The comparative ability of four isolates of Bacillus subtilis to ferment soybeans into dawadawa

In an attempt to develop starter cultures for fermenting soybeans into the traditional West African condiment dawadawa, four isolates of Bacillus subtilis: 24BP(2), 72RP(17), 72BP(30), and FpdBP(2), which had been selected from 42 Bacillus cultures in a previous study by the current authors, were used separately to produce soy-dawadawa. The accompanying microbiological and biochemical changes, including enzymatic activities, as well as the organoleptic quality of the products were evaluated including that of a control sample which was fermented spontaneously. Significant differences existed in the ability of the four isolates to hydrolyse the soybean proteins, starch, and fat to produce dawadawa. Bacillus subtilis 24BP(2) recorded the highest protease and amylolytic activities, 101 U/ml and 26.68 mg/ml, respectively, and liberated the most amino acids, 117.64 mg/g dry wt., during fermentation. Bacillus subtilis 24BP(2) also grew to the highest population of cells in the final product. Taste panelists found soybean dawadawa produced by each of the four isolates acceptable and rated soup flavoured with soy-dawadawa produced by Bacillus subtilis FpdBP(2) as the best sample. Panelists scored it higher than the control sample and soy-dawadawa produced by Bacillus subtilis 24BP(2) in that order.     

Screening of 42 Bacillus isolates for ability to ferment soybeans into dawadawa

Forty-two cultures of Bacillus species isolated from soybean dawadawa were screened for their proteolytic activity on Skim Milk Agar, amylolytic activity on Starch Agar, and ability to grow on Soybean Agar. Distinct differences were observed between the cultures for all the criteria. Eleven isolates were selected for laboratory fermentation trials and each produced soybean dawadawa which was found acceptable by a taste panel. The pH of the samples, which increased from 6.37-6.58 to 8.22-8.85 during fermentation, were significantly different at P< or =0.05 for the different cultures. In the fermented samples, Bacillus counts exceeded 10(9) cfu/g, with the population of only one sample being significantly different at P< or =0.05. A market focus group familiar with soybean dawadawa selected Bacillus subtilis 24BP(2) and B. subtilis FpdP(2) as the best potential starter cultures. A taste panel found no significant differences in overall acceptance between soybean dawadawa either fermented spontaneously or with B. subtilis 24BP(2) and also between soybean dawadawa fermented with either B. subtilis 24BP(2) or B. subtilis FpdP(2).     

Flavouring composition prepared by fermentation with Bacillus spp

Fermented foodstuffs and condiments remain a key constituents of diets throughout many parts of Asia and Africa. In cases where the process of fermentation evolved for the development of taste or aroma, it often resulted in enhanced nutrition, stabilisation of the original raw materials, and detoxification of anti-nutrient factors. Several fermented products rely on the participation of various Bacillus species, including Bacillus natto and B. subtilis. Often, the finished products are of a very local character and exhibit sensory properties resulting from unique flora and processing technologies applied in small scale, home-based fermentations. Fermentation with B. natto and B. subtilis can produce very characteristic aromas in fermented products such as natto and dawadawa (also referred to as daddawa). Moreover, the hydrolytic capabilities of these microorganisms can result in a precursor-rich environment, which is useful for subsequent reactions leading to flavour production. A 1995 patented process demonstrated the ability to produce a fermented flavouring composition with the use of Bacillus spp. Hydrolysed protein obtained after fermentation with Bacillus spp. is mixed with reactive flavour precursors, which are subsequently heated to induce flavour formation and can be dried to a powder format. The product of this patented process imparts a basic meaty flavour, with a reduced yet characteristic dawadawa-like aroma. This paper briefly summarises some of the characteristics and uses of traditional dawadawa and illustrates alternatives described in the patent for the production of a process flavour base. Issues and considerations for the industrialisation of a fermentation process are briefly discussed, as well as some future opportunities for development and exploitation of traditional fermentation technology.     

