EFFECTS OF VISCOSITY OF LIQUID FOODS ON PALATAL PRESSURE

The deglutition of non-Newtonian liquids introduced into the mouth was studied dynamically by measuring palatal pressure (P) with pressure transducers set at three locations on the palate. The value of P and the swallowing pressure (S) changed only from 100 to 200 g/cm² over the viscosity range 10⁻² to 10¹ Pa.s. The retaining time (T) and work (W), required for swallowing after the liquid entered the mouth, remained almost constant up to a critical value of 1.0 Pa.s. above which both T and W increased markedly. When the viscosity was low, all of the liquid was swallowed in one deglutition, up to 15 mL volume. Therefore, T was almost constant but S increased with the volume. When the viscosity was high, the liquid was swallowed in several smaller portions. When the volume was high, T increased and S was either constant or it decreased.     

Denaturation of Bovine Serum Albumin (BSA) and Ovalbumin by High Pressure, Heat and Chemicals

Both native and denatured protein samples were examined by determining fluorescence and specific rotation, and by polyacrylamide gel electrophoresis (PAGE) and differential scanning calorimetry (DSC). Denaturation of ovalbumin by pressure was much less than by heat or by the chemical denaturants. Ovalbumin was denatured under high pressure, as confirmed by the decrease in its a-helical content to 72% and DSC endothermic enthalpy to 61%, but it showed no change in the PAGE pattern. With bovine serum albumin decrease in fluorescence was observed after denaturation by chemicals, but it did not change under high pressure.     

EFFECTS OF DIMENSIONS OF AGAR AND GELATIN GELS ON PALATAL PRESSURE PATTERNS

Eating of agar and gelatin gels in the mouth was studied dynamically in detail. The palatal presures on agar and gelatin gels of various concentrations and dimensions were detected by pressure transducers installed at three locations of the palate. For each of the gels, Pm (the maximum palatal pressure at the initial stage of mastication), P (the mean palatal pressure), W (work), and T (retaining time in the mouth) changed significantly when their concentrations increased. Moreover, gel dimensions also affected Pm, P and W. For a bite-size gel, Pm, P and W increased or remained constant, while for a finer sized gel, Pm, P and W were nearly constant regardless of the increase in rupture strength or gel concentration.     

Quality Improvement and Evaluation of Hypoallergenic Rice Grains

The color of hypoallergenic rice grains, produced by an enzymatic process was improved by treatment with diluted hydrochloric acid and washing with water. The acid-treated grains were steamed at the surface layer to prevent breakage. Textural evaluation showed the cooked hypoallergenic rice grains had a favorable stickiness/hardness ratio.     

MODULATING THE CONDITIONING OF MEAT BY THE USE OF ORYZACYSTATIN, A CYSTEINE PROTEINASE INHIBITOR OF RICE SEED ORIGIN

A new process was developed to regulate the papain-induced overtenderization of meat by using oryzacystatin, a cysteine proteinase inhibitor of rice seed origin. Meat cubes (2 × 2 × 2 cm each), aged 3 days, were treated with a 0.1 fold weight of papain solution and incubated at 8°C. The most favorable degree of tenderization resulted when a 2% papain solution was used for 2 h at 8°C. When the incubation was made for 24 h or longer, overtenderization resulted. The incubation of a meat cube with papain for the first 2 h and then with an adequate amount of added oryzacystatin for the subsequent 22 h was effective in regulating overtenderization. It was also confirmed by SDS-polyacrylamide gel electro-phoresis that the use of oryzacystatin under similar incubation conditions regulated the papain-aided hydrolysis of myofibrillar proteins.     

Production of Hypoallergenic Rice by Enzymatic Decomposition of Constituent Proteins

A method is proposed to produce hypoallergenic rice usable for patients with rice allergy. Newly harvested rice grains were dipped in carbonate (pH 9) containing glycerin monooleate and Actinase and then the mixture was exposed to a reduced pressure for degassing. The degassed mixture was incubated at 37°C for 24 hr to hydrolyze proteins. The process produced rice grains from which the major allergenic globulin was decomposed. The product was evaluated by the radioallergosorbent test (RAST), with the result that its RAST value suggested negative allergenicity in most cases. The product was clinically administered to 7 patients with atopic dermatitis and no allergic reaction was observed in 6 of the 7.     

INTERNATIONAL COOPERATIVE COMPARISON OF INSTRUMENT METHODS FOR COOKED RICE TEXTURE

The texture of 10 milled rices cooked by a standardized method in excess water was measured in 11 laboratories using various instrument methods that had been developed specifically for national samples. The samples selected represented a wide range of rice textures. Instrument indexes for hardness and stickiness of cooked rice generally were more sensitive than the corresponding taste panel scores in discriminating among the 10 cooked rice samples. Instrument indexes for hardness correlated positively among each other as did those for stickiness. Most hardness indexes showed significant negative correlation with stickiness indexes. Most hardness indexes were positively correlated with amylose content whereas stickiness indexes were negatively correlated with amylose content. The continued use of amylose content as an index of eating quality in a rice breeding program is justified.     

INHIBITING THE ACTIVITY OF ACTINIDIN BY ORYZACYSTATIN FOR THE APPLICATION OF FRESH KIWIFRUIT TO GELATIN-BASED FOODS

Fresh kiwifruit has potent proteinase activity that can be ascribed to actinidin, a cysteine proteinase. Without regulating this activity, kiwifruit can not be used satisfactorily as a food ingredient for protein-based foods. We found that oryzacystatin, a rice seed cysteine proteinase inhibitor, stoichiometrically inhibits the actinidin activity and can be used in making gelatin jellies with fresh kiwifruit slices. We also found that a gelatin solution mixed with an actinidin preparation did not form a gel because 118 kd and 130 kd components in the gelatin had undergone degradation. However, gelation occurred with no appreciable degradation in these two major gelatin components when oryzacystatin was added to this actinidin preparation.