Longer Fermentation Research Articles

Analisis Kimia Kopi Cherry Arabika (Coffea arabica) dengan Kajian Kadar Alkohol, Kadar Kafein, Total Padatan Terlarut dan Total Asam Pada Limbah Hasil Fermentasi Anaerobik

This study aimed to determine the quantitative measurements of alcohol concentration, caffeine content, total dissolved solids, and total acid. This study used an experimental design with a non-factorial, Completely Randomized Design (CRD) that included three treatment levels, each replicated three times. The study consists of the following treatment levels: H5 represents the fermentation of cherry Arabica coffee for five days, H10 for ten days, and H15 for 15 days. The collected data underwent analysis of variance (ANOVA) using SPSS version 22. The Duncan's New Multiple Range Test (DNMRT) was used at a 5% significance level to determine the differences in the effects of each therapy. The study showed that the length of anaerobic fermentation of Arabica coffee cherries significantly affected the concentrations of alcohol, caffeine, total dissolved solids, and total acid (p<0.05). With longer fermentation, alcohol concentration, caffeine content, and total acid levels increase while the total dissolved solids content decreases. The most effective treatment in this study was noted on the 5th day of fermentation, showing an average alcohol content of 11.93%, caffeine content of 3.36%, total dissolved solids of 4.83oBrix, and total acid of 1.62%.

Variations in Ecuadorian Cocoa Fermentation and Drying at Two Locations: Implications for Quality and Sensory.

In Ecuador, various processes are applied during cocoa post-harvesting. This study, therefore, explored fermentation parameters across two locations with 2-7 independent runs, focusing on temperature, microbial counts, pH during fermentation and drying, and their impact on cocoa bean quality. Factors including fermentation devices (jute bags, plastic bags, and wooden boxes), pre-drying, turning during fermentation, fermentation duration, and drying temperature were investigated. Fermenting in plastic bags without pre-drying or turning and fermenting in jute bags for only 40 ± 2.0 h yielded low maximal fermentation temperatures Tmax (31.1 ± 0.4 °C and 37.6 ± 1.8 °C), leading to bitter, astringent, woody, and earthy cocoa liquor. Longer fermentation (63 ± 6 h) in wooden boxes with turning (Wt) and in jute bags with pre-drying and turning (Jpt) achieved the highest Tmax of 46.5 ± 2.0 °C, and a more acidic cocoa liquor, particularly in Wt (both locations) and Jpt (location E). Therefore, it is recommended to ferment for a minimum duration from day 1 to 4 (63 ± 6 h), whether using plastic bags (with mandatory pre-drying) or jute bags (with or without pre-drying or turning). Furthermore, this study underscores the risks associated with excessively high drying temperatures (up to 95.2 ± 13.7 °C) and specific dryer types, which can falsify cut-tests and introduce unwanted burnt-roasted off-flavors in the cocoa liquor.

Changes in isoflavone profile, antioxidant activity, and phenolic contents in Taiwanese and Canadian soybeans during tempeh processing

Soybean seeds of eight different varieties were processed to tempeh. Factors affecting each step of tempeh making include isoflavone profile, FRAP (ferric ion reducing antioxidant power) and DPPH (1,1-diphenyl-2-picrylhydrazyl radical scavenging ability) assayed antioxidant activity, and TPC (total phenolic content) in the prolonged fermentation were investigated respectively. The total isoflavone contents in the dry seeds of the tested varieties ranged from 893.3 to 1386.0 μmol/100 g, and more than 99% was in the form of isoflavone glucosides. Tempeh fermentation increased the isoflavone aglycone contents by more than 20 times. Principle component analysis provided evidence of the significant correlation (p < 0.05) between isoflavone aglycone content and FRAP and DPPH assayed antioxidant activities. Molar concentration (μmol/100 g) was the preferred unit to precisely present the conversion from isoflavone glucosides to aglycones, and the total isoflavone content (μmol/100 g) was not decreased after 10 d of fermentation in most varieties. In the prolonged fermentation, daidzein kept increasing throughout but genistein decreased after day 2. For extracting a higher amount of daidzein, longer fermentation could be considered. Our results provide information of preferable fermentation periods and soybean varieties and show that tempeh may be a functional food with readily bioavailable form of isoflavones.

