小麦粉储存湿度对面粉品质及其制作馒头品质的影响

研究通用中筋粉在常温(25℃),不同湿度(50%、65%、80%)条件下储存过程中面粉中水分含量、粗蛋白质含量、湿面筋含量、脂肪酸值等指标及其制作面团的酸度和馒头的感官品质的变化。实验结果表明,在湿度80%条件下,随着储存时间的延长面粉水分含量变化显著(p<0.05)。同一储藏时间,湿度越高,面筋含量越低。不同湿度(50%、65%、80%)条件下,面粉中的脂肪酸值都随储存时间的增加而增加(p<0.05)。不同湿度(50%、65%、80%)储存过程的面粉制作的发酵面团的酸度都呈现先降低后增加的趋势,制作馒头的感官评分呈现下降的趋势(p<0.05)。面粉在不同湿度(50%、65%、80%)储存过程中,储存30 d的面粉,醒发后面团酸度都显著下降(p<0.05);继续延长储存期,在湿度50%下的面粉制作的面团酸度有回升,但不超过原始的面团酸度,随储存湿度提高面团酸度增加明显;感官评分表明,储存环境湿度越高,面粉制作的馒头品质下降越快,湿度80%储存60 d后的面粉制成的馒头口感差。湿度50%存放120 d仍可用于加工馒头。结论:面粉储存过程中,湿度越大,面粉品质下降越快,进而影响到所制作的馒头品质。     

谷物基质对东北黏豆包质构及化学性质的影响

采用传统自然发酵方法以大黄米面为主要原料制备的黏豆包发酵面团P (P_1, P_2, P_3和P_4)和以江米面为主要原料制备的黏豆包发酵面团G (G_1和G_2),通过全质构分析法、AOAC标准方法和高效液相色谱法分别测定传统发酵黏豆包面团的质构、酸度和可溶性糖含量,研究谷物基质对黏豆包面团质构特性及化学性质的影响。结果表明:面团P的硬度、胶黏性和咀嚼性都高于面团G (p0.05);面团P的pH低于面团G的pH (p0.05), P的TTA值高于G的TTA值(p0.05);此外,仅面团P3中葡萄糖含量与其他5种面团有差异,面团P与面团G的麦芽糖含量无差异。因此,不同谷物基质对黏豆包面团的部分质构特性和酸度有一定的影响,可能对面团的还原糖含量有影响。     

酵母菌发酵对小麦麸皮成分的影响研究

研究用酵母茵发酵小麦麸皮来降低植酸,增加可溶性阿拉伯木聚糖(SAX)和总酚含量以改善小麦麸皮营养价值。通过测定发酵pH和总滴定酸(TTA)及小麦麸皮成分(淀粉、蛋白质、膳食纤维、SAX、植酸、总酚含量)的变化,以研究发酵温度(25、30、35℃)和时间(12、24、36、48 h)对小麦麸皮的影响。结果表明,小麦麸皮经发酵后,pH略有下降,TTA上升;蛋白质显著增加;淀粉和膳食纤维下降;SAX和总酚含量均呈现先上升后下降的趋势,最大分别增加了212%和49.4%;植酸显著降低,在35℃、48 h发酵后最大下降了43.3%。经酵母菌发酵后,发酵酸度和小麦麸皮成分有显著变化。     

面糊发酵过程理化指标变化规律研究

以发酵过程中面糊为研究对象,研究不同发酵条件(面水比、酵母添加量、发酵温度)制作面糊在发酵过程中理化指标(pH、总酸度、α–淀粉酶活力、还原糖含量)变化规律。实验结果表明,面水比高的面糊其pH降速快,总酸度增速快,还原糖含量随发酵时间增加而降低,α–淀粉酶活力均呈现先增加、后降低。面糊酵母添加量为0.05%时,pH下降最快,总酸度含量最高,α–淀粉酶活力均呈先增加、后降低;且面糊酵母添加量高,还原糖含量低。面糊发酵温度高,其pH降速快,总酸度升高快,还原糖含量低;发酵温度对α–淀粉酶活力具有明显影响。     

