Mathematical modelling of the diffusion of ascorbic acid during water blanching of surface frozen potato strips

Partial freezing is a promising technique in producing good quality french fries, especially for potatoes stored for an extended period and containing large amounts of reducing sugars. The cell damage of the potato strip caused by surface freezing facilitates surface leaching of reducing sugars and other soluble solids like ascorbic acid, preventing undesirable dark colour in the finish-fried products. A theoretical study to describe the diffusion of ascorbic acid during the water blanching at 50°C of surface frozen potato strips (10 x 10 x 80 mm) is developed. Ascorbic acid profiles as a function of blanching time, position in the potato strip and thickness of the frozen layer are shown as well as average retention as a function of blanching time, frozen layer thickness, apparent diffusion coefficient and mass transfer coefficient of ascorbic acid. Significant changes in the ascorbic acid concentration during blanching are produced in the frozen layer. Ascorbic acid average retention is mainly influenced by frozen layer thickness and temperature, and the mass transfer coefficient is less important.     

Automated determination of total sugars in sugar crops grown for energy

A fast, accurate method for determining total sugars in sugar crops was developed. Sugars were quantitatively removed from the tissue by homogenisation and hot water extraction. Lead acetate was used to clarify the extract by precipitating any interfering non-sugar reducing substances. Lead was then removed by precipitation with sodium oxalate. The extract was hydrolysed to convert sucrose into glucose and fructose. After neutralising, total sugars were determined as total reducing sugars by automated colorimetry using a Technicon Auto-Analyzer. Data presented show optimum conditions for extraction, clarification and acid hydrolysis of sucrose to reducing sugars. The method has a precision of 2.1% coefficient of variation for 10 consecutive analyses of a sweet sorghum sample with a mean total sugar concentration of 14.2±0.3%.     

浓缩苹果汁加工中酶作用及贮藏稳定性研究

以红富士苹果浓缩汁为材料,采用单因素试验,研究果胶酶和α- 淀粉酶对还原糖、总酸、可溶性固形物等几个指标的影响,同时找出适合浓缩苹果汁澄清的果胶酶和α- 淀粉酶的酶用量、温度和时间。实验结果表明,在酶用量0.1%、温度50℃、时间1.5h 的条件下,浓缩苹果汁的澄清效果较明显。将加入果胶酶和α- 淀粉酶的浓缩苹果汁置于4℃和26℃条件下贮藏,测定其在贮藏过程中还原糖含量、总酸含量、pH 值和透光率等指标的变化。结果表明,在4 ℃贮藏条件下,随着贮藏时间的延长,还原糖含量、总酸含量、pH 值、透光率变化幅度较小,果汁营养成分保持较好,适宜贮藏。     

MODELLING DRY MATTER LOSSES FROM CARROTS DURING BLANCHING

The mechanism of component losses from carrots during blanching was investigated by determination of reducing sugars, sucrose, total soluble solids and total solids in raw and variously blanched samples of Nantes carrots. the samples were 26 mm diameter, 26 or 60 mm long; blanching temperatures ranged 65–100°C and blanching times ranged 300–3600 s. Experiments were conducted using large amounts of well agitated water. Appropriate solutions of the unsteady state diffusion equation for finite cylinder geometry were used. the apparent diffusivities of each component were determined separately at different temperatures and resulting values correlated linearly or exponentially with temperature. the order-of-magnitudes of the apparent diffusivities were found to be 10^?10-10^?11 m²s^?1 and in good agreement with literature values.     

响应曲面优化甘蔗糖蜜酸水解工艺研究

采用响应曲面法对影响甘蔗糖蜜水解总还原糖得率的3个主要影响因素即硫酸浓度、水解温度、水解时间进行优化。利用Design Expert软件分析表明：在甘蔗糖蜜糖度65、硫酸浓度4%、水解温度94℃、水解时间66 min的工艺条件下,100 g甘蔗原糖蜜水解后获得总还原糖54.98 g,实测结果与响应面拟合所得方程的预测值相符合。     

Effect of salting and roasting on the carbohydrates and proteins of Iranian pistachio kernels

The free sugars which make up 2.7% of Iranian pistachio cv Badami were identified as fructose, glucose, sucrose, maltose, isomaltose, cellobiose, raffinose and stachyose. Both protein and free amino acids contained the same seventeen amino acids but lacked tryptophan, asparagine and glutamine. After salting and roasting, total available carbohydrates, total starches and dextrins, and total free sugars all decreased compared to controls, as did a number of individual sugars, especially the reducing sugars. While free amino acids had severely decreased, total protein amino acids and individual protein amino acid were not affected at all. The decreases in reducing sugars and in free amino acids may be due in part to their taking part in Maillard reactions.     

