Immortalization and Characterization of Rat Lingual Keratinocytes in a High-Calcium and Feeder-Free Culture System Using ROCK Inhibitor Y-27632.

Cultured keratinocytes are desirable models for biological and medical studies. However, primary keratinocytes are difficult to maintain, and there has been little research on lingual keratinocyte culture. Here, we investigated the effect of Y-27632, a Rho kinase (ROCK) inhibitor, on the immortalization and characterization of cultured rat lingual keratinocyte (RLKs). Three Y-27632-supplemented media were screened for the cultivation of RLKs isolated from Sprague-Dawley rats. Phalloidin staining and TUNEL assay were applied to visualize cytoskeleton dynamics and cell apoptosis following Y-27632 removal. Label-free proteomics, RT-PCR, calcium imaging, and cytogenetic studies were conducted to characterize the cultured cells. Results showed that RLKs could be conditionally immortalized in a high-calcium medium in the absence of feeder cells, although they did not exhibit normal karyotypes. The removal of Y-27632 from the culture medium led to reversible cytoskeletal reorganization and nuclear enlargement without triggering apoptosis, and a total of 239 differentially expressed proteins were identified by proteomic analysis. Notably, RLKs derived from the non-taste epithelium expressed some molecular markers characteristic of taste bud cells, yet calcium imaging revealed that they rarely responded to tastants. Collectively, we established a high-calcium and feeder-free culture method for the long-term maintenance of RLKs. Our results shed some new light on the immortalization and differentiation of lingual keratinocytes.

Exploring core functional microbiota related with flavor compounds involved in the fermentation of a natural fermented plain sufu (Chinese fermented soybean curd).

This study aimed to explore the core functional microbiotas related to flavor compounds involving in a naturally fermented soybean curd (plain sufu). Properties such as physicochemical parameters, flavor compounds (17 free amino acids, 21 fatty acids, and 14 aroma volatiles) and microbiota profiles were investigated, and their correlations were explored at 8 stages during production. Results from principal component analysis, multiple factor analysis, and partial least squares-discrimination analysis showed that these properties varied significantly in the eight stages. Furthermore, based on Pearson correlation coefficients and Variable importance for predictive components values between the microbiota profiles and flavor compounds, nine bacterial (Bacillus, Enterobacter, Lactobacillus, Sphingobacterium, Stenotrophomonas, Tetragenococcus, Trabulsiella, Unclassified, and Weissella) and six fungal (Alternaria, Sterigmatomyces, Actinomucor, Fusarium, Debaryomyces, Candida) genera were identified as core functional microbiotas significantly affecting the production of flavor compounds during the natural production. Overall, this study provided a comprehensive description of the dynamic changes of physicochemical parameters, flavor compounds, and microbiota profiles throughout the natural production of plain sufu. The similarities and variations among different stages, as well as correlation between flavor compounds and microbiotas would help to understand the mechanism of plain sufu production, and further to enhance the quality control of plain sufu.

Comparison between quantitative descriptive analysis and flash profile in profiling the sensory properties of commercial red sufu (Chinese fermented soybean curd).

BACKGROUND: Red sufu is a type of sufu produced by solid-state fermentation of soybean curd and coloration with red mold rice. The purposes of this study were: (i) to characterize commercial red sufu samples using the quantitative descriptive analysis (QDA) and flash profile (FP) by ten trained and ten untrained panelists, respectively; (ii) to compare the differences in panel performance, descriptive abilities and sensory maps between the two methodologies; and (iii) to compare the efficiency between QDA and FP using red sufu as the matrix. Techniques in multivariate analysis were utilized to explore the data. RESULTS: Results from generalized procrustes analysis (GPA) showed that panel performance by QDA was more repeatable and reached higher homogeneity than that by FP. Despite the confidence ellipse results of the 12 red sufus being better discriminated by QDA, the RV coefficient was high (RV = 0.852) between the configurations of the two-dimensional model (F1 and F2) of the two methodologies, indicating that the two methods are similar and closely related. Overall, QDA provided more accurate and detailed information, while FP provided a similar sensory map on product location and descriptive results. CONCLUSION: The FP technique appeared to be an efficient alternative approach to quickly evaluate sensory properties, including appearance, flavor, aroma and textural properties of an array of red sufu products. © 2018 Society of Chemical Industry.