Effect of Processing on Certain Antinutrients in Bambara Groundnut (Vigna subterranea) Cotyledons

Cotyledons of two Nigerian varieties of bambara groundnut were analysed for trypsin inhibitor activity (TIA) and polyphenols after whole beans had, in each case, been cold-soaked, hot-soaked, cold-soaked/germinated and dehulled. Another portion of beans was fermented after they had been cold-soaked, dehulled and boiled for 10 min (pretreatment), simulating the ‘dawadawa’ process. Germination made dehulling of the beans very easy, as the hulls broke open during the process, but was not very effective in reducing the polyphenol levels (9%, average loss) and TIA (17%, average loss). The combined pretreatment/fermentation process reduced the polyphenol level and TIA by 24% and 40%, respectively (average losses). Hot-soaking considerably improved the dehulling properties of the beans over cold-soaking and was more effective in reducing the TIA level in the cotyledons (31%, average loss) than cold-soaking (12%, average loss). Polyphenol losses by the two conditioning methods were similar (9%, average). Generally, losses in polyphenols and TIA could be attributed to leaching and inactivation respectively during the processes involved. The results show that a combination of two or more simple processing methods could be used to improve the food value of bambara groundnut. © 1997 SCI.     

枯草芽孢杆菌分离鉴定及其对烟叶化学成分和吸味品质的影响

为研究枯草芽孢杆菌对烟叶化学成分和吸味品质的影响,从初烤后烟叶中筛选出一株微生物（H11）,结合菌株形态和16S rDNA序列分析,初步鉴定为枯草芽孢杆菌枯草亚种（Bacillus subtilis subsp. subtilis）;用H11对20 kg河南平顶山低等级烟叶（2017 DCFB）发酵30 h,对比分析发酵前后烟叶感官质量、常规化学成分、中性香味成分的变化,并采用宏基因组测序技术,分析了发酵前后烟叶表面微生物群落变化,探讨了酶在烟叶发酵中的作用。与发酵前相比,烟气透发性好、甜感增强、香气质提升、香气量增加;水溶性总糖和还原糖含量（质量分数）分别增加了2.52%和1.92%;（E）-β-大马酮、二氢猕猴桃内酯和巨豆三烯酮C等香味成分含量（质量分数）分别增加了25.92%、10.57%和12.15%;烟叶表面微生物数量明显减少,芽孢杆菌属（Bacillus）微生物丰度增加至微生物总量的76%。枯草芽孢杆菌（Bacillus subtilis）对烟叶化学成分和吸味品质有重要影响,且具有发酵时间短和处理量大等特点,可为微生物发酵低等级烟叶提供参考。      

桌布法结合极化投影地图法剖析葵花籽油香味特征

目的 研究中国市场上以及不同炒籽条件制得的葵花籽油感官特性,剖析葵花籽油香气特点并划分香气类型。方法 联合使用桌布法（Napping）和 极化投影地图（Polarized Projective Mapping,PPM）等剖析了19款小试加工工艺生产的自制以及7款市售的商品等26款葵花籽油的香味特征。结果 （1）经过培训的评价小组使用Napping和PPM方法均可以快速、良好地对多款葵花籽油样品进行评价;（2）PPM方法可以获得与Napping方法相似的结果,26款样品均被分为4种香型,主要特点依次为生瓜子、甜香（炒瓜子）、焦糊和油炸方便面;（3）在PPM实验中,评价员能够将样品进行更精细的区分。结论 Napping和PPM这两种新型感官分析方法在评价葵花籽油香气方面有良好的适用性,建立了葵花籽油描述词库,并将葵花籽油分为生瓜子型、甜香型（炒瓜子）、焦糊型和油炸方便面型等四种香气类型,可为葵花籽油等植物油产品开发、技术改进及质量评价等提供参考。     

Processing Effects on Chemical,Functional and Pasting Properties of Cowpea Flour from Different Varieties

Cowpea varieties (IT88D-867-11, IT89KD-288 and MALA) were boiled, roasted, dehulled and later milled into powder. The proximate composition, functional and pasting properties as well as anti-nutritional contents (Tannin) of the product was subsequently determined. The result of the study revealed significant increase (P < 0.05) in the crude protein, crude ash, swelling power and water absorption capacity. Conversely, significant decrease (P < 0.05) was observed in crude fat, starch content, moisture content, solubility and peak viscosity. Boiled samples have significantly higher (P < 0.05) crude protein, swelling power, water absorption capacity, with concomitantly lower solubility and tannin content. Crude ash, moisture, solubility and tannin content of dehulled samples decreased significantly with an increase in protein, swelling power and water absorption capacity. However, IT89KD-288 has the highest protein content irrespective of the processing used. But raw IT89KD-288 showed highest percentage of swelling power, solubility, water absorption capacity and Tannin content. The result revealed that both boiling and dehulling will greatly reduce tannin content of cowpea.     

