Fanbin Kong

Disintegration of Solid Foods in Human Stomach

Knowledge of the disintegration of solid foods in human stomach is essential to assess the bioavailability of nutrients in the gastrointestinal (GI) tract. A comprehensive review of food gastric digestion, focusing on disintegration of solid foods, is presented. Most of the research reviewed in this paper is contained in the medical, pharmaceutical, food, and nutritional literature. Stomach physiology is briefly introduced, including composition and rheological properties of gastric contents, stomach wall motility in fed/fasted states, and hydrodynamic and mechanical forces that act on the ingested food. In vivo and in vitro methods used for studying food and drug digestion in GI are summarized. Stomach emptying rate, which controls the rate of absorption of nutrients, is highly related to the disintegration of foods. This topic is highlighted with focus on the important mechanisms and the influence of chemical and physical properties of foods. Future research in this area is identified to increase our fundamental understanding of the food digestion process in the stomach as related to the food composition, material properties such as texture and microstructure, and chemical characteristics. This information is necessary to develop new guidelines for seeking innovative processing methods to manufacture foods specifically targeted for health.

Changes of soybean quality during storage as related to soymilk and tofu making.

Soybeans are stored and transported under various humidity and temperature conditions. Soymilk and tofu are two of the most important foods made from whole soybeans. The objective of this study was to investigate the influence of storage conditions on soybean quality as related to soymilk and tofu-making properties. Soybeans of 3 different genotypes (Proto, IA2032, and Vinton 81) were stored in varying conditions: temperature ranging from 4 to 50 degrees C, relative humidity from 55% to 80%, initial moisture content from 6% to 14%, and storage time up to 15 mo depending upon storage conditions. The effects of different storage conditions on soybean color, solids and protein extractability, soymilk pH, tofu yield, tofu solids and protein contents, tofu color, and texture were investigated. While no significant changes occurred for the soybeans stored at 4 degrees C, the soybeans stored at high temperatures (30 to 50 degrees C) exhibited significant quality loss (P < 0.05). The degradation of soybean lightness (Hunter L), color difference (Delta E), and solid extractability exhibited a linear relationship with time. Soak weight decreased at high temperature and relative humidity, but increased at mild storage conditions. Several combinations of storage conditions at temperatures exceeding 30 degrees C produced a drastic loss in tofu yield. Storage also affected the tofu making process by reducing optimum mixing time to produce the highest tofu yield. Varietal difference in soybean storability was observed. The results provided useful information for the soybean processing industry to store soybeans using the optimal storage conditions and to estimate soybean quality after storage.

Kinetics of Food Quality Changes During Thermal Processing: a Review

Thermal treatments are extensively used in the food industry for control of pathogenic and spoilage microorganisms and spoilage enzymes. Food quality degradation during those treatments can be a major concern for consumer acceptance. Kinetic studies and mathematical models on quality changes of foods are essential in proper design of thermal treatments to ensure consumer satisfaction. This study provides a comprehensive review of recent progresses on quality kinetics for thermal treatments to inactivate microorganisms and enzymes in foods of both plant and animal origins. This paper mainly covers the theoretical basis for studying quality kinetics, common and special kinetic models to describe major quality attributes, such as appearance, texture, and nutrients, and potential applications of quality kinetic models to developing thermal treatment protocols. Finally, this review describes the challenges in quality kinetic studies and proposes recommendations for future research to maintain food quality and extend shelf life.

Cellulose nanofibers coated with silver nanoparticles as a SERS platform for detection of pesticides in apples

A nanocomposite based on cellulose nanofibers (CNFs) coated with silver nanoparticles (AgNPs) was developed in this study as a flexible and effective substrate for use in surface-enhanced Raman spectroscopy (SERS) analysis. An effective Raman indicator molecule, 4-aminothiophenol (pATP), was used to characterize AgNPs impregnated on CNFs. The CNF-AgNP films were used in SERS analysis to detect thiabendazole (TBZ) pesticides in apples. The influence of pH on the SERS spectra of TBZ was investigated because TBZ is a neutral molecule that has a low affinity for AgNPs. The pH of TBZ solution was decreased to below the TBZs pKa, thus enabling the electrostatic attraction between TBZ and AgNPs. CNFs can prevent the uncontrolled aggregation of AgNPs in low pH environment and serve as an effective AgNP/nanocellulose platform for SERS analysis. Results of this study demonstrate that CNF-AgNP nanocomposites can be used to rapidly detect TBZ pesticides in various food products.

Statistical and kinetic studies of the changes in soybean quality during storage as related to soymilk and tofu making.

The objective of this study was to develop statistical equations and kinetic models to describe the changes of soybean quality during storage. Significant correlations (P < 0.0001) were found among most of quality attributes including color parameters (Hunter L, a, b, and DeltaE), solid extractability (as expressed by soymilk solids content), soymilk pH and protein content, tofu yield, hardness, and protein content. Regressed linear equations were developed between color indices (L/L(0), DeltaE) and soymilk/tofu making properties. Empirical equations were developed to relate soybean color indices (L/L(0), DeltaE) and storage conditions including variables of initial moisture content (MC), relative humidity (RH), temperature (T), and duration (t). Kinetics of the changes in soybean color and extractability during storage at 70% RH and 22 to 40 degrees C were investigated. The kinetics was well described by zero-order kinetics. The Arrhenius equation adequately described the temperature dependence of the reaction rate constants for all parameters, from which the activation energies and rate constant were obtained. The equations developed in this study provided simple methods to monitor soybean quality and predict quality changes of soybeans during storage at various conditions.