Jinhu Tian

Structural properties of films and rheology of film-forming solutions of chitosan gallate for food packaging.

The chitosan gallates (CG) were obtained by free-radical-initiated grafting of gallic acid (GA) onto chitosan (CS) in this work. The chemical structures of the CG were corroborated by UV-vis, GPC and (1)H NMR analysis. The grafting reaction was accompanied with a degradation of the CS molecule. The shear-thinning flow behavior of CG film-forming solutions (CG FFS) decreased with the grafting amount of GA into CS chain, while the CG FFS grafted at a lower GA value behaved like a networks containing entangled or cross-linked polymer chains with a more elastic behavior. The increasing of GA grafting onto the CS chain led to a reduction of tensile strength, elongation at break and water resistance in the corresponding films, but increases in the antioxidant and antimicrobial activities were observed. The microstructure of the film was investigated using scanning electron and atomic force microscope, and the results were closely related to the observed film properties.

Domestic cooking methods affect the phytochemical composition and antioxidant activity of purple-fleshed potatoes

The effects of domestic cooking methods (boiling, baking, steaming, microwaving, frying, and stir-frying) and a new cooking method (air-frying) on the composition of phytochemicals (phenolics, anthocyanins, and carotenoids) and the antioxidant activity in purple-fleshed potatoes were investigated. Compared with raw potatoes, reductions of 23.59-90.42%, 7.09-72.44%, 7.45-83.15%, and 20.15-76.16% in the vitamin C, total phenolic, anthocyanin and carotenoid contents, respectively, was observed after cooking. Decreases of 7.88%, 21.55%, 22.48, 6.31%, and 61.38% in DPPH radical-scavenging activity was also observed after boiling, steaming, baking, microwaving and stir-frying, respectively, whereas an increase of 30.52% was noted after air-frying. A correlation analysis revealed that the antioxidant activity was in accordance with the total phenolic content and that this activity showed the lowest correlation with the vitamin C content. Among all of the cooking methods investigated in this study, stir-frying retained only slight levels of the phytochemicals and antioxidant activity observed in raw potatoes, whereas steaming and microwaving were able to retain most of the health-promoting compounds found in raw potatoes and may thus be suitable methods for cooking potatoes.

Health benefits of the potato affected by domestic cooking: A review

Potato (Solanum tuberosum L) is an important food crop worldwide and a good source of vitamins, minerals and dietary fiber as well as phytochemicals, which benefits human body as nutrients supplementary and antioxidants. However, cooked potato is also considered as a high-glycemic-index food because of its high content of rapidly digestible starch, long-term consumption of which will increase the risk of cardiovascular disease and type-2 diabetes. Domestic cooking (boiling, frying, steaming, etc.) are usually adopted before potato consumption. The chemical, physical and enzyme modifications that occur during cooking will alter the potatos antioxidant capacity and digestibility, which subsequently affected on the bioavailability of phytochemicals and the postprandial glycemic response of the human body. We reviewed the recent publications on the effects of domestic cooking on the nutrition, phytochemicals and the glycemic index changes of the cooked potato. Furthermore, the possible mechanisms underlying these changes were discussed, and additional implications and future research goals were suggested.

Effects of preparation methods on potato microstructure and digestibility: An in vitro study.

The effects of preparation method (boiled, cooled, and reheated) on the structural characteristics and in vitro digestibility of potato were investigated. The highest equilibrium starch hydrolysis was obtained after boiling (82.21%), followed by reheating (66.98%) and cooling (54.31%). The potato after cooling treatment exhibited a narrower melting temperature range and a higher melting enthalpy compared with the potatoes after boiling and the microwave reheating. X-ray diffraction patterns revealed that the relative crystallinity of the cooled potato was higher than those of the reheated and boiled potatoes, consistent with the results in melting enthalpy. Moreover, compared with the boiled potato, a large number of wrinkles were observed on the surface of the cooled potato, whereas after microwave reheating, larger clearances of starch granule regions were found. This study demonstrated that cooling and microwave reheating significantly affected the potatos microstructure and digestibility and were suggested as alternative choices to prepare potato dishes.

Parboiling reduced the crystallinity and in vitro digestibility of non-waxy short grain rice

The impact of parboiling on starch digestibility of cooked rice was examined through an in vitro digestion model. Results indicated that the equilibrium starch hydrolysis of polished rice was the highest (86.55%), followed by that of parboiled-polished (83.94%), brown (80.59%) and parboiled rice (76.95%). X-ray diffraction analysis indicated that A-type crystals were predominant in brown rice and polished rice, while A-, B- and V-type crystalline structures coexisted in parboiled rice and parboiled-polished rice. Thin and compact layers were observed on the surfaces of parboiled rice and were considered to be physical barriers that reduce the starch digestibility. The study demonstrates that parboiling could change the crystallinity and reduce the starch digestion of rice significantly.

The microstructure of starchy food modulates its digestibility

ABSTRACT Starch is the main carbohydrate in human nutrition and shows a range of desired food properties. It has been demonstrated that fast digestion of starchy food can induce many health issues (e.g., hyperglycaemia, diabetes, etc.); therefore, how to modulate its digestion is an interesting topic. Previous studies have revealed that the microstructure and digestibility of starchy food of different botanical origin or from multiple processes are quite different; modulating starch digestion by retaining or altering its microstructure may be effective. In the present review, the current knowledge of the relationship between microstructural changes to starchy food and its digestibility at molecular, cell and tissue, and food processing levels is summarized. New technologies focused on microstructure studies and ways to manipulate food microstructure to modulate starch digestibility are also reviewed. In particular, some insights focusing on the future study of microstructure and the digestibility of starchy food are also suggested.

Effects of Chinese pickled and dried mustard on nutritional quality, sensory quality, and shelf life of steamed pork belly

Abstract Steamed pork with pickled and dried mustard (PDM) is a famous Chinese dish. Here, we examined the effects of PDM on nutritional quality, sensory quality, and shelf life of steamed pork belly. Proximate composition, lipid oxidation, fatty acid profiles, protein hydrolysis and oxidation, sensory evaluation, and induction period (IP) of steamed pork belly were determined after addition of different levels (0–100%, WPDM/W pork belly) of PDM. The results demonstrated that PDM could significantly (p < .05) enhance the loss of moisture and fat, increase the ratio of unsaturated to saturated fatty acids, and decrease lipid and protein oxidation in steamed pork belly. Additionally, IP values and steamed pork belly preservation times increased as the amount of added PDM increased. Best sensory quality was achieved when moderate levels of PDM (40%) were added to steamed pork belly. These findings provide insights into the beneficial effects of PDM on steamed pork belly.