Role of white bread matrix components and processing parameters on 5-hydroxymethylfurfural (HMF) and acrylamide formation

This study used a full factorial design to find a good combination of 1st fermentation, 2nd fermentation, and baking time to mitigate the formation of acrylamide and HMF in white bread. Chemical characterization of bread was also performed. Trial 2 (1st fermentation, 30 min; 2nd fermentation, 60 min; baking, 20 min) showed the lowest sum of acrylamide and HMF (4281.0 μg kg −1 ) and HMF in crust (3553.5 μg kg −1 ) and in crumb (933.8 μg kg −1 ). The HMF concentration was highest in the crust fraction in all trials (3.8–5.6x highest), while for acrylamide it was highest in the crumb in most trials. Reducing the first fermentation time (30–10 min) and increasing the baking time (10–30 min) resulted in a 38.5% reduction in contaminants. Second fermentation and baking time was significant for acrylamide formation in the crust, and it was possible to obtain a valid linear model to predict the contaminant level. There was no sugar depletion in the dough, and the starch remained the same in all trials. Colour parameters were good indicators of HMF and acrylamide formation. • Longer fermentation and baking times results in higher levels of acrylamide. • A linear model was obtained for the acrylamide formation in the crust. • Changes in 1st fermentation and cooking times reduce contaminants by 39%. • This is the 1st study to compare HMF/acrylamide levels in bread's crust and crumb. • The acrylamide levels are 60x greater than those recommended by the European Union.

The influence of the japanese millet flour and the method of dough preparation on the formation of the aroma of bakery products

The article presents the results of a study of the formation of aroma-forming substances in bakery products with the addition of paize flour to the recipe. Instrumental assessment of the smell of products was carried out on the smell analyzer «MAG-8» with the methodology «electronic nose». The variants of the experiment differ in the content of paize flour 15–20%, according to the method of preparing the dough: the biological method of loosening – bread, bread sticks, unleavened dough – bread skewers. With the help of an «electronic nose», it was instrumentally proved on the MAG-8 odor analyzer that for the samples submitted for testing, the smell is correct and not pronounced, aromatic additives and odor enhancers, as well as the presence of destructive processes and mold formation are absent. When comparing the volatile compounds in the samples quantitatively, it should be noted that since the semi-finished bread undergoes longer fermentation than breadsticks, the content of alcohols and ketones is 22% higher, and compared with bread skewers, where there is no fermentation process, they are 93% more, a similar picture with acids. However, when comparing the content of individual components in samples, especially oxygen-containing compounds, they are almost twice as large in the absence of a biological method of loosening in bread skewers. For consumer evaluation, such changes are not significant for those samples in the formulation of which the content of paize flour is no more than 15% and recognized by consumers according to organoleptic indicators.

Analisis Kadar Kafein dan Antioksidan Kopi Robusta (Coffea canephora) Terfermentasi Saccharomyces cerevisiae

Robusta coffee is one of Indonesia's premier commodities known both domestic and international markets. Coffee beans are known to contain polyphenol, a flavonoid substance listed as one of the strong antioxidants, particularly chlorogenic acid (cholorogenic acid), which is one of the known resistance to free radical conditions. The study is aimed at recognizing the effect of increasing yeast and optimizing time fermentation on caffeine content and antioxidant activity on robusta coffee beans. The study is an experimental study aimed at recognizing the effects of increased yeast and longer fermentation on the characteristics of pubic coffee covering acidity (ph), total caffeine, total phenol, and antioxidal activity. Research design is a complete random design (ral). The factors noted are the five degrees of yeast concentration (k), the concentration of leaven 0% (k0), the concentration of leaven 1% (k1), the concentration of leaven 2% (k2), the concentration of yeast 3% (k3), and the concentration of yeast 4% (k4). Analysis of each treatment involves degrees of acidity, total caffeine, water level, and phytocyination test. Fingerprint analysis will show the best treatment of the effects of yeast increases and longer fermentation. Studies are expected to provide information on the best quality of fermented robusta coffee. Based on research that has been compared to the conditions of the characteristic characteristic of fermented arabic-ground coffee using s. cerevisiae with a concentration of 0%, 1%, 2%, 3% and 4% according to coffee characteristics 01-3542-2004 based on water sni 2.33-1.68% b/b, the coffee saris 301-30%35% b/b and caffeine level 1.18-1,01% b/b. The fermentation process reduces the pH and sugar reduction and the formation of ethanol.

