Lactosucrose (O-β-D-galactopyranosyl-(1→4)-O-α-D-glucopyranosyl-(1→2)-β-D-fructofuranoside, LS), which is selectively utilized by Bifidobacteria in the human intestinal canal, was produced from sucrose and lactose by transfructosylation of β-fructofuranosidase from Arthrobacter sp. K-1. The optimum pH and temperature for LS production were pH 5.8-6.2 and 55-60°C respectively. The optimum ratio of lactose to sucrose and sugar concentration for LS production were 1 : 1 and 30-40%, respectively. The enzyme (750, 000 units) was incubated with a mixture of sucrose (100 kg) and lactose (100 kg) at pH 6 .0 at 55°C for 10 hr. From the reaction mixture, 60 kg of LS-98 (LS content 98%) was obtained by carbon column chromatography. The solubility of LS-98 is 367 g/100 ml H₂O (at 25°C) The sweetness of LS -98 is about 30% of that of sucrose. It is stable at neutral pH (pH 7. 0, 80°C, 2 hr), and fairly stable (decomposition % is less than 20%) at acidic pH (pH 3. 0, 80°C, 2 hr). It is stable at temperatures up to 120°C(pH 4. 5, 1 hr). The powder preparation is highly hygroscopic, and its solution shows higher activity of retaining moisture than sucrose. The water activity of LS-98 is 0.87 (25°C, Bx 70).

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A bacterium which produces a pullulanase was isolated from soil. A pullulanase (BSP) produced by the strain, Bacillus sectorramus, was purified by precipitation with ammonium sulfate and chromatographies on Phenyl-Sepharose CL-4B, DEAE-Sepharose CL-6B, γ-Cyclodextrin-Sepharose, and Toyopearl HW-55S. The purified enzyme was homogeneous in slab electrophoresis. The optimum pH and temperature of BSP were about 5.0 and 55°C, respectively. The molecular weight of BSP was estimated as 96, 000 and its isoelectric point was 4.7. The action pattern of this enzyme on pullulan was endo-wise. The final product from pullulan was maltotriose, not trimer which has a-l, 6 linkage in the molecular. By adding BSP, it was possible to significantly increase the glucose level in the standard condition of saccharification (pH 4.5, 60°C).

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A new carrier resin (FE-4611) was synthesized, on which α-amylase was immobilized. FE-4611 is a strongly hydrophilic resin of macroreticular type. α-Amylase was immobilized on FE-4611 and 3 species of Chitopearl. Continuous conversion of CDs into maltooligosaccharides with these kinds of immobilized a-amylase was investigated . The α-amylase immobilized on FE-4611 could keep up its effective performance over one month. This carrier resin bearing α-amylase was effectively rejuvenated for reuse by use of warm alkali solution . By contrast, α-amylase immobilized on Chitopearl lasted only for about two weeks . It was impossible to rejuvenate the enzyme immobilized on this carrier.

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A phytoglycogen from the endosperm of Italian millet and β-limit dextrin derived from the polysaccharide were hydrolyzed with a-amylase. A ratio of glucose, maltose and maltotriose to other oligosaccharides in the digests was calculated to be 0.12 (for β-limit dextrin) and 0.68 (for the phytoglycogen), respectively. From the values, the exterior chain was presumed, on the average, to be 4 to 5 times longer than the interior one.

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It was found that Pseudomonas saccharophila produced a maltotetraose-forming enzyme . The enzyme was purified by ammonium sulfate fractionation and column chromatography on DEAE-Toyopearl 650M and Toyopearl HW-55s. The activity recovery was 19% at the final step of the purification . The purified enzyme was homogeneous electrophoretically and its molecular weight was 62, 000. The optimum pH and temperature were 6.7 and 55°C, respectively. The enzyme was stable up to 40°C in the pH range of 5.5 to 10.5 for 1 hr, and thermostable in the presence of 2 mM CaCl₂, up to 45°C . The isoelectric point of the enzyme was 4.7. The enzyme activity was inhibited by metalions such as Ag⁺, Hg²⁺, Co²⁺, Cu²⁺, Fe³⁺, Al³⁺, Zn²⁺, and enhanced by Sr²⁺. The enzyme specifically produced maltotetraose from starch, did not act on glucose, maltose, maltotriose, and maltotetraose. The enzyme action proceeded from non-reducing ends of the substrates and seemed to be difficult skipping over the branches of amylopectin.

