Predominant yeasts in the sourdoughs collected from some parts of Turkey

In the present study, a total of eight sourdough samples were collected from three different bakeries at two different times in Turkey. Also, laboratory-scale sourdough production was conducted by daily back-slopping for 7 days. Microbiological and chemical properties of the sourdoughs were investigated. Yeast species in the sourdoughs were identified by subjecting all presumptive yeast cultures to internal transcribed spacer region amplification of the 5.8S rRNA gene, restriction fragment length polymorphism analysis using Hae III, Hha I, and Hinf I endonucleases, and sequence analysis of the D1/D2 domain of the 26S rDNA gene. A total of seven profiles were determined according to the restriction fragments. Totally, 148 yeast isolates were identified at the species level (≥400 bp , 99% identity) as Saccharomyces cerevisiae (106), Kazachstania bulderi (11), Pichia fermentans (nine), Pichia membranifaciens (eight), Kazachstania servazzii (seven), Kazachstania unispora (four), and Hanseniaspora valbyensis (three). Although collected sourdoughs were produced without using baker's yeast, S. cerevisiae was the most frequently isolated yeast species. This can be related to the contamination of the bakery environment with commercial baker's yeast during the production of other bakery products. The pH and acidity levels of the collected sourdough samples ranged from 3.71 to 3.96 and 6.78 to 23.93 mL 0.1 N NaOH/10 g dough, respectively. Mean values of the content of maltose + sucrose, glucose, fructose, lactic acid, and acetic acid were 2.43, 1.57, 2.67, 7.30, and 1.40 g/kg, respectively. Due to the artisan and region-dependent handling of the sourdough, different biochemical patterns were observed among the collected samples.     

滴定酸对苹果酒酿造的影响

用柠檬酸分别将浓缩苹果汁稀释至约 12°Bx滴定酸调节至 1 94～ 3 15 g/L(以苹果酸计 ) 5个水平 ,添加苹果酒酵母于 18～ 2 0℃发酵。随着发酵的进行 ,各发酵液的酸度升高。发酵降糖快 ,增酸速度快 ,并于发酵 3～ 4d升至峰值。过后 ,滴定酸降低 ,最终趋于稳定。成品酒滴定酸均高于对应果汁酸度。果汁滴定酸度越高 ,起发越快 ,升酸幅度越小 ,发酵后期降酸幅度也小。连二酮于发酵前期升至峰值后 ,迅速被还原至阈值以下。感官分析表明 :高发酵度苹果酒的滴定酸以 3 0 g/L左右为宜     

植烟土壤酸度调节定位试验研究

研究了石灰、白云石粉作为酸性植烟土壤改良剂对烟区土壤的改良效果及其对烤烟生长、产量和品质的影响。结果表明,隔年施用白云石粉1125kg/hm2改良土壤酸度效果明显,能促进烟株的生长;与对照相比,产量提高117.45kg/hm2,产值增加1798.05元/hm2,上等烟比例提高3.93个百分点,土壤pH从5.05升至5.36。     

磷化液总酸度的研究

引进了净总酸度的概念，在大量实验数据的基础上，利用回归统计方法，探讨了锌系磷化液中净总酸度与ＣＺｎ２＋和ＣＨ２ＰＯ－４的定量函数关系，举例说明在实际生产中的应用。     

温度、酸度对大曲酒产、质量的影响

本文从温度、酸度对大曲酒产、质量的影响，揭示大曲酒夏季＂掉排＂的主要原因为高温、高酸环境抑制了酿酒酵母的发酵，降低了酿酒酵母的发酵力，从而影响了大曲酒的产、质量。     

乳酸链球菌素在白酒发酵中的应用

乳酸链球菌素应用与白酒发酵,对降低白酒总酸,抑制白酒发酵中乳酸菌的生长繁殖,控制白酒醪液中乳酸、乳酸乙酯的生成有明显的效果。综合使用成本、控制酸度的效果等方面来看,乳酸链球菌素较佳的添加量应该是0.5mg/L,最佳的添加时间应该是投料的同时,用水稀释后均匀加入。     

Quality characteristics of strawberry genotypes at different maturation stages

The chemical composition and quality characteristics of nine promising hybrids and two varieties (“Osmanli” and “Camarosa”) of strawberries were evaluated for their quality attributes during ripening. Main soluble sugars, carboxylic acids, organic acids and ascorbic acid of experimental varieties were separated, identified and quantified using high-performance liquid chromatography with diode array spectroscopic and refractive index detections. Titratable acidity (TA), pH, total soluble solids (TSS) and TSS/TA ratio and their correlations were determined at ripe maturation stages for the 11 genotypes. Hybrid no. 11, a new strawberry cultivar, had desired fruit quality characteristics similar to Osmanli, which has a pleasant taste and is popular in Turkey.     

Chemical compositional characterization of eight pear cultivars grown in China

The sugar, organic acid, amino acid and fatty acid compounds of eight commercial pear cultivars were identified and quantified using high-performance liquid chromatography (HPLC) equipped with RI and UV detectors and gas-chromatography (GC) equipped with FID detector. The mineral composition was determined by inductively coupled plasma-mass spectrometry (ICP-MS). The results showed great quantitative differences in the composition of the pear cultivars. Fructose was the dominant sugar in the eight pear varieties, followed by glucose and sucrose, while malic acid was the principal organic acid. The C16:0, C18:0, C18:1, C18:2 and C18:3 fatty acids were clearly the most abundant fatty acids, and the C18 family comprised more than 70% of the total fatty acids content. Asparagine and serine were the principal amino acids. Potassium is the most abundant mineral, followed by magnesium and calcium. The results provide important information on how to make the best use of pear cultivars investigated for different uses, which is of significance for both technological research and processing practice.     

Quality Evaluation of Shelled and Unshelled Macadamia Nuts by Means of Near‐Infrared Spectroscopy (NIR)

The quality of shelled and unshelled macadamia nuts was assessed by means of Fourier transformed near‐infrared (FT‐NIR) spectroscopy. Shelled macadamia nuts were sorted as sound nuts; nuts infected by Ecdytolopha aurantiana and Leucopteara coffeella; and cracked nuts caused by germination. Unshelled nuts were sorted as intact nuts (<10% half nuts, 2014); half nuts (March, 2013; November, 2013); and crushed nuts (2014). Peroxide value (PV) and acidity index (AI) were determined according to AOAC. PCA‐LDA shelled macadamia nuts classification resulted in 93.2% accurate classification. PLS PV prediction model resulted in a square error of prediction (SEP) of 3.45 meq/kg, and a prediction coefficient determination value (R_p²) of 0.72. The AI PLS prediction model was better (SEP = 0.14%, R_p² = 0.80). Although adequate classification was possible (93.2%), shelled nuts must not contain live insects, therefore the classification accuracy was not satisfactory. FT‐NIR spectroscopy can be successfully used to predict PV and AI in unshelled macadamia nuts, though.     

大曲培养过程中生酸规律的研究

对酸度在大曲培养过程中的生成及变化规律进行了研究，结果表明，成品曲的酸度大小主要是在高温转化阶段生成的。高温转化阶段温度的高低及高温时间的长短，对大曲的酸度产生直接影响。在发酵阶段的后期即放风时，酸度这最大值。放风时酸度较大的，成品曲酸度相对稍高。(陶然)