Effects of fermentation and drying durations on the quality of cocoa (Theobroma cacao L.) beans during the rainy season in the Juaboso District of the Western-North Region, Ghana

BackgroundPostharvest treatments are crucial to the quality of cocoa finished products. This study aimed at investigating the effects of durations of fermentation and drying on the quality of cocoa (Theobroma cacao) beans during the rainy season. The study employed a 4 × 3 factorial with four fermentation durations of 5, 6, 7 and 8 days and three drying periods of 4, 5 and 6 days, resulting in a total of 12 treatment combinations, laid in a Completely Randomized Design with three replications. Bean quality data were collected on bean count/100 g, moisture content and cut test attributes including mouldy, slaty and purple, as well as percentage purity.ResultsThe study showed that the applied fermentation and drying periods single handedly resulted in moisture content higher than the recommended, coupling 8 days fermentation with 6 days drying period resulted in a moisture content of 5.6% which falls below the acceptable standard (7.5%) recommended. Number of beans/100 g increased with increasing fermentation and drying periods. Coupling any of the fermentation periods with 5 or 6 days drying duration resulted in mould content within the acceptable grade 1 limit (3%). Longer fermentation period coupled with any of the drying durations resulted in very encouraging and minimal values of purple, while coupling 6, 7 or 8 days fermentation period with 6 days drying resulted in slaty content within the grade 1 limit (3%).ConclusionThe overall effect of the treatments on the quality attributes from the cut test revealed that 8 days fermentation with the traditional leave heap method, coupled with 6 days sun drying during the rainy season, resulted in superior bean quality with a percentage purity of 98.00%.

Impact of time and temperature on the physicochemical, microbiological, and nutraceutical properties of laver kombucha (Porphyra dentata) during fermentation

Temperature and time have an important role in every fermentation process. The present study aimed to explore the effect of both temperature and time on the dynamic changes induced during fermentation on the properties of laver kombucha. Laver extracts were obtained by ultrasound-assisted extraction, and fermentation with kombucha scoby was performed at 25 and 30 °C (K-25 and K-30) for 22 days. Higher temperature promoted a faster rate of fermentation as evidenced by the lower pH, higher titratable acidity, and biofilm yield, as well as greater counts of mesophilic, and acetic acid bacteria noted in the product with lower counts of total yeast and amino acids at the end of the fermentation. Samples at a lower temperature (K-25) exhibited higher amounts of bioactive components and greater α-amylase inhibitory activity (92% in the K-25 samples vs. 83% in the K-30 samples at 14 d). In turn, longer fermentation was found to further enhance acid accumulation, showing higher acidity and lower pH, while the amount of bioactive components was reduced. These findings provide a better understanding of the dynamic changes in the characteristics of the newly developed laver kombucha based on the regulation of its fermentation conditions.

Differences in the microstructure and rheological properties of low-fat yoghurts from goat, sheep and cow milk

Goat and sheep milks have long been used to produce a range of dairy products due to their nutritional value and health benefits. Information about the microstructure and rheology of goat and sheep yoghurts, however, is scarce. In this study, the microstructure, texture and rheological properties of cow, goat and sheep yoghurts were investigated and compared. The results show that a longer fermentation and gelation time was required for goat yoghurt with a lower storage modulus compared to cow and sheep yoghurts. Cooling resulted in an increase in the storage modulus at different magnitudes for cow, goat and sheep yoghurts. Goat yoghurt had a smaller particle size and a softer gel, which is linked with a more porous microstructure. The results obtained here demonstrate the effect of different milk types on the properties of yoghurts and provide a better understanding into the link between the microstructure and physical properties of the product.