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In this paper, we report on the continuous conversion of maltose into glucose by use of the new carrier resin (FE-4611) on which glucoamylase was immobilized . FE-4611 is a strongly hydrophilic carrier resin of macroreticular type. The properties of the immobilized enzyme were examined and compared with those of native enzyme . The optimum pH for the immobilized enzyme shifted slightly to the acidic side compared with that of the native enzyme and the optimum temperature did not differ much from that of the native enzyme . K_m value of immobilized glucoamylase was 86.2 mM and that of native enzyme was 5.1 mM. The continuous conversion of maltose by the immobilized glucoamylase was stable and its half life was 68 days. The immobilized enzyme which had lost its activity was rejuvenated for its reuse.

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Binding of a substrate xylose to Streptomyces xylose isomerase (XIase) was observed by using a change (decrease) in fluorescence intensity (based on tryptophan residue) as a probe, and the binding parameters K_b and ΔF_max were evaluated for the xylose-XIase complex formation. An analogue xylitol was found not to produce the change in fluorescence intensity ; never theless, it competitively inhibits the XIase-catalyzed reaction for a substrate xylose . These findings suggest that the tryptophan residue (s) is located at the binding site of xylose to interact with some group of the xylose molecule, of which group is missing in xylitol . eq-Glucose, α-glucose and fructose were confirmed to be bound into XIase as a substrate, whereas IS-glucose was certified not to be a substrate of the enzyme.

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The amylase produced by a kind of fungus, Chalara paradoxa, is one of the raw starch digesting amylases. In this report, the studies on properties of this amylase and its application for ethanol fermentation were summarized. There were several glucoamylases (EC 3.2.1.3) in the culture filtrate, and each glucoamylase has a different isoelectric point. These glucoamylases were purified separately, and their general properties were studied. The kinetic studies showed that C. paradoxa glucoamylase has almost the same subsite structure as Rhizopus niveus. But C. paradoxa glucoamylase has rather high affinities for complex cyclodextrins. The raw corn starch granules digested by Ca paradoxa glucoamylase were studied with an electron microscope. The digested starch granules have a layered structure of less susceptibility to the amylase, and there were junctions among layers. In the raw starch digestion, the glucoamylase has cooperative action with the a-amylase (EC 3.2.1.1) which was purified from the culture filtrate. The ethanol fermentation of raw corn starch without cooking using C. paradoxa raw starch digesting amylase was performed. The ethanol yield was more than 90% at proper conditions.

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A review of" resistant starch."History, definition, and chemical, physical and physiological properties of the"resistant starch"are briefly reviewed.

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Chemically modified starches are widely used for Paper, Textile and Food Industries, etc. This paper explains the basic properties and uses of chemically modified starches .

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Remarks on various effects of the amino-carbonyl reactions in food and biological systems were made, especially on the studies of chemistry of brown pigment, browning reaction mechanism, Strecker degradation, oxygen effect, and inhibition of browning . Through these discussions, a very important role of a-dicarbonyl compounds, especially of low molecular ones, in the browning, flavor formation, protein denaturation, and others was emphasized.