预处理对欧李酒品质及抗氧化的影响

以欧李为原料,分别对欧李进行水浴和超声波预处理,采用分光光度法、pH值示差法、福林酚法分别测定不同预处理对欧李酒色调、色度、花色苷含量、多酚含量的影响,采用DPPH法和ABTS法研究抗氧化活性的变化,并探讨对应的欧李酒发酵过程中多酚含量和抗氧化活性的变化规律。结果表明,不同处理方式下的欧李酒在发酵过程中,色度、色调均呈下降趋势,发酵第12天时水浴组和超声波组与对照组相比无显著性差异(P>0.05);超声波组和水浴组花色苷含量显著高于对照组(P<0.05);多酚含量呈先升高后降低的趋势,发酵第12天时超声波组显著高于对照组(P<0.05);DPPH自由基、ABTS+自由基清除能力均在88%以上,具有较强的抗氧化性。相关性分析表明,欧李酒中的多酚含量与DPPH自由基、ABTS+自由基清除能力具有显著相关性(P<0.01)。     

发酵条件对湿法腌制黄瓜发酵性能的影响

以黄瓜为主要原料,以香辛料、蔗糖等为辅料,将处理好的黄瓜进行常温湿法腌制。通过测定腌黄瓜汁液中的乳酸菌数、残糖(%)、酸度(g/L)等,研究蔗糖添加量(%)、香辛料添加量(%)、食盐水浓度(%)以及腌制天数(天)等发酵因素对湿法腌制黄瓜发酵性能的影响。研究结果表明:随着蔗糖添加量升高,可溶性固形物含量随之增大,而酸度先上升后下降,差异显著(P0.05);随着香辛料添加量升高,酸度先上升后下降,且差异显著(P0.05);随着食盐添加量的升高,可溶性固形物含量随之增大,酸度随之增大;随着腌制天数延长,酸度出现上升趋势;酸度与蔗糖添加量、香辛料添加量、食盐水浓度及发酵天数的相关系数分别为-0.769,-0.012,0.844,-0.952,且有统计学意义;乳酸菌数量与蔗糖添加量、香辛料添加量、食盐水浓度及发酵天数的相关系数分别为-0.627,-0.750,-0.871,-0.210;可溶性固形物与蔗糖添加量、香辛料添加量、食盐水浓度及发酵天数的相关系数分别为-0.984,0,0.966,0.230。     

接种植物乳杆菌和蔗糖添加量对发酵香肠品质特性的影响

研究接种植物乳杆菌6003和蔗糖添加量（0.4%和1.5%）对发酵香肠品质的影响。结果表明：接种植物乳杆菌6003,可加速发酵过程中pH值的降低;发酵香肠的硫代巴比妥酸反应物（thiobarbituric acid reactive substances,TBARs）值和总挥发性盐基氮（total volatile basic nitrogen,TVB-N）含量显著降低（P＜0.05）;发酵香肠菌落总数和乳酸菌数在发酵过程中迅速增加（P＜0.05）,在贮藏期间显著减少后趋于平稳,且菌落总数和乳酸菌数显著高于自然发酵香肠（P＜0.05）;此外,接种后的发酵香肠具有更高的硬度及总体可接受度评分,颜色无显著变化。发酵后,随着贮藏时间的延长,各组发酵香肠的pH值和可滴定酸度无显著变化,黏聚性、亮度值、红度值和水分活度显著降低,黄度值、TBARs值、TVB-N含量、硬度、咀嚼度和胶着度显著升高;不同添加量蔗糖对发酵香肠相关参数的影响较小。因此,选择蔗糖添加量0.4%和植物乳杆菌6003接种量7（lg（CFU/g））的方法生产发酵香肠较为适宜。     

酸奶发酵和冷藏过程中品质评价及主要风味成分变化分析

为探明酸奶发酵和冷藏过程中的品质特性及主要风味成分变化情况,测定了酸奶在发酵和冷藏过程中的pH值、酸度、持水力、黏度等理化指标以及乳酸菌活菌数和氨基酸、脂肪酸等风味成分含量。结果表明,酸奶持水力和黏度变化趋势相同,在发酵和冷藏前期逐渐增加,后期平缓下降;发酵阶段酸度显著升高,而p H值显著下降,且均有显著性差异(P <0. 05),冷藏阶段均变化不显著;乳酸菌数量、氨基酸总量、必需氨基酸和非必需氨基酸以及鲜味氨基酸含量在发酵和冷藏阶段呈现逐渐增加—迅速降低—缓慢上升的趋势;脂肪酸含量在发酵和冷藏期间持续上升,其中多不饱和脂肪酸在发酵和冷藏阶段逐渐降低,而短链脂肪酸、中链脂肪酸及长链脂肪酸逐渐增加,均无显著性变化。该研究为酸奶及发酵乳制品的研发和品质评价提供一定的理论基础。     