Development of Kefir beverages: Standardization of process parameters

This study aimed to characterize physico-chemically Kefir grains and standardize the process parameters of the beverages, in order to obtain an optimum product. Kefir grains consisted basically of water (85.61 ± 0.41%) and had an acidic pH (4.45) and low acidity (0.44 ± 0.09% lactic acid). To determine the process parameters, it was used a 23 factorial design with three replications at the central point, being evaluated the amount of grain (2-6%), amount of sugar (10-14%) and fermentation time (18-24 hours) at 25oC. The amount of sugar or grains had no influence on the pH and titratable acidity. A longer fermentation time (24 hours) resulted in products with pH and acidity within the recommended values, while fewer grains (2%) did not result in too firm beverages. The formulation with the best physicochemical and sensory characteristics had 2% grain, 10% sugar and 24 hours of fermentation, being described as creamy, slightly acidic and with intermediate sweetness.

Physico-chemical properties of Wikau maombo flour from cassava (Manihot esculenta Crantz)

Wikau maombo flour has a great potential as an economical food products in Southeast Sulawesi. The aims of this study were to apply the traditional methods of cassava flour manufacturing process roomates including peeling, washing, the immersion of sea water, fermentation, drying, milling and analyze the characteristic of wikau Matombo flour. The cassava was immersed for 24 h in sea water prior to fermentation in 1–4 days. Fermented flour in 3 days is the choosen product due to its good organoleptic and mass-produced analysis. The cyanide content of the flour was 2.7 mg/kg, whereas the content of carbohydrate, protein, fat, ash, moisture and crude fiber were 87.69 ± 0.1, 2.4 ± 0.1, 0.34 ± 0.02, 1.04 ± 0.59, 6.23 ± 0.48 and 2.30 ± 0.72 %, respectively. FTIR analysis showed that the intensity of peaks in 1016, 1150, 1650, 2990 and 3390 cm−1 were found to decrease with a longer fermentation. Based on the XRD analysis, the crystallinity of Wikau maombo flour decreased as the fermentation time increase. With a long fermentation, the morphology of the flour was observed as irregular granules with starch granule size. The physicochemical properties of wikau Matombo flour including swelling power, crystallinity, solubility, cyanide content, viscosity, pasting temperature, pH and granule size were 8.39 ± 0.06 g/g, 24.41 %, 66 ± 0.27 %, 2.7 ± 0.03 mg/kg, 4061cP, 74.1 °C, 6.5 ± 0.05 and 5–15 μm, respectively.

The stakiosa and essential fatty acids biochemical changes in soybean tempeh (Glycine max) during fermentation process.

Triwibowo R, Andriani M.A.M., Ariviani S. 2016. The stakiosa and essential fatty acids biochemical changes in soybean tempeh (Glycine max) during fermentation process. Bioteknologi 13: 34-41. Soybean tempeh is a food that is known by the people of Indonesia. It is known to have levels of stakiosa which causes flatulensi lower than soybean. It is also known to have levels of essential fatty acids (oleic acid, linoleic, and linolenic), which is higher than soybean. This study aims to determine changes in levels of stakiosa and essential fatty acids (oleic acid, linoleic, and linolenic) during the fermentation process. The determination of stakiosa used High Performance Liquid Chromatography method (AOAC 1999). The determination of essential fatty acids include oleic acid, linoleic, and linolenic used Gas Chromotograpy method (Park and Goins 1994). This research are expected to provide an alternative optimal fermentation time observed from the lowest level of stakiosa and the high level of essential fatty acid. The results showed that stakiosa levels of soybean tempeh decreased over the longer fermentation. The percentage of the highest decrease level of stakiosa found in 24 hours fermentation. While changes in level of oleic acid, linoleic acid, and linolenic acid in soybean tempeh fermentation for 96 hours has the same pattern. The lowest level of essential fatty acids found in 48 hours fermentation time and the highest in 96 hours fermentation.

