鈴薯塊莖淀粉形成和產(chǎn)量的影響. 核農(nóng)學(xué)報(bào), 2021, 35: 1196–1208.

Liu Q J, Kang J H, Wu J R, Sun J B, Ma X Y, Wang X Q, Jian T C. Effects of nitrogen application amount on formation and yield of potato tuber starch in Ningxia arid region., 2021, 35: 1196–1208 (in Chinese with English abstract).

[26] 張友良, 汪兆輝, 馮紹元, 王鳳新. 覆膜滴灌條件下滴灌濕潤(rùn)比和施氮量對(duì)甘薯生長(zhǎng)的影響. 農(nóng)業(yè)機(jī)械學(xué)報(bào), 2021, 52(7): 261–270.

Zhang Y L, Wang Z H, Feng S Y, Wang F X. Effects of soil wetted percentages and nitrogen fertilizations on sweet potato growth under drip irrigation with film mulching., 2021, 52(7): 261–270 (in Chinese with English abstract).

[27] 項(xiàng)超, 沈升法, 吳列洪, 李兵, 羅志高. 甘薯塊根淀粉酶特性及糖化效應(yīng)研究. 中國(guó)糧油學(xué)報(bào), 2021, 36(5): 56–61.

Xiang C, Shen S F, Wu L H, Li B, Luo Z G. The characteristics of amylase and sweetening effect of sweet potato root., 2021, 36(5): 56–61 (in Chinese with English abstract).

[28] 朱紅, 鈕福祥, 徐飛, 孫健, 岳瑞雪, 張毅. 鉀肥對(duì)甘薯產(chǎn)量、品質(zhì)及淀粉RVA特性的影響. 江蘇農(nóng)業(yè)科學(xué), 2016, 44(5): 138–139, 195.

Zhu H, Niu F X, Xu F, Sun J, Yue R X, Zhang Y. Effects of potassium fertilizer on yield, quality and RVA characteristics of sweet potato., 2016, 44(5): 138–139, 195 (in Chinese with English abstract).

[29] 周治寶, 王曉玲, 余傳元, 雷建國(guó), 胡培松, 王智權(quán), 李馬忠, 朱昌蘭. 秈稻米飯食味與品質(zhì)性狀的相關(guān)性分析.中國(guó)糧油學(xué)報(bào), 2012, 27(1): 1–5.

Zhou Z B, Wang X L, Yu C Y, Lei J G, Hu P S, Wang Z Q, Li M Z, Zhu C L. Correlation analysis of eating quality with quality characters of indica rice., 2012, 27(1): 1–5 (in Chinese with English abstract).

[30] 胡雅杰, 薛建濤, 吳培, 李孌, 叢舒敏, 余恩唯, 倪嘉顥, 張洪程. 施氮量和直播密度對(duì)稻米食味品質(zhì)和淀粉結(jié)構(gòu)的影響. 中國(guó)糧油學(xué)報(bào), 2022, 37(2): 7–13.

Hu Y J, Xue J T, Wu P, Li L, Cong S M, Yu E W, Ni J H, Zhang H C. Effects of nitrogen application and sowing density on eating quality and starch structure of direct-seeding rice., 2022, 37(2): 7–13 (in Chinese with English abstract).

[31] 譚洪卓, 譚斌, 劉明, 田曉紅, 谷文英. 甘薯淀粉性質(zhì)與其粉絲品質(zhì)的關(guān)系. 農(nóng)業(yè)工程學(xué)報(bào), 2009, 25(4): 286–292.

Tan H Z, Tan B, Liu M, Tian X H, Gu W Y. Relationship between properties of sweet potato starch and qualities of sweet potato starch noodles., 2009, 25(4): 286–292 (in Chinese with English abstract).

[32] 余樹(shù)璽, 邢麗君, 木泰華, 張苗, 孫紅男, 陳井旺. 4種不同甘薯淀粉成分、物化特性及其粉條品質(zhì)的相關(guān)性研究. 核農(nóng)學(xué)報(bào), 2015, 29: 734–742.

Yu S X, Xing L J, Mu T H, Zhang M, Sun H N, Chen J W. The study of correlation between the physicochemical properties of starch from different sweet potato varieties and the quality of its starch noodle., 2015, 29: 734–742 (in Chinese with English abstract).

[33] 江帆, 杜春微, 任妍婧, 梁雞保, 杜雙奎. 不同藜麥品種淀粉的理化性質(zhì)與消化特性. 中國(guó)糧油學(xué)報(bào), 2021, 36(7): 77–83.

Jiang F, Du C W, Ren Y J, Liang J B, Du S K. Physicochemical properties and digestibility of starches of different quinoa varieties., 2021, 36(7): 77–83 (in Chinese with English abstract).

[34] Zheng M J, Ye A, Singh H, Zhang Y. The in vitro digestion of differently structured starch gels with different amylose contents., 2021, 116: 106647.

[35] 唐敏敏, 洪雁, 顧正彪, 劉月. 黃原膠對(duì)綠豆淀粉糊化和流變特性的影響. 食品科學(xué), 2013, 34(21): 42–46.

Tang M M, Hong Y, Gu Z B, Liu Y. Effects of xanthan on pasting and rheological properties of mung bean starch., 2013, 34(21): 42–46 (in Chinese with English abstract).