扛板归多糖含量测定方法的建立

建立扛板归多糖的含量测定方法,效应面分析法研究扛板归多糖含量测定的最佳条件。以葡萄糖为标准品,采用苯酚-硫酸法和3,5-二硝基水杨酸法,分别测定扛板归水提液中总糖和还原糖的含量,从而计算多糖含量;在单因素试验的基础上,运用三因素五水平的星点设计-效应面分析法优选多糖测定的最佳条件。最佳测定条件如下,总糖:苯酚用量1.7 mL,硫酸用量8.7 mL,显色时间11 min;还原糖:显色剂用量2.7 mL,显色时间10 min,显色温度81 ℃。在最佳测定条件下,总糖和还原糖的样品加标回收率分别为102.26%(RSD=4.03%,n=9)和102.89%(RSD=2.66%,n=9)。扛板归多糖含量为46.72 mg/g。本方法灵敏、稳定、重复性好,可用于扛板归多糖含量的测定。     

STUDIES ON THE EFFECT OF GERMINATION TIME AND TEMPERATURE ON MALTING OF RICE

The effect of germination conditions on rice malt quality was studied by germinating rice for different periods of time up to 7 days over a range of temperatures (22° to 32°C). Germination time and temperature had a significant effect on rice malt diastatic power, cold and hot water extracts, total reducing sugars, and free alpha amino nitrogen. In general, diastatic power, cold water extract, hot water extract, total reducing sugars and free alpha amino nitrogen, all increased with germination time and temperature. Germination temperatures of 28°C and 30°C were good for the development of diastatic power, cold water extract, hot water extract, total reducing sugars and free alpha amino nitrogen. However germinating at 30°C gave maximum result. The mashing trials with rice malted for 6 days showed a slow and incomplete saccharification, slow filtration rate, and high total available extract in spent grains.     

不同品种甘蔗制成的红糖品质差异研究

选择用于红糖加工代表性较强的16个甘蔗品种为原材料,采用传统工艺法熬制红糖,对红糖样品的营养指标、品质指标、多种矿物质元素、总游离氨基酸和总多酚含量进行比较分析。结果表明:参试品种选三、柳城05-136、川糖61-408、台糖134和CO 419制成的红糖品质和营养指标均较好;四川芦蔗和桂林竹蔗制成的红糖因为蔗糖含量过低而还原糖含量过高,不易成型且易吸潮而不适合制作红糖,但二者的总多酚含量最高,总游离氨基酸含量也能达到1317.84 mg/100 g~1346.10 mg/100 g,可以考虑作为生产液体红糖的原料;云蔗05-51制成的红糖蔗糖分最高,ROC 25制成的红糖氯化物含量最高,这二者更适合生产需要结晶提纯的白砂糖;其余品种制成的红糖品质和营养指标均较为适中,可根据需要进行合理开发。     

Contents and digestibility of carbohydrates of chickpea and black gram as affected by domestic processing and cooking

Starch digestibility (in vitro) and level of total soluble sugars, reducing sugars, non-reducing sugars and starch in cultivars of chickpea (Cicer arietinum), as well as black gram (Vigna mungo), varied significantly. The effects of different domestic processing and cooking methods on the contents of starch, sugars and starch digestibility (in vitro) of eight varieties of chickpea and four of black gram were investigated. Cooking, autoclaving and germination decreased the starch content and increased the level of total soluble sugars, reducing sugars, non-reducing sugars and starch digestibility of both the legumes. Soaking reduced the sugars considerably but starch only marginally. Autoclaving increased starch digestibility more than 4-fold and 5-fold in chickpea and black gram, respectively. Cooking and sprouting also improved starch digestibility appreciably.     

发芽糙米营养成分及淀粉糊化特性研究

以3个粳稻和2个糯稻为原料,制备发芽糙米,分析了糙米发芽前后游离氨基酸、蛋白质、水溶性糖类、脂肪酸值以及Mixolab淀粉糊化特性的变化。结果表明,与糙米相比,发芽糙米游离氨基酸总量、水溶性总糖、还原糖及果胶酸含量显著增加。Mixolab混合仪测定的发芽糙米米粉团蛋白质结构严重弱化,淀粉糊化能力显著降低。油酸含量和脂肪酸值均增加。发芽糯糙米水溶性总糖、还原糖及果胶酸含量显著高于发芽粳糙米,破损淀粉含量显著低于发芽粳糙米。     

Cassava Starch or Amylose Effects on Characteristics of Cassava (Manihot esculenta Crantz) Extrudate

Blends of cassava flour with cassava starch or amylose were processed on a Wenger X-5 laboratory extruder. Cassava starch added to cassava flour increased total carbohydrate in feed, reducing yellow color, water absorption and extrudate bulk density but increased expansion, product moisture, water solubility and total reducing sugars. Amylose addition increased extrudate surface regularity with reduced water solubility, total reducing sugars, and bulk density. Expansion was highest in mixtures containing 60% amylose. Textural properties of extrudate increased on addition of amylose or cassava starch. Differences in microstructures existed between cassava flour and cassava starch extrudate.     