Physiochemical characteristics and sensory properties of plant protein isolates-konjac glucomannan compound gels.

In this study, the effects of konjac glucomannan (KGM) at different concentrations on the physiochemical and sensory properties of soy protein isolate (SPI), pea protein isolate (PPI), or peanut protein isolate (PNPI) compound gels were investigated. The results revealed that when the ratio of PNPI to KGM was 90:10, the denaturation temperature of PNPI could be significantly enhanced to 119.32°C by KGM modification. Concerning the textural and microstructural features, the amount of KGM addition had positive correlation with the hardness and chewiness of each compound gel, however, too much KGM addition will cause the unstable internal structure of the PNPI/KGM compound gels (70:30 and 60:40). Furthermore, sensory results indicated that PNPI/KGM (80:20), PPI/KGM (80:20), SPI/KGM (80:20) had great potential to be considered as prototypes for novel plant-based products, which generated the highest acceptance scores of 5.04, 5.94, and 5.36 in each group, respectively.

Comparison of Pivot Profile (PP), Rate-All-That-Apply (RATA), and Pivot-CATA for the sensory profiling of commercial Chinese tea products.

Rapid sensory profiling methods relying on consumers' perceptions are getting prevalent and broadly utilized by labs and companies to supersede conventional sensory profiling methodologies. Till now, various intensity-based sensory methods such as the newly proposed Pivot-Check-All-That-Apply (CATA) are limitedly developed and compared. In this investigation, Pivot Profile (PP), Rate-All-That-Apply (RATA), and Pivot-CATA methods were applied and validated using tea consumers and commercial Chinese tea products as samples. Data from three approaches were collected, analyzed by correspondence analysis (CA), and used to compare the three methods assessing the panel assessment process, sensory maps, confidence ellipses, and practical applications. Pivot-CATA exhibited a high similarity with RATA (RV = 0.873), and a lower similarity with PP (RV = 0.629). Of the three intensity-related methods, confidence ellipses on the RATA sensory map were the smallest and overlapped the least. However, Pivot-CATA consumed less time in collecting data and its questionnaire was more friendly to participants compared with PP and made the difference in intensity of samples more noticeable to the participants than RATA due to the existence of the pivot sample. Its experimental versatility also allows for a wide range of applications, indicating that the Pivot-CATA is an approach with great promise for routine use.

Dynamic correlations between major enzymatic activities, physicochemical properties and targeted volatile compounds in naturally fermented plain sufu during production.

Dynamic changes and correlations between physicochemical properties, 14 targeted volatile compounds (TVCs) and six groups of enzyme activities during eight production stages of naturally fermented plain sufu were explored. Multiple factor analysis was used to discriminate between and group the samples into three clusters: cluster I comprised tofu and pehtze; cluster II comprised dried pehtze and salted pehtze; cluster III involved the aging stages. Clusters I and II were characterised by higher enzyme activities, while cluster III was characterised by the presence of diverse TVCs. Protease and esterase were strongly correlated with most of the TVCs. Esterase, in particular, contributed to the formation of three high molecular weight esters, namely, ethyl dodecanoate, ethyl (Z)-9-octadecenoate and ethyl (Z, Z)-9,12-octadecadienoate. The enzymes found contributed to the texture and flavour of naturally fermented sufu and will provide a good guide and control for using the enzymes directly to ripen sufu products.

Textural properties and consumer preference of functional milk puddings fortified with apricot kernel extracts.