抗氧化剂处理对微冻贮藏泥鳅品质及脂肪氧化的影响

研究丁香提取物、油菜粉提取物、植酸、VE及2,6-二叔丁基对甲苯酚(BHT)处理对微冻(-2.5℃)贮藏泥鳅品质及脂肪氧化的影响。结果显示,不同处理组泥鳅的感官综合得分逐渐降低;pH值先下降后上升;汁液流失率呈增加趋势;剪切力不断降低(P0.05);挥发性盐基氮(TVB-N)值呈增加趋势,且所有处理组在24d时均小于最大限量(20mg/100g),处于可接受范围;硫代巴比妥酸值(TBARS)、过氧化值(POV)均呈上升趋势(P0.05);饱和脂肪酸(SFA)、单不饱和脂肪酸(MUFA)含量整体升高,多不饱和脂肪酸(PUFA)含量相对下降。以上所有处理组的变化趋势均优于对照组。综合上述分析,对照组在微冻条件下的货架期为8～12d,而添加抗氧化剂组货架期均达到20～24d,其中植酸、BHT以及VE抗氧化能力更强,能够更有效地抑制不饱和脂肪酸氧化,维持样品的食用品质和加工性能。     

益生菌对发酵乳理化性质影响的研究

通过比较不同菌种发酵乳和酸乳在4℃下贮藏21d的pH、酸度、活菌数与持水力的差异,并对后熟24h的发酵乳和酸乳进行质构特性分析。结果显示,益生菌发酵乳和乳酸菌酸乳的pH、活菌数与酸乳持水力均随时间的延长而降低,酸度呈上升趋势,益生菌发酵乳酸度值比乳酸菌酸乳更高。添加干酪乳杆菌与植物乳杆菌的益生菌发酵乳在硬度、稠度、凝聚性与黏度上与乳酸菌酸乳相比,均有所增加,其中添加植物乳杆菌的益生菌酸乳在硬度与稠度上较乳酸菌酸乳相比有显著增加(p<0.05),为发酵乳制品提供开发导向并为实际生产提供理论依据。     

Fermentation and enzyme treatment of tannin sorghum gruels: effects on phenolic compounds,phytate and in vitro accessible iron

The presence of polyphenols and phytate in cereal products has been shown to interfere with the bioavailability of minerals such as iron. In the present study, we added enzymes (wheat phytase and mushroom polyphenol oxidase) during fermentation of tannin sorghum gruels prepared from flour with or without addition of 5% flour of germinated tannin-free sorghum grains (power flour), and investigated the effects on phenolic compounds, phytate and in vitro accessible iron. Assayable phenolic compounds were significantly reduced by fermentation, with high reductions observed in gruels with added enzymes. Fermentation of the gruels with addition of enzymes reduced (on average) total phenols by 57%, catechols by 59%, galloyls by 70% and resorcinols by 73%. The phytate content was significantly reduced by fermentation (39%), with an even greater effect after addition of power flour (72%). The largest reduction of phytate (88%) was, however, obtained after addition of phytase. The in vitro accessible iron was 1.0% in the sorghum flour and it increased after fermentation with power flour and/or with enzymes. The highest in vitro accessibility of iron (3.1%) was obtained when sorghum was fermented with addition of power flour and incubated with phytase and polyphenol oxidase after the fermentation process.     

Phytic acid and extractable phosphorus of pearl millet flour as affected by natural lactic acid fermentation

Lactic acid fermentation of pearl millet flour decreased its phytic acid content and increased extractable phosphorus. Fermentation at 40 and 50°C for 72 h or longer eliminated phytic acid almost completely; extractable phosphorus was more than doubled. Lower temperatures (20 and 30°C) were less effective. The changes in concentration of phytic acid and extractable phosphorus may be attributed partly to phytase activity inherent in pearl millet flour.     