Dynamic Viscosity and Activation Energy of Wort During Fermentation and Storing

This paper presents the results of wort dynamic viscosity and activation energy during fermentation. The effect of temperature and storing time on both parameters was investigated. Measurements were performed on two wort samples. The first sample was taken at the beginning of fermentation, and the second sample after three hours of fermentation. Both samples were also measured after three weeks of storing. Dynamic viscosity measurements were performed with a digital rotational viscometer Anton Paar DV-3P, the principle of which is based on the dependency of sample resistance to probe rotation. Results of measurements are shown as graphical dependencies of both analysed parameters on temperature. The temperature dependence of dynamic viscosity can be characterised by a decreasing exponential function, while in case of activation energy linear increasing characters were obtained. Longer fermentation and storing period caused a decrease in both analysed parameters, due to the structural changes in wort samples during fermentation and storing.

Manufacture of a beverage from cactus pear juice using “tea fungus” fermentation

Kombucha is a beverage that is prepared by fermenting sweetened black tea using a tea fungus, which is a symbiotic culture of acetic acid bacteria and yeasts. In the present study, cactus pear juice was used as a substrate for kombucha fermentation in order to develop a new beverage with enhanced nutritional properties. Changes in chemical and microbiological parameters of the fermented juice were determined during fermentation. The growth of microflora induced a reduction in pH from 5.1 to 3.5 and a 23 % increase in total phenol content after 6 days of fermentation. The antioxidant potential of the beverage was also improved, reaching 81 % and 65 % as determined, respectively, by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6- sulfonic acid) (ABTS) radical scavenging assays. The improved antioxidant capacity was attributed to betalains and to certain metabolic products formed during the fermentation process. Furthermore, the fermented juice showed antimicrobial activity against the tested Gram-positive (Staphylococcus aureus ATCC 6538, Bacillus cereus ATCC 11778, Staphylococcus epidermidis ATCC 12228 and Enterococcus faecalis ATCC 10541) and Gram-negative bacteria (Escherichia coli ATCC 10536, Klebsiella pneumoniae ATCC 10031, and Pseudomonas aeruginosa ATCC 9027), which was attributed to its acetic acid content. Sensory evaluation of fresh juice and juice after 6 and 12 days of fermentation by a taste panel showed high acceptability of the juice after the first 6 days of fermentation, as the cactus pear juice taste qualities were still present, without the higher acidity that some panelists found unacceptable after longer fermentation.

Production of Kefiran in Kefir Grains and its Effects on the Rheological Properties Low Protein Wheat Dough and Quality of France Bulky Bread

Kefiran is an exogenous microbial metabolite which is produced principally by lactic acid bacteria and fungi and molds throughout growth. Exo polysaccharide of kefiran was extracted from kefir grains and in status of gel was added at 1, 2, 3% concentrations (w/w flour basis) to wheat flour to evaluate its effects on rheological properties of weak wheat dough. The rheological measurements of the dough were investigated using Farinograph and Extensograph instruments. Results of Farinograph evaluation of dough showed that adding of kefiran and increase in its levels leads to increase in the water absorption capacity, dough development time and departure time, while the dough degree of softening after 20 min and mixing tolerance index were decreased in comparison with the control sample. The study on Extensograph behavior of the dough containing kefiran showed that resistance to extension at 45 and 90 min resting times was increased by increasing the percentage of the added kefiran. Longer fermentation time for each level of kefiran led to decrease of resistance to extension. Significant difference was observed in the resistance to extension of the dough containing different levels of kefiran and the control sample. Addition of kefiran to the dough after 45, 90 and 135 min resting times significantly decreased the extensibility, also with an increase in resting time from 45 to 135 min, the extensibility decreased for both the control and kefiran samples. Generally, addition kefiran at 45, 90 and 135 min resting times led to a significantly increase in resistance to extension ratio. Energy input increased at 45 and 90 min resting times, whereas chaotic effect was shown at time of 135 min restig time. Therefore, kefiran can be used to playing an important role in improving of rheological properties of weak dough and its processing conditions.

