Post-harvest pod storage: A method for pulp preconditioning to impair strong nib acidification during cocoa fermentation in Malaysia

In Malaysia, pulp preconditioning by post-harvest storage of cocoa pods leads to the reduction of nib acidification during subsequent fermentation, reduction of the acid note and an increase in cocoa flavour in the resulting raw cocoa. Data from several shallow-box fermentations, with material from unstored and stored pods, are compared and interpreted, obtained in the years 1984 to 1987 in a cooperational investigation of the Malaysian Agricultural Research and Development Institute (MARDI), Malaysia, and the Botanical Institute, Technical University of Braunschweig (TUBS), FRG. Prior to and during fermentation, pulp volume and pulp sugars; pH value, acetic acid and lactic acid content in the pulp and nibs; and oxygen concentration and temperature in the mass were determined. Some flavour assessments from selected samples are given. The great reduction in pulp volume per seed rather than the decrease of pulp sugars per seed during pod storage was found to be of the most importance. Pulp-volume reduction enhances mass aeration and increases the ratio of respiration to ethanol fermentation and its subsequent oxidation to acetic acid. As a consequence, the acidification of the seeds during the formative stages of flavour precursors (after the death of the seeds) is strongly reduced. With effectively dry stored pods (pulp volume per gram of seed ≤0·6 ml) the anaerobic phase during the initial stages of fermentation which is common with unstored pods is suppressed. Under these conditions the nib pH value does not fall below 5·0 and no drastic acid (and flavour) degradation at the end of fermentation is necessary to reduce the acidity in the seeds.     

乌桕脂真空结晶制取类可可脂及晶型初步研究

研究用乌桕脂制取类可可脂的新方法和产品的物理化学性能及其初步晶型结构。结果表明 :精炼乌桕脂在真空条件下于 3 7℃保温 2 3h制取的类可可脂产率为 70 %以上 ,且晶型大 ,易分离 ;调温后类可可脂结晶细腻 ,白色无异味 ,口感良好 ,质硬而脆 ,熔点 3 8℃ ,SFC值 2 0℃ ,89 4 % ;3 0℃ ,65 3 2 % ;3 7℃ ,4 62 % ;4 0℃ ,0 4 3 %。X 射线衍射和显微照相表明 :常温 2 5℃ ,结晶 2h ,形成假 β′晶型 ,3 0℃结晶 1d ,5℃结晶 1 6周为 β和 β′混晶     

Acoustically assisted supercritical CO2 extraction of cocoa butter: Effects on kinetics and quality

The effect of high power ultrasound (US) application and pressure on the supercritical fluid extraction (SFE) kinetics of cocoa butter and on characteristics of the extracted cocoa butter (fatty acids composition, transition temperatures, polyphenol content and antioxidant activity) has been evaluated. Extraction experiments were carried out at 40 °C and at two pressure levels of 400 bar and 550 bar, without and with US application of 50 ± 5 W, the extraction yield being significantly improved as the pressure increased and the ultrasound was applied. A Weibull model allowed the accurate simulation of the extraction curves, considering a constant shape factor α which was affected only by the US application, whilst the rate constant β was affected by both pressure and US application. In general, for all cocoa butter samples, the transition temperatures observed corresponded to the polymorph α, T_c = 9.9 ± 0.3 °C and T_m = 20.2 ± 0.4 °C. With regard to the fatty acid composition, the stearic (37.8 ± 0.8%), oleic (33.7 ± 0.2%), and palmitic (26.0 ± 0.6%) were the major acids, and none were found to be influenced by either pressure or ultrasound application. Similarly, the total polyphenol content and antioxidant activity were not affected by extraction conditions. The microstructure of cocoa beans after processing was affected by pressure and also by ultrasound application which promoted a breaking of the cell arrangement, facilitating the butter extraction.     

