Optimization of extraction conditions of gelatin from buffalo (Bubalus bubalis) skins using response surface methodology

The present study was to determine optimum conditions for gelatin extraction from the skin of buffalo (Bubalus bubalis) using response surface methodology. A central composite design (CCD) was performed to evaluate the effects of NaOH concentration ( X 1 ), pre-treatment time ( X 2 ), extraction temperature ( X 3 ), and extraction time ( X 4 ) on the yield (Y ₁), gel strength (Y ₂), and hydroxyproline content (Y ₃) of the extracted gelatin. The optimal combination of the independent variables for a good gelatin yield with high gel strength and hydroxyproline content was found at X 1 (0.77 M), X 2 (5.08 h), X 3 (62.93 °C) and X 4 (11.62 h). The experimental values for Y ₁ (16.91%), Y ₂ (236.5 g), and Y ₃ (41.4 g/100 g) were in good agreement with the predicted values of 17.87% yield, 237.80 g gel strength and 41.90 g/100 g of hydroxyproline content. Extraction temperature and extraction time were observed to be the most important factors that influenced the yield, gel strength, and hydroxyproline content, meanwhile pre-treatment time showed negative correlations with the yield and hydroxyproline content of the extracted gelatin. This study demonstrated that manipulation of specific parameters could improve extraction efficiency without compromising the quality of buffalo gelatin, thereby promoting it as an alternative source for gelatin production.

Gas Permeability of Mold during Freezing Process Alters the Pore Distribution of Gelatin Sponge and Its Bone-Forming Ability

Freeze-drying, also known as lyophilization, is widely used in the preparation of porous biomaterials. Nevertheless, limited information is known regarding the effect of gas permeability on molds to obtain porous materials. We demonstrated that the different levels of gas permeability of molds remarkably altered the pore distribution of prepared gelatin sponges and distinct bone formation at critical-sized bone defects of the rat calvaria. Three types of molds were prepared: silicon tube (ST), which has high gas permeability; ST covered with polyvinylidene chloride (PVDC) film, which has low gas permeability, at the lateral side (STPL); and ST covered with PVDC at both the lateral and bottom sides (STPLB). The cross sections or curved surfaces of the sponges were evaluated using scanning electron microscopy and quantitative image analysis. The gelatin sponge prepared using ST mold demonstrated wider pore size and spatial distribution and larger average pore diameter (149.2 µm) compared with that prepared using STPL and STPLB. The sponges using ST demonstrated significantly poor bone formation and bone mineral density after 3 weeks. The results suggest that the gas permeability of molds critically alters the pore size and spatial pore distribution of prepared sponges during the freeze-drying process, which probably causes distinct bone formation.

Preparation of low-molecular-weight, collagen hydrolysates (peptides): Current progress, challenges, and future perspectives

Collagen hydrolysates (peptides) derived from food processing byproducts have been used to produce commercially valuable food ingredients due to their potential to trigger certain desirable physiological responses in the body. Low-molecular-weight (LMW) collagen hydrolysates are generally thought to exert better bioactivities than their larger counterparts. However, the preparation of LMW collagen hydrolysates is often impeded by their special structure, cross-linking, and hydroxyproline. This review briefly introduces the motivation of the food industry to prepare LMW collagen hydrolysate from food processing byproducts. We further summarize recent progress on the preparation of LMW collagen hydrolysates and methods to determine the molecular weight. We then discuss the challenges and then provide perspectives on future directions in preparing LMW collagen hydrolysates.