Processing and Utilization of Grapefruit Peel Byproducts
Developing deep processing and utilization of grapefruit peel can reduce the waste of grapefruit peel, protect the environment, promote the added value of grapefruit industry, and provide reference for the development of new materials and nutritious foods in food industry.
Grapefruit peel dietary fiber can improve changes in obesity-related characteristics and intestinal microbial flora imbalance in mice fed a high-fat diet
Abstract
Grapefruit peel is rich in dietary fiber and multiple biological activities, but it is often discarded. This study evaluated the biological activity of grapefruit peel dietary fiber (PPDF) in preventing obesity and regulating intestinal flora in a high-fat diet (HFD)-induced obese mouse model. From the composition point of view, the prepared PPDF had a total dietary fiber content of 89.64%, an insoluble dietary fiber content of 53.27%, and a soluble dietary fiber content of 36.37%. PPDF treatment significantly reduced the body weight gain and fat accumulation in liver and epididymal tissues of obese mice; significantly alleviated HFD-induced dyslipidemia; restored triglyceride, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol levels to normal levels, and a 5% PPDF dose restored total cholesterol to normal levels. In addition, PPDF improved HFD-induced intestinal flora imbalance by increasing intestinal microbial diversity, reducing the ratio of Firmicutes/Bacteroidetes, increasing beneficial bacteria (Bifidobacterium, Heterobacteria and Lactobacillus), and reducing harmful bacteria (Staphylococcus and Corynebacterium_1). This indicates that PPDF can be used as a functional food for preventing obesity and alleviating dyslipidemia or as a potential probiotic for improving intestinal flora imbalance.
Conclusion
In this study, PPDF with a fiber content of about 90% was extracted from grapefruit peel waste. Adding PPDF to the diet for 6 weeks significantly reduced the weight gain, liver weight gain and outer membrane fat accumulation of obese mice, and restored the lipid indicators TG, LDLC, HDL-C and TC to normal levels in a dose-dependent manner. Supplementation of PPDF restored the HFD-induced decrease in intestinal microbial diversity and increase in F/B ratio, restored the abundance of key anti-obesity bacteria (such as Bacteroides, Bifidobacterium, Lactobacillus, etc.), and significantly inhibited the growth of bacteria associated with obesity and inflammation (Firmicutes, Staphylococcus, Corynebacterium-1, etc.). Therefore, PPDF alleviated HFD-induced weight gain and dyslipidemia in mice and reduced visceral fat accumulation. These positive benefits are related to the regulation of intestinal microbiota. PPDF has the potential to be developed into a functional food and prebiotic for preventing obesity, regulating blood lipids and intestinal flora.
Composite optimization and characterization of edible packaging film reinforced with nanocellulose from grapefruit peel residue
Abstract
Grapefruit processing waste is a potential source of high-quality dietary fiber, and the development of edible packaging film based on grapefruit peel residue dietary fiber has important technical and functional potential. In this study, an edible packaging film based on dietary fiber was successfully developed for the first time. The packaging film used grapefruit soluble dietary fiber (GSDF) in grapefruit peel pomace as substrate and nanocellulose (GNCC) as filler. The principal component analysis, membership function method and response surface method were used to determine the optimal process for preparing the edible packaging film, and the influence of GNCC on the material was analyzed. The results showed that the overall performance score of the edible packaging film with 1% GNCC was 0.764. The maximum pyrolysis temperature increased from 226.36 ℃ to 227.10 ℃, the melting temperature (Tm) increased by 5.54 ℃, and the crystallinity increased by 2.95%. The film solution has non-Newtonian and solid-like properties. The results show that the edible packaging film developed with grapefruit peel pomace and dietary fiber as raw materials has broad application prospects in the field of food packaging.
Conclusion
This study successfully combined GSDF with GIDF for the first time, and developed an edible packaging film with GSDF as the substrate and GNCC as the reinforcing material. The optimal preparation process of edible packaging film was determined by principal component analysis, membership function synthesis and response surface methodology. The effect of GNCC on edible packaging film was analyzed. The results showed that the edible packaging film components had good biocompatibility and no chemical reaction occurred; the edible packaging film with 1% GNCC had the highest overall performance score, more complete crystal structure and higher thermal stability; the shear thinning phenomenon of the film solution was more obvious, and the film solution did not meet the Cox-Merz rule. In summary, GSDF/SA/GNCC edible packaging film has opened up a new way for the high-value utilization of grapefruit peel waste and has broad application prospects in the food industry as an edible packaging material. The application of edible packaging film in various food systems needs to be further evaluated.