Simultaneous Solid Phase Fermentation and Saccharification of Cassava Fibrous Residue for Production of Ethanol

A total of 16.5% reducing sugars in the saccharified pulp of cassava fibrous residue are achieved with the use of 30% slurry. The yield of ethanol was highest and the amount of residual reducing sugars was lowest with the use of 2.5% acid. The increase in dose of glucoamylase leads to improved yields of ethanol without any lowering in the residual reducing sugars. The ethanol yield and productivity were better and the residual reducing sugars were lower in solid phase fermentation as compared to the fermentation of liquid hydrolysate obtained by hydraulic pressing of the saccharified pulp. The slightly lower yield of ethanol in large batch static fermentation probably due to poor mass transfer and limited contact of yeast cells as well as enzyme with their substrates could be effectively overcome by employing appropriate strategies.     

Heat and Mass Transfer During the Warm Water Blanching of Potatoes

A model of heat and mass transfer with simultaneous chemical reaction is proposed for analyzing the influence of operating variables on the reducing sugar content at the surface of blanched potatoes. This content is partially responsible for the color of the finished product. The involved parameters (potato thermal conductivity, heat transfer coefficient of the system and kinetic constants for overall reaction of reducing sugar generation) were evaluated in separate experiments. The apparent diffusion coefficient of reducing sugars in potatoes was the only parameter obtained from blanching experiments. Temperature and concentration profiles and effect of blanching temperature on surface reducing sugar content are analyzed using the developed model. The possible underestimation of the diffusion coefficient when simultaneous starch hydrolysis is not taken into account is also considered.     

COMPOSITIONAL ANALYSIS OF FOUR RED RASPBERRY CULTIVARS GROWN IN MAINE

The compositional characteristics (total soluble solids, pH, titratable acidity, moisture, pectin, reducing sugars, nonreducing sugars and total sugars) of four raspberry cultivars (‘Boyne’, ‘Festival’, ‘Killarney’ and ‘Prestige’) grown in Maine were evaluated during three consecutive years. Significant differences were found among these cultivars. In different growing seasons there were also significant effects on these characteristics in the same cultivar.     

CHANGES IN THE FREE SUGAR CONTENT OF BARLEY KERNELS DURING MATURATION

The free sugars extracted from kernels of a two-row barley variety, Betzes, were separated and determined quantitatively as negatively-charged borate derivatives by anion-exchange chromatography on substituted polystyrene resin. Sugars were determined at 2 or 3 day intervals immediately following anthesis, until kernels achieved harvest ripeness. Initially, the free sugars accounted for 6.5% of kernel dry matter; reducing sugars comprised 80% of the total free sugars, primarily as fructose (3% of the kernel dry matter) and glucose (2% of kernel dry weight), with lesser amounts of galactose, mannose, and maltose. Sucrose was the principal non-reducing sugar (1.8% of the kernel dry weight), but traces of raffinose were also detected. As kernel dry matter increased, the relative amount of free sugars decreased rapidly and comprised 2% of the kernel dry matter in mature kernels. At harvest ripeness, non-reducing sugars comprised 90% of the total free sugars. Sucrose decreased slightly from 1.8 to 1.2% of total kernel dry matter, but actually increased from 90 μg in immature kernels to 500 μg in mature kernels; raffinose increased relative to kernel dry matter from trace amounts 20 days after anthesis to 0.7% of kernel dry matter (i.e., 250 μg/kernel) 36 days after anthesis, and declined to 0.4% in mature kernels. Non-reducing, soluble fructosans were present at all stages of kernel maturation, but were not determined quantitatively.     