Changes in mineral absorption inhibitors consequent to fermentation of Ethiopian injera: implications for predicted iron bioavailability and bioaccessibility

Possible changes in mineral bioavailability during processing of different types of injera sampled in Ethiopian households were assessed using different methods: phytic acid/mineral molar ratio, absorption prediction algorithm and in vitro availability measurements. Most foods analysed were rich in iron, but most of the iron likely resulted from soil contamination. The highest iron, zinc and calcium contents were found in teff–white sorghum (TwS) injera and flour. The lowest phytic acid/Fe and phytic acid/Zn molar ratios were found in barley–wheat (BW) and wheat–red sorghum (WrS) injeras. Although ideal phytic acid/Fe molar ratios (<0.4) were found in BW and WrS injeras, no significant difference between in vitro iron bioaccessibility and algorithm predicted absorption was observed. In injera, phytic acid degradation alone is unlikely to improve iron bioavailability, suggesting interactions with other absorption inhibitors. The use of phytic acid/Fe molar ratios to predict bioavailability may thus be less appropriate for iron‐contaminated foods.     

Sourdough fermentation of wheat fractions rich in fibres before their use in processed food

Fibre‐rich fractions of wheat are an important source of minerals but also contain considerable amounts of phytic acid, known to impair mineral absorption. This study explores the efficiency of wheat bran sourdough fermentation on phytate hydrolysis and mineral solubility, in comparison with whole‐wheat flour. In vitro trials were performed to assess the consequences of the addition of calcium carbonate (CaCO₃), an alkalinising salt, on phytic acid breakdown and mineral bioavailability during sourdough fermentation. Sourdough fermentation was found effective for solubilising minerals in whole‐wheat flours but was less effective with bran. In addition, sourdough acidity was blunted by the addition of CaCO₃, whereas degradation of phytic acid remained effective. Despite extensive breakdown of phytic acid (almost 70%), the addition of calcium exerted a very negative effect on zinc solubility. In conclusion, a pre‐fermentation process of whole cereals or bran, in suitable conditions of hydration, allows degradation of the major part of phytic acid and optimal mineral bioavailability. Copyright © 2007 Society of Chemical Industry     

Lactic Fermentation of Non-Tannin and High-Tannin Cereals: Effects on In Vitro Estimation of Iron Availability and Phytate Hydrolysis

The effect on iron availability estimated in vitro and phytate hydrolysis was investigated in non-tannin and high-tannin cereals, lactic fermented as flour/water slurries or gruels. A natural starter culture initiated fermentation and addition of germinated flour and phytase in the fermentation process was tested. Lactic fermentation of nontannin cereals with added flour germinated sorghum seeds or wheat phytase increased iron solubility from about 4% up to 9 and 50%, respectively. Soaking flour in water before adding starter culture had a similar effect. The increase in soluble iron was strongly related to enzymatic deeradation of phytate (p<0.001). The reduction of inositol hexa- and pentaphosphates was about 50% with added germinated flour. Reduction was > 90% after soaking the flour prior to fermentation and almost complete with 50 mg phytase added. High-tannin cereals showed a minor increase in soluble iron after fermentation, ascribed to the inhibitory effect of tannins (both on iron solubility and on enzymatic hydrolysis of phytate). Lactic-fermented cereal foods have a potential in developing countries to improve iron nutrition.     

Phytate degradation by Bifidobacterium on whole wheat fermentation

Whole cereal-based products have a beneficial effect on health, but they also contain high levels of phytate, defined as anti-nutrient. The possible use of different strains of bifidobacterial species (B. catenulatum, B. longum and B. breve) with phytate degrading activity as starters in the fermentation process was investigated. Fermentative parameters of doughs (pH, volume, total titrable acidity [TTA] and acetic and lactic acids production) and the hydrolysis profile of the phytic acid were determined during whole wheat dough fermentation. During fermentation in the presence of different bifidobacterial strains, the concentration of phytic acid showed a progressive decrease, leading to a higher release of hydrolysis products than in the control, within short fermentation time. According to the fermentative parameters bifidobacterial strains showed a good adaptation to the dough ecosystem. The range of TTA and lactic acid production was dependent on the strain. Among the tested bifidobacterial strains, those belonging to the species B. breve and B. longum induced a higher hydrolysis of phytic acid with simultaneous production of lower inositol phosphates. In addition, dough containing those strains had high pH and minor acidity than those containing a commercial starter (L. plantarum). Therefore, the tested bifidobacterial strains could be used as breadmaking starters contributing to different acidification degrees and promoting simultaneously the degradation of phytic acid in the whole wheat dough.     