[36] Khatkar B S, Bell A E, Schofield J D. The dynamic rheological properties of glutens and gluten subfractions from wheats of good and poor bread making quality., 1995, 22: 29–44.

[37] Ye F, Li J, Zhao G. Physicochemical properties of different-sized fractions of sweet potato starch and their contributions to the quality of sweet potato starch., 2020, 108: 106023.

[38] 譚洪卓, 谷文英, 劉敦華, 陸建安. 甘薯淀粉糊的流變特性. 食品科學(xué), 2007, 28(1): 58–63.

Tan H Z, Gu W Y, Liu D H, Lu J A. Rheological properties of sweet potato starch paste., 2007, 28(1): 58–63 (in Chinese with English abstract).

Effects of nitrogen fertilizer application rate on starch contents and properties during storage root expansion in sweetpotato

WU Shi-Yu1,2, CHEN Kuang-Ji1,3, LYU Zun-Fu1,2, XU Xi-Ming1,2, PANG Lin-Jiang2,4, and LU Guo-Quan1,2,*

1College of Advanced Agricultural Sciences, Zhejiang A&F University / Key Laboratory for Quality Improvement of Agricultural Products of Zhejiang Province, Hangzhou 311300, Zhejiang, China;2Institute of Root & Tuber Crops, Zhejiang A&F University, Hangzhou 311300, Zhejiang, China;3Yizheng Agricultural Technology Comprehensive Service Center, Yangzhou 211400, Jiangsu, China;4College of Food and Health, Zhejiang A&F University, Hangzhou 311300, Zhejiang, China

In order to explore the effect of nitrogen fertilizer application rate on starch contents and properties during storage root expansion of sweetpotato ((L.) Lam.), two sweetpotato cultivars (‘Xinxiang’ and ‘Shangshu 19’) were taken as the experimental materials, and three nitrogen fertilizer application rates (0 kg hm–2(CK), 57.5 kg hm–2(N1), and 115 kg hm–2(N2)) were designed and conducted on the day of planting. To investigate the changes of starch content, starch gelatinization properties, starch dynamic rheological properties, gel texture properties, and amylase activity in sweetpotato storage roots during storage root expansion, the storage root samples were collected at the 60th, 80th, 100th, 120th, and 140th days after planting. Results were as follows: (1) Nitrogen fertilizer application could significantly increase the starch content of two cultivars during storage root expansion, but significantly reduce the hot paste viscosity (HPV), cold paste viscosity (CPV), and setback viscosity (SBV) of starch gelatinization properties of ‘Xinxiang’ at the initial stage of storage root expansion (IES), and significantly decrease the HPV, CPV, and SBV of ‘Shangshu 19’, while remarkably increase the HPV, CPV, and SBV of ‘Xinxiang’ at the late-expanding stage of storage root expansion (LES). (2) The hardness and chewiness of starch gel under three nitrogen fertilizer application treatments gradually decreased during storage root expansion. Among them, N2 treatment could significantly improve the hardness of gel of sweetpotatoes at LES. (3) The starch gel of two cultivars exhibit elastic properties. N1 and N2 treatments could increase the storage modulus and loss modulus of ‘Xinxiang’ whereas reduce the storage modulus and loss modulus of ‘Shangshu 19’. (4) Nitrogen fertilizer application rates reduced the amylase activity at IES, but increased the amylase activity at LES of the two cultivars. Therefore, nitrogen fertilizer application rate obviously affected the starch contents and properties of sweetpotatoes during storage root expansion. Moreover, ‘Shangshu 19’ with 115 kg hm–2of nitrogen fertilizer application rate harvesting on 120 days after planting, which was conducive to the processing properties of sweetpotato starch. In conclusion, reasonable nitrogen application and timely harvest were beneficial to the accumulation and quality improvement of sweetpotato starch.

sweetpotato; nitrogen fertilizer; storage root expansion stage; starch; physicochemical properties

10.3724/SP.J.1006.2023.24087

本研究由財(cái)政部和農(nóng)業(yè)農(nóng)村部國(guó)家現(xiàn)代農(nóng)業(yè)產(chǎn)業(yè)技術(shù)體系建設(shè)專項(xiàng)(CARS-10), 浙江省重點(diǎn)研發(fā)計(jì)劃項(xiàng)目(2021C02057, 2022C02041- 2), 浙江省三農(nóng)九方科技協(xié)作項(xiàng)目(2022SNJF008)和浙江省教育廳科研資助項(xiàng)目(Y202147184)資助。

This study was supported by the China Agriculture Research System of MOF and MARA (CARS-10), the Zhejiang Key Research and Development Program (2021C02057, 2022C02041-2), the Zhejiang Sannong Jiufang Science and Technology Cooperation Project (2022SNJF008), and the General Research Program for the Education Department of Zhejiang Province (Y202147184).

陸國(guó)權(quán), E-mail: lugq10@zju.edu.cn

E-mail: wsyu@stu.zafu.edu.cn

2022-04-07;

2022-09-05;

2022-09-15.

URL: https://kns.cnki.net/kcms/detail/11.1809.S.20220914.1708.002.html

This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).