In recent years, the demand for beverages with lower caffeine concentrations has been expanding. However, traditional decaffeination technologies for tea and coffee not only remove caffeine, but also reduce the active components responsible for beverage flavor and quality. In this study, we investigated the selectivity and versatility of decaffeination by montmorillonite (MMT) in beverages. MMT adsorbed caffeine from tea and coffee extracts more selectively than activated carbon (AC). Optimization of the contact conditions enabled stable decaffeination and prevented elution of Fe ions from MMT, which causes discoloration of tea beverages. MMT exhibited similar caffeine adsorption properties with various types of tea extracts and coffee extracts. In addition, ion-exchanged MMTs, which also removed caffeine, improved the appearance quality of decaffeinated beverages. Overall, our findings suggest that MMT is a useful adsorbent for producing high-quality decaffeinated beverages. Specifically, decaffeinated tea beverages treated with MMT have been commercially available since 2014 from Kirin Beverage Company Ltd.

Kanroni, a highly popular Japanese food made with chestnuts, is prepared by stewing chestnuts in syrup. The Japanese chestnut (Castanea crenata Sieb. et Zucc.) ‘Porotan’ has excellent peelability and the frozen fruit is easily cracked by heating. In this study, we examined the effect of different ‘Porotan’ storage conditions on the quality of the prepared kanroni. Six chestnut processing strategies were tested: (i) immediate use after purchase (Cont), (ii) refrigeration (R), (iii) freezing (F), (iv) refrigeration for 1 month followed by freezing (RF), (v) refrigeration for 1 month followed by peeling and freezing (RPF), or (vi) freezing of RPF under vacuum packaging (RPF-V). For strategies (ii)-(iv), the chestnuts were peeled after storage. The most suitable strategies to prevent fruit cracking were R, RPF, and RPF-V. Kanroni prepared using frozen fruit (F, RF, RPF, or RPF-V) exhibited lower maximum stress and brittleness than when prepared using fruit from the Cont and R groups, indicating that frozen fruit would yield less firm kanroni. Furthermore, ‘Porotan’ storage conditions had only a slight effect on the color of the prepared kanroni. Notably, fruits processed by RPF-V showed higher maximum stress than those processed by RPF. These results indicate that RPF and RPF-V are the most suitable ‘Porotan’ storage conditions for the prepared kanroni.

The Japanese chestnut (Castanea crenata Sieb. et Zucc.) ‘Porotan’ has excellent peelability, but deteriorates due to cracking during heat-processing. The purpose of this study was to develop a kanroni (sweet-boiled) manufacturing method for frozen fruit resulting in minimal cracking of the fruit. Therefore, the effects of different kanroni manufacturing conditions (e.g., peeling and thawing methods, alum immersion time, heating temperature and the use of a lid placed deep inside the pot) on the rate of fruit cracking were studied. To further optimize the kanroni method, the effect of manufacturing conditions on color and physical properties was also studied. The best method with the lowest fruit cracking rate involved removal of the peel of the fruit through a boiling process, immersion in alum for 10 min or longer, and then boiling in hot water and sugar at 85°C. The methods having the greatest effect on maximum stress were the peeling and thawing methods, alum immersion time, and heating temperature; while color was affected the most by peeling and thawing methods, and alum immersion time. We concluded that fruit peeling via a boiling process, immersion in alum for 10 min or longer, and then boiling in hot water and sugar at 85°Cis the optimal manufacturing method for kanroni using frozen ‘Porotan’ chestnuts.

This study was carried out to evaluate the effect of differences in the textural hardness of chewing gum (hard vs soft chewing gum) on mastication. The hard chewing gum significantly increased the volume of saliva stimulated (p<0.05) compared to the soft chewing gum. Total bacterial counts in the saliva decreased significantly between before and after chewing of the hard chewing gum (p<0.05). The reduction rate of total bacterial counts in the saliva differed significantly between the hard and soft chewing gums (p<0.05). Moreover, brain activity in the pre-frontal area increased significantly between before and after chewing of the hard chewing gum during cognitive assignment examination (p<0.05). The hard chewing gum was observed to increase the volume of saliva stimulated, decrease total bacterial counts in the saliva, and increase brain activity in the pre-frontal area during cognitive assignment examination compared to the soft chewing gum. The hard chewing gum was suggested to be effective for mastication as well as contribute to oral hygiene.