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Melanoidin is a colored substance which is generally found in food system. Its formation mechanism has been mostly studied by model systems which consist of reducing sugar and amino acid. The author proposes a few methods to characterize melanoidin in food system. Electrofocusing profile of soy sauce melanoidin was found to be similar to that of the model melanoidin. Fe(‡U) chelating Sepharose 6B column chromatography of soy gave a proof of the presence of polyphenolic-type melanoidin which was adsorbed to the Fe (II) -column with strong affinity. Coffee melanoidin was adsorbed to the Cu (II) -column with stronger affinity than soy sauce melanoidin. Food melanoidins were categorized into 3 groups by microbial degradation using Coriolus versicolor. Model melanoidin, soy sauce and cane, molasses were characterized by reduction of color intensity by more than 50%; cocoa was characterized by adsorption of the melanoidin to the cell surface; coffee was almost stable against the microbial degradation.

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Flavor changes by heating foods are due to many reactions that occur among various components in foods. Among the reactions, the Maillard reaction of sugars with proteins (amino acids) significantly contributes to the flavor formation of heated foods. Simple Maillard model systems consisting of a sugar and an amino acid form varieties of flavors which are mainly changed by a class of an amino acid. The formation of flavors and volatile chemicals by the Maillard reaction is highly affected by reaction conditions : temperature, duration, water content and pH. The volatile compounds produced by the Maillard reaction include many classes of chemicals : furans, furanones, pyrones, Strecker aldehydes, pyrazines, pyrroles, oxazoles, thiols, thiophenes, thiazoles and cyclic polysulfides. The formation mechanisms of these compounds have been intensively investigated. The Maillard reactions are widely used to produce flavoring materials. These applications are shown in many patents claimed .

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Browning reaction causes a qualitative change of processed foods not only in color but also in taste, flavor, nutritive value etc. Therefore it is important to control the browning reaction in food processing. Control of browning reaction in several processed foods during processing and storage is discussed. They are as follows. (1) Repression of browning by decreasing of participating substances in amino carbonyl reactions. (2) Calculation of integrated browning degree by use of Arrhenius' equation and control of browning at the thermal process by the calculated browning degree. (3) Effect of temperature, oxygen and moisture on browning during storage.

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Aminocarbonyl reaction products show a strong antioxidative activity . By investigation on the relationship between the antioxidative activity and color intensity or nitrogen content of aminocarbonyl reaction products, it was indicated that the higher the color intensity or nitrogen content, the higher the antioxidative activity. The aminocarbonyl reaction products were fractionated into melanoidin and lower molecular reductones by gel filtration with Sephadex G-15. Strong antioxidative activity was found in the melanoidin fractions. Furthermore, this melanoidin was purified by gel filtration with Sephadex G-50 and 100 and then thin-layer chromatography. The antioxidative activities of these purified melanoidins were compared. Melanoidin B(M. W. ca . 4500) gave the best antioxidative activity, followed by melanoidin purified with Sephadex G-100, 50 and 15 in this order. However, the difference in these activities was not large . A comparison at the same level of weight showed that the melanoidin had almost the same antioxidative activity on linoleic acid as BHA. Furthermore, a synergistic effect was observed in combination of the melanoidin with BHA, BHT and natural tocopherol . Melanoidins were decolorized by ozone-oxidation and cultivation of Coriolus versicolor respectively . Both decolorized melanoidins showed the same antioxidative activity as that of the melanoidin .

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Heat-processed or cooked foods and fermented foods contain Maillard reaction products. Major reaction products are Amadori rearrangement compounds, dicarbonyls such as 3-deoxyglucosulose, furans such as 5-hydroxymethyl-furfural, pyrroles such as N-substituted pyrrole-2-carbaldehyde, and melanoidins which are polymerized brown substances. Some of the low molecular products are weakly mutagenic and melanoidins inhibit the activity of digestive enzymes such as amylases and proteases. Maillard-modified proteins also show antinutritive effects. On the other hand, melanoidins, which have antioxidative activity, in addition to the physiological effects similar to dietary fibers, show strong desmutagenic activity especially against mutagenic heterocyclic amines, inhibit the formation of nitrosoamines, and further, scavenge reactive oxygens such as H202 and OZ These effects by melanoidins suggest that they are anticarcinogenic. Therefore, it is important that both useful and adverse effects of the Maillard reaction products contained in foods are critically evaluated.

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