纳豆腐乳发酵工艺优化

以腐乳半成品为试验材料,以感官评价和纳豆枯草芽孢杆菌菌落数为评价指标,采用单因素试验和正交试验设计确定并优化了纳豆腐乳的发酵工艺。结果表明,最佳发酵工艺为大米添加量9%、纳豆枯草芽孢杆菌接种量5%、发酵前16 h温度为37 ℃,后8 h为50 ℃、发酵相对湿度为60%。在此最佳条件下制备的纳豆腐乳具有白腐乳应有的滋味和香气,氨基酸态氮含量可达0.44 g/100 g,纳豆枯草芽孢杆菌菌落数为1.63×108 CFU/g、食盐含量低于6.4 g/100 g、纳豆激酶酶活可达2 712 FU/g,具有溶血栓效果,是一种新型特色腐乳,具有广泛的市场应用前景。     

Sensory characteristics and volatile components in aromas of boiled prawns prepared according to experimental designs

Comparing samples prepared according to a two-level fractional-factorial design, parts of prawns and pH were selected as essential factors for generating boiled prawn aroma. Aroma characteristics in samples prepared based on a three-level full-factorial design for pH (2, 7, and 12) and parts (shell: S, meat: M, and meat with shell: W) were quantitatively described using 10 attributes. “Sweet”, “cooked fish”, “roasted shrimp” and “boiled prawn” scores were higher in M and W samples at pH 7, but “sewage” scores were higher in all S samples. Response surfaces in statistically significant models obtained for seven attributes clearly visualized how parts and pH influenced them. Partial least squares regression models composed of selected influential peaks for seven attributes were highly predictable.     

菌种接种方式对黄豆酱品质的影响

以沪酿3.042米曲霉、AS 3.35黑曲霉、AS 3.324甘薯曲霉、沪酿3.130毛霉、AS 3.972红曲霉、米根霉和枯草芽孢杆菌为菌种进行制曲、发酵,通过测定发酵7 d后蛋白酶活力和氨基酸态氮含量,研究单菌种制曲发酵、曲料混合发酵和多菌种混合制曲发酵方式对黄豆酱品质的影响。结果表明:曲料混合发酵产蛋白酶活力和氨基酸态氮含量效果最好,其次为多菌种混合制曲发酵和单菌种制曲发酵。曲料混合发酵和多菌种混合制曲发酵中,2菌种和3菌种组合产蛋白酶活力和氨基酸态氮含量整体较高,其中曲料混合发酵5号(沪酿3.042米曲霉、AS 3.35黑曲霉和枯草芽孢杆菌)产蛋白酶活力和氨基酸态氮含量最佳,分别达到713 U/mL和0.89 g/100 g。研究发现,沪酿3.042米曲霉成曲、AS 3.35黑曲霉成曲和枯草芽孢杆菌成曲按照曲料混合发酵方式接种更有利于得到品质较优黄豆酱。     

炒制青稞及燕麦香气组成差异研究

为探究青稞和燕麦炒制后挥发性风味成分的差异,采用气相色谱-质谱联用技术(GC-MS)对青稞和燕麦炒制样挥发性成分进行了分离鉴定。结果表明:青稞共检出64种香气成分,包括杂环类(25种)、酯类(10种)、醛类(8种)等;燕麦共检出97种香气成分,包括杂环类(16种)、醇类(18种)、醛类(15种)等。炒制青稞杂环类化合物种类与相对含量显著高于炒制燕麦,而炒制燕麦中其他类型香气物质种类与相对含量则明显高于前者。香气分析显示,炒制燕麦香气更为复杂,其果香、油脂香、坚果香等分布较均衡;而炒制青稞中坚果香、可可香、烤香等特征香气更为突出,其他香气相对较弱。     

Effect of local processing methods (boiling,frying and roasting) on the amino acid composition of four marine fishes commonly consumed in Nigeria