Both the demand for functional foods and their consumption have increased rapidly in recent years. Apricot kernels, originated in China, are rich in dietary protein, fat, fiber, and exhibit high antimicrobial and antioxidant activities. The effects of the agar-gelatin ratio and milk volume on the texture of apricot kernel milk puddings were evaluated. Texture profile analysis indicated that increasing volumes of agar and milk contributed to the hardness and gumminess but reduced the cohesiveness of puddings. The pudding sample S2 (250 ml of milk, 200 ml of water, 60 g of raw apricot kernels, 30 g of sugar, 5 g of gelatin, and 2 g of agar) was ultimately determined as the essential texture matrix prototype for further development of puddings. The effects of the ratio of raw apricot kernels to roasted apricot kernels and cream content in puddings on consumer preference were determined by quantitative descriptive analysis and consumer testing. Both quantitative descriptive analysis and external preference mapping of all puddings (12 samples) indicated that the pudding sample P6 (250 ml of milk, 200 ml of water, 40 g of raw apricot kernels, 20 g of roasted apricot kernels, 40 g of cream, 30 g of sugar, 5 g of gelatin, and 2 g of agar) showed enhanced consumer acceptance. The properties driving preference for P6 were oral smoothness, overall flavor, degree of roast, and milky taste. P6 was ultimately selected as the prototype to incorporate apricot kernels for the development of functional milk puddings with fortified essential nutrients.

Multivariate relationships among sensory, physicochemical parameters, and targeted volatile compounds in commercial red sufus (Chinese fermented soybean curd): Comparison of QDA® and Flash Profile methods.

Selected physico- (texture and color) chemical (salt, protein, and moisture content) properties and 20 targeted volatile compounds (TVCs) from 12 commercial red sufus were investigated to identify correlations with sensory attributes obtained by either QDA or Flash Profile (FP). The intensities of 15 attributes from QDA and the ranking values of 19 attributes from FP of red sufus were evaluated, and a higher variance was generally found in the results from FP than those from QDA among the 12 samples. Principal component analysis (PCA) of TVCs showed that both the concentration and the ratio of volatile compounds influenced the flavor quality and the discrimination among the samples. Multiple factor analysis (MFA) was used to associate the sensory data from either FP or QDA with the physicochemical properties and TVCs of red sufus. The results showed that both FP and QDA data associated well with the physicochemical and TVC data, and the intensity of the sensory attributes could be predicted from the properties of red sufus. Pearson correlation coefficients between the sensory attributes (aroma/flavor) and TVCs pinpointed that a sulfur-like aroma was a key attribute in red sufus, and it might be a result of the comprehensive combination of different TVCs. The information reported here could be important for the quality control of traditional and new variants of red sufu products by providing an approach to substitute the sensory measurements with the instrumental measurements, and to strengthen the interpretation of sensory data by showing how they are affected by the physicochemical properties.

Effect of acid deamidation-alcalase hydrolysis induced modification on functional and bitter-masking properties of wheat gluten hydrolysates.

The low solubility of wheat gluten (WG) considerably limits its application. Owing to its high hydrolytic efficiency, alcalase was the protease selected for the enzymatic hydrolysis of WG. The functional properties of WG hydrolysate prepared by alcalase (AHWG) with a hydrolysis degree (DH) of 10% were better than those with DH 5% and DH 15%. The application of AHWG was hindered by its bitterness. To mask the bitterness of AHWG, WG was respectively deamidated with acetic acid, tartaric acid, and citric acid, followed by being hydrolyzed by alcalase to DH 10%. The citric acid deamidation-alcalase hydrolysis WG hydrolysate (CDAH) exhibited the best functional properties. Partial least squares regression analysis results indicated that CDAH exhibited an enhanced bitter-masking property attributable to a high content of umami taste amino acids (glutamic acid and aspartic acid). Thus, CDAH showed the greatest potential as a modified WG product to expand the application of WG.