Rice flour bread made without wheat gluten leads to an increased consumption of rice and can be eaten by people with wheat allergies. However, because gluten-free rice flour bread shows low swelling and poor texture, a new processing technology (rice-gel) was proposed as a substitute for wheat gluten. This study used rice flour and rice-gel to make bread, and focused on the amount of water added to the dough. Bread properties were evaluated by examining hardness and its rate of change, specific volume and cross-sectional images. Rice-gels were made from white rice or brown rice and a comparison of their properties was conducted.

The thermal behaviors of pore water were studied by adiabatic calorimetry between 50 and 300K. We utilized pore water in 1) silica MCM-41 with pore diameters of 1.5 to 5.0nm, 2) sephadex G10 of a cross-linked dextran gel, and 3) bovine serum albumin (BSA) of a globular protein. The three pore walls differed in hydrophilic/hydrophobic properties, pore size and shape, and flexibility. The hydration levels for G10 and BSA were h=0.273 and 0.321, as evaluated by the mass ratio of water to anhydride. Pore water in MCM-41 revealed glass transitions at around 115, 165, and 210K; the first was attributed to the freezing-in of interfacial water molecules neighboring the pore walls. The temperatures, which increased discretely with pore size, were interpreted to correspond, respectively, with the situations where 2, 3 and 4 hydrogen bonds are broken simultaneously in the activation for rearrangement of water molecule. The glass transitions in hydrated G10 and BSA displayed some similar behaviors as those in MCM-41. It was found that the number of accessible microscopic states of pore water in G10 was small with regard to the configurational degree of freedom below 273K, as compared with those of bulk water and pore water in MCM-41. The number of pore water in BSA was further small, even at 300K, suggesting that the structure of BSA with h=0.321 is determined by BSA itself and most water molecules are confined to narrow spaces.

Spores are a highly resistant form of bacteria and are capable of surviving various environmental stresses. When food is contaminated with spores, it can result in food spoilage and food-borne illness. Although it is important to develop procedures to control the germination and outgrowth of food-contaminating spores, there is limited biological information about the spores of anaerobic Clostridium spp. In this mini-review, recent advances in the biological behaviors of Clostridium spp. spores are summarized, and the possible burden in food hygiene induced by putative “damaged-but-viable” spores is discussed. Concerted efforts to elucidate the biological specificity of spores are needed to develop new control measures applicable to a variety of hygienic processes.

The control of microorganisms is one of the most important issues in food preservation. Water activity, temperature, pH and preservatives are all critical factors that affect microbial growth. The application of acid stress (low pH and weak acid preservatives) is widely used to inhibit bacterial growth, as it decreases the internal pH below the normal physiological range. In addition to low pH effects, acid preservatives compromise the functional integrity of the cell membrane, cell wall, metabolic enzymes, protein synthesis system and/or genetic material. Certain bacteria, such as Escherichia coli and Salmonella spp., are equipped with elegant systems that enable survival in acidic environments.

Food processing by high hydrostatic pressure (HHP) has several characteristic aspects, including homogeneous and almost spontaneous transmission of pressure; inactivation of viruses and microbes; suppressed deterioration of nutrients, flavors, and pigments; denaturation of food biopolymers such as proteins and starch; enhanced liquid impregnation and air bubble dissolution; and shucking of bivalves and crustaceans. Among these, microbial inactivation has been intensively studied for practical applications in processing agricultural produce with minimal quality loss and reduced risk of pathogenic and/or spoilage microbes, especially bacteria. HHP treatment, as well as other intervention technologies, may inactivate bacteria lethally and sublethally. However, sublethal inactivation of bacteria has not been elucidated sufficiently. This paper reviews bacterial inactivation by HHP with a focus on bacterial injury and recovery.