비지 koji 첨가에 따른 양조간장의 발효 중 이화학적 특성 평가

To evaluate the practical use of okara koji in soy sauce fermented with soybean koji, the okara koji was fortified with different contents (0, 50, and 100%) in soybean koji and then fermented for 90 days. The saltiness of the soy sauce was about 17.15~17.22%. The higher okara koji content showed lower net soluble solid contents of 8.73, 6.12, and 2.50%, as well as lower acidity levels of 1.09, 0.98, and 0.47%. The buffering capacity of the soy sauce decreased to 1.26-3.41 by adding higher okara koji. The protease activity was higher in the soy sauce with 50% orara koji and decreased with longer fermentation. Also, the tyrosine content peaked to 275.2 mg% after 90 days. -amylase showed higher activity in the soy sauces fortified with okara koji, which resulted in the highest total sugar and reducing sugar contents after 60 days. The total sugar and the reducing sugar in the soy source decreased after longer fermentation. The total free amino acid contents of the soy sources fortified with okara koji (0, 50, and 100%) were 41.68 mg/mL, 33.10 mg/mL, and 9.27 mg/mL, respectively. In particular, the glutamic acid contents of the three types of soy sauces were highest, and most amino acids, except for glutamine, increased during the fermentation for 90 days. The sensory evaluation, except of the saltiness and color, showed similar values in the soy sauces, except in the okara koji 100%. Thus, okara koji could be a valuable ingredient of traditional soy sauces. However, the 50% okara koji did not differ significantly from the others.

Effect of Lactic Acid Bacteria Fermentation on Rosmarinic Acid and Antioxidant Properties of in vitro Shoot Culture of Orthosiphon aristatus as a Model Study

In vitro shoot culture of Orthosiphon aristatus was selected as a model system for lactic acid bacteria (LAB) fermentation study. This in vitro plant was subjected to different types of LAB fermentations (Lactobacillus plantarum ATCC 8014 and Lactobacillus acidophilus NCFM) for a different time periods of 24, 48, and 72 h at 37oC. The LAB fermentations consisted of solid state fermentations in a climatic incubator and liquid state of fermentations in a DCU fermenter system. The aim was to determine the effect of fermentation on antioxidant properties of the in vitro plant extract. Results indicate that all types of LAB fermentation decreased the level of rosmarinic acid and total phenolic compounds; however, a slight increase in total flavonoids and flavonols was observed in solid state fermentations samples. The highest reduction was obtained in the sample of liquid state fermentation inoculated with L. plantarum for a period of 72 h. The loss in rosmarinic acid and phenolics was concomitant with a loss of total antioxidant activity (DPPH, TEAC, and SOD-like activity). HPLC result confirmed that the longer fermentation was the greater reduction phenolic acids content was found. These results indicate LAB fermentation caused a decrease on antioxidant properties of in vitro shoot culture of Orthosiphon aristatus.

Influence of size reduction variation and fermentation time towards cyanide acid contents and phenolic compound in faba bean (Vicia faba) tempeh

Indriyani CS, Handayani S, Rachmawati D. 2010. Influence of size reduction variation and fermentation time towards cyanide acid contents and phenolic compound in faba bean (Vicia faba) tempeh. Biofarmasi 8: 31-36. Tempeh is fermentation product wich very known by Indonesian society and has been familiar with various western society. Tempeh can be made from various ingredient, but usually, tempeh is made from soybean. Due to the increasing soybean price, it has been found another Leguminosae to substitute soybean. One of legume was faba bean, Leguminosae, that generally contains phenol as antioxidant and cyanide acid as antinutrient and toxic material. The aim of this research was to determine the effect of size reduction variation and fermentation time variation of faba beans tempeh production to cyanide acid and total phenol contents. This research used a factorial experiment that arranged in a Randomized Complete Design (RCD) with two experimental factors including size reduction (chopped and sliced) and the time of fermentation (0, 30, 36, 42 and 48 hours). The result showed that cyanide acid content in fermentation of 0, 30, 36, 42 and 48 hours on faba beans tempeh by chopped seeds were 0.060 mg/g, 0.048 mg/g, 0.036 mg/g, 0 mg/g and 0 mg/g, respectively, then on faba beans tempeh by sliced seeds were 0.072 mg/g, 0.036 mg/g, 0.036 mg/g, 0 mg/g and 0 mg/g, respectively. Meanwhile, the content of total phenol on faba beans tempeh by chopped seeds were 0.014750%, 0.149900%, 0.201825%, 0.170400% and 0.234400%, while on faba beans tempeh by sliced seeds were 0.014750%, 0.152650%, 0.178300%, 0.162750% and 0.192620%, respectively. The fermentation time and the size of faba beans seeds affected on cyanide acid and total phenol contents of faba beans tempeh. The longer fermentation time of faba beans tempeh caused lower cyanide acid content and higher total phenol content. The smaller size of faba beans seeds on tempeh caused lower cyanide acid content and higher total phenol content. The lowest cyanide acid content was contained in faba beans tempeh with chopped and sliced seeds with 42 and 48 hours fermentation reached 0 mg/g. The highest total phenol content was contained in chopped faba beans tempeh with 48 hours fermentation reached 0.234400%.