Grapefruit peel as an effective adsorbent for various gel matrices: the effect of particle size and powder concentration
Abstract
The study demonstrated a reliable method to upgrade plant waste into various gels as promising fat substitutes. Grapefruit peel (Citrus grandis L.; PP) was used to make a gel-like adsorbent similar to hydrogels and oleogels. PP was dried and ground into particles of 125, 250, and 500 μm. PP powder (10% to 40%) was mixed with oil or distilled water for 2 min without heating. Self-sustaining gels were formed from particles of 125 to 250 μm. Analysis showed that the driving force behind gelation relied on the large fiber content in the PP powder and the interaction between the powder particles and the solvent droplets. Larger particles exhibited higher antioxidant properties and formed gels through particle interactions, resulting in hard and brittle adsorbents with minimal oil/water loss. In contrast, smaller particles formed uniform gels due to solvent interactions but with higher water/oil losses. Increasing powder concentration resulted in harder gels due to the filling effect.
Conclusion
The development of a gel-like material from PP that mimics the properties of both oil gels and hydrogels is presented. The gelation mechanism of PP powders in the particle size range of 125 to 250 μm was studied. Due to the amphiphilic nature of PP powders, gels can be spontaneously formed when mixed with oil/water for a short time, which is a very reliable method for gel preparation. Chemical analysis and principal component analysis results highlighted the key role of 3D structures in the gels, while soluble cellulose helped retain water. The microstructure, physical properties, and functional performance of the gels were affected by factors such as the porous structure, particle size, powder concentration, and the interaction between powder particles and solvent droplets. Larger particles produced hard and brittle gels with minimal oil/water losses through particle interactions, while smaller particles formed homogeneous gels with solvent interactions and higher water/oil losses. Increasing powder concentrations resulted in harder gels due to a filling effect. These findings suggest a reliable approach to strengthen the grapefruit peel value chain, but also provide inspiration for the design of innovative fat substitutes with customized texture and functional properties for different food applications. Future research can focus on improving the hydrophobicity of PP powder and optimizing its effect as an oil gelling agent.
Identification, structural characterization and regulatory effects of key prebiotic components of soluble dietary fiber from the spongy layer of grapefruit peel on intestinal flora
Abstract
The key prebiotic components of soluble dietary fiber from the spongy layer of grapefruit peel (GSLSDF) were identified, and their structural characteristics and regulatory effects on intestinal microorganisms were studied. First, two components, GSLSDF-1 and GSLSDF-2, were isolated from GSLSDF, and GSLSDF-1 showed good prebiotic activity. It was then found that GSLSDF-1 had low molecular weight and crystallinity, loose and porous microstructure, and high glucose content. At the same time, GSLSDF-1 is a glucan with a main chain connected by β-1,4 glycosidic bonds and branched by β-1,6 glycosidic bonds. These structural characteristics are important reasons for the good prebiotic activity of GSLSDF-1. Finally, the regulatory effect of GSLSDF-1 on intestinal flora in in vitro fecal fermentation was analyzed. Compared with the blank group and the GSLSDF group, GSLSDF-1 increased the relative abundance of Lactobacillus, Bacteroides, Bifidobacterium, and Faecalibacterium, while reducing the relative abundance of Clostridium and Clostridium. In addition, GSLSDF-1 promoted the production of short-chain fatty acids (SCFAs) by regulating the synthesis pathway of intestinal microorganisms, while GSLSDF-1 inhibited the synthesis of intestinal microorganisms NH3-N. In summary, GSLSDF-1 is a key prebiotic component of GSLSDF and can effectively optimize the composition of intestinal microorganisms.
Conclusion
The key prebiotic component of GSLSDF (GSLSDF-1) was separated and its structure was characterized. The results of molecular weight, XRD, monosaccharide composition and SEM analysis showed that GSLSDF-1 had low molecular weight and crystallinity, high glucose content, loose and porous microstructure, and was easily absorbed and utilized by probiotics. In addition, the results of methylation and nuclear magnetic resonance analysis showed that GSLSDF-1 is a glucan with a main chain connected by β-1,4 glycosidic bonds and β-1,6 glycosidic bonds as branches, which has a good probiotic proliferation effect. In addition, GSLSDF-1 can increase the relative abundance of beneficial intestinal genera (Lactobacillus, Bacteroides, Bifidobacterium and Enterobacterium), reduce the relative abundance of harmful intestinal genera (Clostridium and Clostridium), promote the production of SCFAs, and inhibit the production of NH3-N. It can be seen that GSLSDF-1 can not only effectively promote the growth of probiotics, but also optimize the composition of intestinal microorganisms, and has potential application prospects in the food industry.
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