Rambutan (Nephelium lappaceum L.) is a tropical fruit that is originally from Southeast Asia and it was introduced to Mexico in the 1960s; the fruit’s peel is known to possess ellagitannins such as ellagic acid which give the peel great biological activity; solid-state fermentation has been used to obtain said compounds and rambutan peel can be used as a fermentation support/substrate; this work aims to obtain, identify and quantify ellagic acid obtained via SSF with a strain of yeast. The water-absorption index and the support’s maximum moisture were determined. To determine the ideal conditions for ellagic acid accumulation, a Box–Behnken 3^k experimental design was applied using variables such as temperature, moisture and inoculum. The maximum accumulation time of ellagic acid via solid-state fermentation was determined to be 48 h with ideal conditions of 30 °C, 60% moisture and 1.5 × 10⁷ cells/g using S. cerevisiae, and high-performance liquid chromatography was used to identify ellagic acid, geraniin and corilagin as the most abundant compounds. The maximum recovery of ellagic acid was 458 ± 44.6 mg/g. HPLC/ESI/MS analysis at 48 h fermentation showed biodegradation of geraniin and corilagin due to ellagic acid. Mexican rambutan peel has been demonstrated to be a suitable substrate for SSF.

Bioactive compounds are secondary metabolites widely studied for their benefits to human health. They are distributed in various fruit, vegetable, and plant peels. The application of sustainable techniques for the extraction of these compounds is being implemented, assisted extraction by solid-state fermentation is a sustainable and effective alternative for the recovery of bioactive compounds by using agro-industrial waste as a raw material for extraction, this being a green process, easy for implementation, and it has low water and energy consumption. This research presents the biological properties of some of the most used bioactive compounds in the industry, as well as the advantages and factors that influence solid-state fermentation and the different processes for their recovery and/or production. The production of bioactive compounds using both continuous and discontinuous processes come with unique advantages and challenges. The choices between these methods depend on specific production objectives, scalability needs, and the availability of resources. As a result, ongoing advancements are refining these methods, enabling more sustainable and efficient production of bioactive compounds.

Rambutan peel, an abundant agro-industrial by-product, is a rich source of ellagitannins (ETs) and represents a promising substrate for the sustainable production of ellagic acid (EA) through solid-state fermentation (SSF). This study aimed to optimize EA release from rambutan peel ETs by SSF using Saccharomyces cerevisiae 227 in column reactors. We applied a central composite design (CCD) to evaluate and optimize the effects of temperature, NaCl concentration, and peptone supplementation on EA production. We also used HPLC/ESI/MS to identify and quantify EA. Maximum EA yields were obtained under central experimental conditions (treatments 15 and 16: 35 °C, 0.53 g/L NaCl, and 8 g/L peptone), reaching 8.36 ± 1.58 and 8.23 ± 0.52 mg/g, respectively. The predictive model estimated a maximum EA production of 8.29 mg/g, experimentally validated, at 34.6 °C, 0.58 g/L NaCl, and 8.26 g/L peptone, yielding 8.27 ± 0.47 mg/g. HPLC/ESI/MS analysis further confirmed EA formation and the presence of biodegradation products derived from geraniin and corilagin, indicating effective ET biotransformation. These findings establish optimized conditions for EA production from rambutan peel ETs via SSF and demonstrate the feasibility of implementing a sustainable bioprocess for the valorization of this agro-industrial residue.

Ellagitannins (ETs) derived from rambutan (Nephelium lappaceum L.) peel are polyphenols that have gained prominence in the food and nutraceutical industries due to their high bioactivity. The objective of this study was to evaluate the encapsulation efficiency (EE) of ETs obtained from rambutan peel in sodium alginate beads, as well as their effect on cell viability and antioxidant potential. ETs were extracted and semi-purified using Amberlite XAD-16 resin and identified by HPLC/ESI/MS. To determine the encapsulation efficiency, a 3^k Box–Behnken experimental design was employed, evaluating the influence of ET concentration (1000, 2000, and 3000 ppm), sodium alginate (1, 2, and 3%), and CaCl₂ (5, 10, and 15 mM). Cell viability was assessed in HEK-293 and 3T3 cell lines, and antioxidant potential was determined through ABTS, DPPH, and FRAP assays. The results showed a maximum EE of 55% under conditions of 3000 ppm ETs, 2% sodium alginate, and 5 mM CaCl₂. Cell viability assays confirmed that both the crude extract and the ET-loaded capsules possess excellent biocompatibility, maintaining values above 70%. Furthermore, the capsules demonstrated significant antioxidant potential (ABTS 76%, DPPH 65%, FRAP 1.11 mmol TE/L) compared to the control (sodium alginate). These findings position the ET-loaded rambutan peel capsules as a promising alternative for the development of functional products in the food industry.