Lipids of oleaginous yeasts. Part II: Technology and potential applications

The process of lipid accumulation in the oleaginous yeasts cultivated in various fermentation configurations when either sugars and related compounds or hydrophobic substances are used as substrates is presented and kinetic models describing both de novo and ex novo lipid accumulation are analyzed. Technological aspects related with single cell oil (SCO) produced by oleaginous yeasts are depicted. The influence of culture parameters upon lipid production process is presented. Lipid production has been studied in batch, fed‐batch, and continuous cultivation systems using yeasts belonging to the species Lipomyces starkeyi, Rhodosporidium toruloides, Apiotrichum curvatum, Candida curvata, Cryptococcus curvatus, Trichosporon fermentans, and Yarrowia lipolytica. The potentiality of yeasts to produce SCO as starting material of 2nd generation biodiesel is indicated and discussed. Of significant importance is also the utilization of yeast lipids as substitutes of high added value exotic fats (e.g., cocoa butter). Lipid produced by the various yeasts presents, in general, similar composition with that of common vegetable oils being composed of unsaturated fatty acids, whereas cocoa butter is principally composed of saturated fatty acids, consequently the various strategies that are followed in order to increase the cellular saturated fatty acid content of the yeast lipid are presented and comprehensively discussed.     

Process simulation and debottlenecking for an industrial cocoa manufacturing process

Cocoa is a common ingredient for various food and confectionery products. Industrial production of this ingredient however is normally not optimised, due to the lack of appropriate analytical tools. Furthermore, cocoa processing is normally operated in semi-continuous mode, and this adds to the difficulty in optimising the various unit operations involved. In this work, a computer-aided process simulation tool was used to model and debottleckneck an industrial cocoa manufacturing process, with the aim to identify an economically viable production scheme that would double the current production rate.     

Cocoa-rich diet prevents azoxymethane-induced colonic preneoplastic lesions in rats by restraining oxidative stress and cell proliferation and inducing apoptosis

Cocoa is a rich source of bioactive compounds with potential chemopreventive ability but up to date its effectiveness in animal models of colon carcinogenesis has not been addressed. Herein, we investigated the in vivo effect of a cocoa-rich diet in the prevention of azoxymethane (AOM)-induced colon cancer and the mechanisms involved. Our results showed that cocoa feeding significantly reduced AOM-induced colonic aberrant crypt foci formation and crypt multiplicity. Oxidative imbalance in colon tissues seems to be prevented by cocoa as indicated by reduced oxidation markers levels and increased enzymatic and non-enzymatic endogenous defences. Cocoa-rich diet also exhibited antiproliferative effects by decreasing the levels of extracellular regulated kinases, protein kinase B and cyclin D1 together with pro-apoptotic effects evidenced by reduced Bcl-x(L) levels and increased Bax levels and caspase-3 activity. Our findings provide the first in vivo evidence that a cocoa-rich diet may inhibit the early stage of colon carcinogenesis probably by preventing oxidative stress and cell proliferation and by inducing apoptosis.     

Effect of pre-crystallization process and solid particle addition on microstructure in chocolate model systems

The microstructure of chocolate model systems was investigated at the meso (~ 10 ??m), micro (~ 50 ??m), and macro (0.1-1 mm) scales simultaneously, to examine effect of pre-crystallization process and/or solid particle addition on the formation of a dense structure. The structure density was quantified by measuring the diffusion rate of small molecules at different length scales. At the meso scale, fluorescence recovery after photobleaching (FRAP) was utilized to quantify local diffusion rate solely in the fat phase, whereas high-performance liquid chromatography (HPLC) measurements were made to assess the global diffusion of the same molecules at the macro scale. Both techniques were used in combination with microstructure characterization using confocal laser scanning microscopy (micro scale) and supported by differential scanning calorimeter melting curves for estimating cocoa butter polymorphism. Both FRAP and HPLC analysis generated relevant information on the effect of pre-crystallization and solid particle addition on the structure density. FRAP measurements gave detailed information on microstructure heterogeneity or homogeneity in the cocoa butter, whereas HPLC clearly revealed the impact of solid particles on the structure density. Combining the two techniques revealed that a compact and homogeneous structure obtained through optimized pre-crystallization is required at all times, i.e., immediately after cooling and throughout the product's shelf life, to retard global diffusion in confectionery systems.     

乌柏脂分提类可可脂工艺能耗的探讨(Ⅱ)

在乌桕脂分提制取类可可脂工艺中,使用真空冷却法与传统的冷却法相比有很多工艺上的优越性,为应用这种新工艺于工业生产,本文从工程热力学的角度对其能量经济性作比较深入的分析。