Morphology and physicochemical changes in rice flour during rice paper production

Rice flour samples from four steps of rice paper processing were prepared from rice grain, Chainart 1 variety: wet-milled flour (WMF), 24 hour soak-milled flour (24SF), 48 hour soak-milled (48SF), and dried rice paper (DRP). Decrease in protein, fat and amylose content occurred during prolonged fermentation but increase of ash content due to addition of salt occurred. Because of lactic acid bacteria activity, increases occurred in titratable acidity as lactic acid in soaking water during fermentation. Scanning electron microscopy revealed that starch granule surfaces wilted and showed corrosion channels with longer fermentation. Pasting and thermal properties of the four samples were significantly different; 24SF and 48SF showed lower peak viscosity, breakdown and final viscosity. Increasing fermentation time increased gelatinization temperature, endothermic energy and relative crystallinity. The results suggest that lactic acid and enzyme hydrolysis during fermentation in rice paper processing caused significant decrease in amorphous structure and increase in crystallinity in rice starch.

Studies on the interaction of fermentation and microfiltration operations: erythromycin recovery from Saccharopolyspora erythraea fermentation broths.

Changes in fermentation media not only affect the performance of the fermentation itself (with regard to the kinetics of biomass and product formation and the yields obtained) but also the initial product-recovery operations downstream of the fermentor. In this work, microfiltration experiments to remove Saccharopolyspora erythraea biomass from fermentation broth and to recover erythromycin were carried out using two fundamentally different media; a soluble complex medium (SCM) and an oil-based process medium (OBM). Small-scale batch fermentations of 14-L working volume were carried out in triplicate using both media. Broth samples were taken from each fermentation at regular intervals from the end of the exponential-growth phase onwards. These were then processed using a Minitan II (acrylic), tangential crossflow-filtration module, fitted with a single 60 cm(2) Durapore hydrophilic 0.2 microm membrane, operated in concentration mode. The OBM fermentations produced higher titers of erythromycin but required longer fermentation times due to increased lag phases and slower maximum-growth rates. The OBM also increased the loading on the membrane; at maximum product titers residual oil concentrations of 3 g. L(-1), antifoam concentrations of 2 g. L(-1) and flour concentrations estimated at approximately 10 g/L(-1) were typical. It was found that both the permeate flux and erythromycin transmission were affected by the choice of medium. The OBM had significantly lower values for both parameters (12.8 Lm(-2) h(-1) and 89.6% respectively) than the SCM (35.9 Lm(-2) h(-1) and 96.7% respectively) when the fermentations were harvested at maximum erythromycin titers. Transmission of erythromycin stayed approximately constant as a function of fermentation time for both media, however, for the OBM the permeate flux decreased with time which correlated with an increase in broth viscosity. The relatively poor microfiltration performance of the OBM medium was, however, offset by the higher titers of erythromycin that were achieved during the fermentation. The filtration characteristics of the SCM broth did not show any correlation with either broth viscosity or fermentation time. Image-analysis data suggested that there was a correlation between hyphal morphology (main hyphal length) and permeate flux (no such correlation was found for the OBM broth). Moreover, it has been shown for the OBM broth that the residual flour had a profound effect on the microfiltration characteristics. The influence of the residual flour was greater than that imposed by the morphology and concentration of the biomass. The understanding of the factors governing the interaction of the fermentation and microfiltration operations obtained in this work provides a first step towards optimization of the overall process sequence.