The effects of different processing methods on the amino acid contents of four marine fishes commonly consumed in Nigeria: Clupea harengus, Scomber scombrus, Trachurus trachurus and Urophycis tenuis were investigated. The samples were boiled, roasted over hot charcoal, or fried in any of four different oil types (palm oil, soybean oil, vegetable oil and groundnut oil). The total amino acids for all the fish samples ranged from 76.72 to 98.01 g/100 g protein and the total essential amino acids from 28.95 to 44.73 g/100 g protein. Frying reduced the total amino acid contents, with the lowest values obtained in samples fried in palm oil. Boiling and roasting increased the total amino acid contents, with the values higher in roasted than boiled samples. The percentage of essential amino acids reduced with processing in almost all samples, but the reduction was more pronounced in the fried samples. The raw, boiled and roasted samples had amino acid scores greater than 100%, while for the fried samples, the limiting amino acids were either leucine or threonine. The results showed that roasting and boiling had more desirable effects on the amino acid content of the fish samples.     

响应面法优化小龙虾烤箱辅助烤制工艺

以小龙虾为研究对象,探讨烤箱烤制小龙虾的加工工艺,以腌制时间、腌制液盐含量、烤制温度和烤制时间为单因素影响因子,小龙虾的感官评分和弹性为响应值,进行响应面优化分析。然后对烤制小龙虾的营养成分和风味特征进行测定和分析,并以鲜虾和水煮虾作为对照。结果表明：经优化后的小龙虾腌制时间为30 min、腌制液盐含量12 g/100 mL、烤制温度180℃、烤制时间20 min,在此工艺条件下小龙虾的感官评分为9.08分、弹性为3.88 mm,与预测值接近,表明该烤制工艺合理有效;烤制处理条件下单不饱和脂肪酸和多不饱和脂肪酸总含量显著高于鲜虾和水煮虾;烤制之后的小龙虾必需氨基酸和风味氨基酸含量较鲜虾和水煮虾差异明显,主要表现在天冬氨酸、甘氨酸、精氨酸和亮氨酸的损失,其中精氨酸损失最大;电子舌传感器上的烤虾响应值鲜度、咸味和甜味均显著高于鲜虾和水煮虾。适当的烤制有利于虾肉营养物质的保存和鲜香味的挥发,同时有利于产品营养与风味的提高。     

Investigating Influence of pH and Parts on Sensory Characteristics and Volatile Components in Boiled Squid Using Experimental Designs

ABSTRACT: The aroma property of boiled squid was quantitatively described using 10 sensory attributes. From screening experiments based on a Plackett-Burman design, pH and parts of squid were selected as significant factors for generating the "cooked squid" aroma. Squid samples prepared according to a 3-level full-factorial design for pH and parts showed that "sweet,""roasted shrimp,""cooked fish," and "cooked squid" scores were higher in both muscle and muscle with skin at pH 6.5. Response surface models calculated for each of the attributes showed how pH and parts influenced their strength. Partial least squares regression analysis applied to the sensory and GC-MS data revealed that every attribute could be predictable (R²≥ 0.956) using a small number of informative peaks.     

Profiles of volatile compounds and sensory characteristics of Robusta coffee beans roasted by hot air and superheated steam

Although superheated steam (SHS) roasting has proved to be capable of improving selected quality of roasted Robusta coffee beans, impact of SHS roasting on aroma characteristics of the beans is not well understood. This study therefore aimed to investigate the effect of SHS roasting on aroma profiles and sensory characteristics of Robusta beans undergone SHS roasting at 190–250 °C; results were compared with those of beans roasted by hot air (HA). Sensory characteristics of selected samples were also compared with HA-roasted Arabica beans. Forty five aroma compounds were identified; most were fully developed in beans roasted at 230 °C and tended to degrade in beans roasted at 250 °C. SHS roasting led to more extensive formation of aroma compounds contributing to caramel note, while helped reduce formation of major contributors to spicy, roasty and burnt notes. SHS-roasted Robusta beans exhibited more resemblance to Arabica beans than their HA-roasted counterpart.     