Physicochemical and microbial quality evaluation of foam‐mat‐dried pineapple powder

Present experiments were carried to study the physicochemical and microbial quality of foam‐mat‐dried pineapple powder. Pineapple pulp was foamed using two foaming agents, tricalcium phosphate (TCP) (0%, 0.25%, 0.50%, 0.75%, and 1.0%) and egg white (EW) (0%, 0.50%, 1.0%, 1.50%, and 2.0%). Carboxy methyl cellulose (0.25%) was used as foam stabiliser, and drying was carried out at 65, 75, and 85 °C in tray drier followed by pulverising the dried foam mats in to fine powder. Powdered samples were analysed for various physicochemical quality parameters viz. total sugars, reducing sugars, ascorbic acid, total acid, pH, iron, phosphorus and calcium content, and bacterial and fungal load. Statistical analysis using LSD revealed that sample dried using 1% TCP at 65 °C was the best with 4.60% total sugars, 2.71% reducing sugars, 4.05 mg per 100 g ascorbic acid, 0.35% total acid, 0.29 mg per 100 g Iron, 2.24 mg per 100 g phosphorous, and 6.58 g per 100 g calcium and zero bacterial and fungal growth.     

多组分糖液中温度对碳酸钙形貌及其吸附能力的影响

本文采用聚焦光束反射测量仪（FBRM）、扫描电子显微镜（SEM）等手段在线监测不同饱充温度下生成的碳酸钙颗粒形貌及粒径变化,以还原糖含量、色值及简纯度等为指标,研究了饱充温度对碳酸钙形貌及其吸附能力的影响。结果表明：饱充温度为60和70 ℃时,碳酸钙颗粒主要呈细长棒状,FBRM测得的碳酸钙粒径较小,清净汁色值分别为281和289 IU,简纯度分别为93%和90%,过滤速度快,还原糖破坏少;而在80和90 ℃的较高饱充温度下,碳酸钙颗粒主要呈球状颗粒,结合得较紧密,FBRM测得的粒径较大,清净汁色值较高,分别为303和385 IU,简纯度较低,分别为87%和73%,过滤速度慢,还原糖破坏较多。因此温度在一定范围内会影响烟道气饱充生成的碳酸钙形貌和粒径及还原糖含量等,饱充温度越低,生成的碳酸钙颗粒对杂质的吸附效果越好,对糖液中还原糖的破坏也越少,有利于糖液清净。     

EFFECT OF SOAKING AND GERMINATION ON NUTRIENT AND ANTINUTRIENT CONTENTS OF FENUGREEK (TRIGONELLA FOENUM GRAECUM L.)

Fenugreek seeds (raw, soaked and germinated) were analyzed for their chemical composition. Raw fenugreek seeds contained higher amount of dietary fiber 46.50% followed by 42.12% in soaked seeds and 32.50% in germinated seeds. Soaking reduced the level of total soluble sugars, reducing sugars, nonreducing sugars, dietary fiber and improved the protein and starch digestibility and availability of minerals. Germinated fenugreek seeds had significantly higher contents of total protein (29%) and total lysine (6.48 g/100 g protein) compared to unprocessed seeds. Germination decreased dietary fiber and starch thereby raising the level of sugars. In vitro starch and protein digestibility and availability of Ca, Fe and Zn were also increased appreciably due to reduction in antinutrient contents (phytic acid and polyphenols) after 48 h germination.     

IMPROVED EXTRACTION AND ASSAY OF β-AMYLASE BROM BARLEY AND MALT

β-Amylase was extracted from barley or malt using four physical techniques to break up grists which had been prepared using a Moulinex coffee grinder. Grinding with a Polytron homogeniser apparently completely disrupted all cells, as determined by transmission electron microscopy, and increased the efficiency of extraction of β-amylase from barley by more than 30%. The other treatments tested were without value . The β-amylase activity in extracts of barley or malt was assayed by measuring the production of reducing sugars from reduced soluble starch, using a PAHBAH reagent. α-Amylase, which interferes with the quantitation of β-amylase in extracts of malt, was not totally inactivated by the chelating buffer used for enzyme extraction or by several other chelating agents. α-Amylase activity was quantified specifically using Phadebas. Using purified α-amylase a calibration was developed which related activity, as determined using Phadebas, to reducing power units. Thus the α-amylase activity present in an extract containing β-amylase could be determined using Phadebas and the reducing power equivalent activity subtracted from the total “apparent” activity to give the actual β-amylase activity. α-Glucosidase and limit dextrinase activities are believed to be too low to have a significant effect on the apparent β-amylase . The soluble and bound β-amylase activities were measured in samples taken from micromalting barley (Alexis). Dry weight losses increased to over 10% after 8 days germination. Antibiotics, applied during steeping, were used to control microbes in one experiment. However, their use checked germination and reduced malting losses to 8.4% in 8 days germination. The soluble enzyme present in extracts from steeped barley and early stages of germination was activated (20–40%) by additions of the reducing agent DTT .