放射型根瘤杆菌植酸酶对麸皮中植酸的脱磷作用

采用放射型根瘤杆菌植酸酶粗酶液水解麸皮中的植酸,研究其脱磷的最适条件。依据单因素试验和正交试验获得脱磷的最优条件为加酶量750U/g、底物质量浓度40mg/mL、温度45℃、pH7、时间5h。最优条件下,麸皮中植酸的水解率在5h达最大,为81.50%。     

Effect of soaking and phytase treatment on phytic acid,calcium, iron and zinc in rice fractions

With the aim to maximise phytic acid removal and minimise losses of dry matter and minerals (Ca, Fe, Zn) in rice, three products (whole kernels and flour milled from white and brown rice; and bran, all from the same batch of variety Kenjian 90-31) were soaked in demineralized water at 10 °C (SDW), NaAc buffer of pH 3.5 at 10 °C (SAB), and 500 U L⁻¹ phytase of pH 5.5 at 50 °C (SPS). In whole kernels and flour of white rice, phytic acid removal was 100% by all treatments; losses of dry matter, Ca, Fe, and Zn were 2–5%, 12–63%, 9–10%, and apparent gain of 63–72%, respectively. In whole brown rice, SAB removed 75% phytic acid, and SPS 100% from flour; dry matter, Ca, Fe, and Zn losses were 1–16%, 26–56%, 39–45%, and 23–24%. In rice bran, SPS removed 92% phytic acid, and SAB 50%; dry matter, Ca, Zn, and Fe losses were 20%, 48%, 63%, and apparent gain of 5%, respectively.     

加工方式对外施天然抗氧化剂面制品抗氧化能力的影响

本文研究了发酵+焙烤、发酵+蒸制、直接焙烤3种烘焙方式对添加天然抗氧化剂面制品的抗氧化能力的影响。通过在面食中添加5种天然抗氧化剂(大豆异黄酮、茶多酚、花青素、植酸、V_C/V_E),测定面食制品在加工前后的丙酮提取液对各种自由基的清除率,通过变异系数法全面评价面制品的抗氧化能力。结果表明:加工方式和添加的抗氧化剂种类是影响小麦面制品抗氧化能力的重要原因。添加大豆异黄酮的面制品用于直接焙烤能提高抗氧化性能的3.85%,添加茶多酚的面制品用于直接焙烤时抗氧化损失率最低为-3.39%,添加花青素的面制品应用于发酵+焙烤可以更好地保留其抗氧化活性,损失率为-1.77%,添加植酸和V_C/V_E的面制品应用于发酵+蒸制可以更好地保留其抗氧化能力,损失率分别为-4.66%、-5.14%。在天然抗氧化剂作为面制品添加剂时,针对不同的抗氧化剂选择最适的加工方式,能够在一定程度上改善面制品的抗氧化能力。     

Comparison of enhancement in bioaccessible iron and zinc in native and fortified high‐phytate oilseed and cereal composites by activating endogenous phytase

In developing countries, iron and zinc deficiencies are mostly attributable to poor bioavailability of iron and zinc. The study aimed at enhancing the bioaccessibility of minerals in high‐phytate oilseed and cereal flour mixes by activating the intrinsic phytase of wheat flour. The flour mixes were fortified with iron and zinc separately for comparison. The flour mixes were incubated at optimum conditions of temperature and pH for phytase activation. Phytase activation enhanced bioaccessible iron by 43–162% in native and 40–168% in fortified wheat–soya, 83–192% in native and 97–240% in fortified wheat–groundnut flour mixes in relation to control flour mixes. Bioaccessible zinc was enhanced by 87–183% in native and 30–113% in fortified wheat–soya, 31–65% in native and 61–186% in fortified wheat–groundnut flour mixes. Endogenous phytase activation was effective in enhancing bioaccessibility of iron and zinc in native and fortified flour composites economically.