板栗加工工艺对挥发性香气成分的影响

板栗经过不同的加工工艺熟化后会产生不同的风味。文中分别对生板栗,以及煮制、炒制和烤制加工后的板栗进行ATD热脱附以及GC-MS分析,得出不同加工工艺条件下的板栗挥发性香气成分。其中生板栗主要有板栗本身的草本清香香气成分,如乙酸乙酯、己醛、乙酸丁酯、3-甲基-1-丁醇乙酸酯、α-蒎烯和苯甲醛等;炒板栗和烤板栗的特征性挥发物有2-戊基呋喃、3-蒈烯、4-羟基-2-丁酮和2-甲基-四氢呋喃-3-酮;煮板栗中发现了之前未在板栗香气研究中报道过的香气成分螺[2,4]庚-4.6-二烯。     

The effects of processing methods on the levels of lysine, methionine and the general acceptability of ogi processed using starter cultures

Batches of ogi were produced from maize flour slurry, dehulled maize grains and whole maize grains using Saccharomyces cerevisiae and Lactobacillus brevis as starter cultures. Fermentation over time showed that dehulled maize grains inoculated with the starter cultures and processed whole maize grains requiring steeping led to higher acid production than fermentation with dry-milled maize slurry. Ogi from dehulled maize grains inoculated with starter cultures showed the highest levels of lysine and methionine. Steeping grains encouraged a stronger ogi aroma than fermentation of maize flour slurry alone. Lactobacillus brevis contributed most to the taste of ogi. Fermentation with starter cultures showed good prospects for improving the lysine and methionine levels of ogi.     

Extraction,identification and semi-quantification of oligopeptides in cocoa beans

Peptides and amino acids generated during cocoa bean fermentation are known to be the most important precursors for the development of cocoa aroma. Although cocoa fermentation and aroma development have been extensively studied, the cocoa oligopeptide fraction is under-investigated. In particular, the identification of specific peptide sequences and the quantification of cocoa peptides are scarce in the literature. The aim of this study was to investigate the presence of oligopeptides in fermented cocoa beans. Peptides were analysed by reversed phase LC/ESI-MS and LC/ESI-MS/MS, and the molecular masses of 44 different peptides were obtained by analysing the mass spectra associated with the most intense chromatographic peaks. Peptides were identified based on the exact molecular masses, mass fragmentation patterns and by comparison with vicilin and 21 kDa cocoa seed protein sequences. Semi-quantitative data on peptide presence in fermented cocoa samples of different geographic origin, different fermentation levels and on roasted products were also provided.     

The influence of salt and temperature on the natural fermentation of African locust bean

Variations in salt (NaCl) content and temperature influenced the microbial development and organoleptic quality of fermenting African locust bean (Parkia filicoidea Welw.) seeds. The influences on microbial growth by different salt contents and temperatures were followed by changes of pH and titratable acidity. A 1% (w/w) salt addition and fermentation at 37 degrees C improved the organoleptic quality of the product. Salt additions above 3% (w/w) and temperatures below 25 degrees C resulted in lower microbial counts, low pH and titratable acid values; fermentation of the processed substrate of African locust bean seeds was inhibited and the organoleptic quality was poor. The predominant microorganism present throughout the fermentation was a Bacillus sp. with characteristics similar to Bacillus subtilis.     

Kefir Immobilized on Corn Grains as Biocatalyst for Lactic Acid Fermentation and Sourdough Bread Making

Abstract: The natural mixed culture kefir was immobilized on boiled corn grains to produce an efficient biocatalyst for lactic acid fermentation with direct applications in food production, such as sourdough bread making. The immobilized biocatalyst was initially evaluated for its efficiency for lactic acid production by fermentation of cheese whey at various temperatures. The immobilized cells increased the fermentation rate and enhanced lactic acid production compared to free kefir cells. Maximum lactic acid yield (68.8 g/100 g) and lactic acid productivity (12.6 g/L per day) were obtained during fermentation by immobilized cells at 37 °C. The immobilized biocatalyst was then assessed as culture for sourdough bread making. The produced sourdough breads had satisfactory specific loaf volumes and good sensory characteristics. Specifically, bread made by addition of 60% w/w sourdough containing kefir immobilized on corn was more resistant regarding mould spoilage (appearance during the 11^th day), probably due to higher lactic acid produced (2.86 g/Kg of bread) compared to the control samples. The sourdough breads made with the immobilized biocatalyst had aroma profiles similar to that of the control samples as shown by headspace SPME GC‐MS analysis.