Anton Apriyantono

Microorganisms with a Taste for Vanilla: Microbial Ecology of Traditional Indonesian Vanilla Curing

ABSTRACT The microbial ecology of traditional postharvesting processing of vanilla beans (curing) was examined using a polyphasic approach consisting of conventional cultivation, substrate utilization-based and molecular identification of isolates, and cultivation-independent community profiling by 16S ribosomal DNA based PCR-denaturing gradient gel electrophoresis. At two different locations, a batch of curing beans was monitored. In both batches a major shift in microbial communities occurred after short-term scalding of the beans in hot water. Fungi and yeast disappeared, although regrowth of fungi occurred in one batch during a period in which process conditions were temporarily not optimal. Conventional plating showed that microbial communities consisting of thermophilic and thermotolerant bacilli (mainly closely related to Bacillus subtilis, B. licheniformis,, and B. smithii) developed under the high temperatures (up to 65°C) that were maintained for over a week after scalding. Only small changes in the communities of culturable bacteria occurred after this period. Molecular analysis revealed that a proportion of the microbial communities could not be cultured on conventional agar medium, especially during the high-temperature period. Large differences between both batches were observed in the numbers of microorganisms, in species composition, and in the enzymatic abilities of isolated bacteria. These large differences indicate that the effects of microbial activities on the development of vanilla flavor could be different for each batch of cured vanilla beans.

Comparison between traditional and industrial soy sauce (kecap) fermentation in Indonesia

Growth of lactic acid bacteria and amino acid production at an Indonesian soy sauce manufacturer, employing modern Japanese process technology, indicated that brine fermentation for one month is sufficient for industrial kecap production. Compared to traditional Indonesian soy sauce fermentation, application of modern Japanese process technology resulted in an obvious but not essential yeast fermentation.

Rate of browning reaction during preparation of coconut and palm sugar

Abstract The objective of this research was to analyse the rate of browning reaction during preparation of palm and coconut sugar. Brown colour formation during preparation of coconut sugar at a laboratory scale followed a zero order reaction with a constant of formation (k) equal to 5.15×10−3 AU min−1 (AU=Absorbance Unit). The amount of glucose, fructose and sucrose decreased during this preparation and the decrease followed a zero order reaction for glucose, first order for fructose, whereas that for sucrose followed neither zero nor first order reaction. After 90 min boiling (when the coconut sugar was formed), the amounts of glucose, fructose and sucrose left were 27.7%, 35.7% and 83.7% of the initial amount, respectively. The relative percentage area of furans and pyrazines increased during the preparation of coconut sugar and this increase followed a first order reaction for both. The palm sap with initial pH adjusted to 8.0 was heated in a closed system at temperatures of 105, 115 and 121 °C for up to 300 min and every 30 min, the brown colour of the sap was measured at 420 nm. The brown colour formation followed a zero order reaction with k equal to 0.87×10−3, 4.46×10−3, 6.58×10−3 AU min−1 for reaction temperatures of 105, 115 and 121 °C, respectively. The activation energy of the brown colour formation was 160.77 J mol−1. In a separate experiment, an aqueous solution containing glucose, fructose and sucrose at a concentration of 3.42%, 1.56% and 7.22%, respectively, with and without addition of 0.01% l -lysine, each was adjusted to pH 8.0 and heated at 121 °C and analysed as above. The rate of brown colour formation that resulted from heating model aqueous solution containing sugars and l -lysine resembled that resulting from heating palm sap. Therefore, the Maillard reaction plays an important role in the formation of brown colour during preparation of palm sugar.

Sensory and Peptides Characteristics of Soy Sauce Fractions Obtained by Ultrafiltration

Soy sauce is a light brown to black liquid having umami and delicious tastes with an appetizing aroma. The most known type of soy sauce is the salty soy sauce. This soy sauce can be grouped into two types, i.e., a Japanese type (only found in Japan) and a Chinese type (produced in China and South East Asia). The Japanese soy sauce uses soybean and wheat (ratio 1:1) as the main raw material, whereas the Chinese type uses no or very little wheat besides soybean (Roling, 1995). In Indonesia, traditional soy sauce producers usually use black soybean, but some use yellow soybean, whereas modern producer use a mixture of wheat and defatted soybean. The main preparation of this soy sauce involves mold and brine fermentation to afford moromi which is then filtered and pasteurized to give soy sauce.

Mobilization of primary metabolites and phenolics during natural fermentation in seeds of Pangium edule Reinw.

Abstract Fermented seeds of the tropical tree Pangium edule Reinw. are a speciality in Indonesia and have been used as spices. The fermentation process of the seeds is a natural spontaneous process, which occurs 40 days following seed maturity and treatment. This study reports some biochemical changes, especially primary metabolites, and antioxidant activity associated with mobilization of lipids and phenolics during seed fermentation. The lipid content increased slightly (46.07–50.95% db) although the dominant fatty acid composition did not change. The dominant fatty acids were oleic acid (C 18:1 n-9) and linoleic acid (C 18:2 n-6). During fermentation, the decrease in fatty acid content in lipid coincided with the increasing acid value, which indicated that free fatty acids increased in seeds during fermentation. The dominant tocol in the seed, γ-tocotrienol, increased (69.8–123.3 μg g −1 freeze-dried seed) during fermentation. In general, overall protein content and amino acid composition did not change but non-soluble protein increased while soluble protein decreased. The changes in carbohydrate fraction showed that total crude carbobydrate, neutral detergent fibre (NDF, as cellulose, hemicellulose, and lignin) decreased, but reducing sugar increased and starch content did not change. Enzyme assays showed that microorganisms may be involved in the fermentation process. β-glucosidase, an enzyme that can cleave glycosidic bonds of conjugated phenolics and guaiacol peroxidase (GPX) activities increased. The total phenolics content in seeds increased substantially corresponding to the increase in β-glucosidase but antioxidant activity of phenolic extracts did not change.