## 2 Materials and Methods
To provide a quality control for the qualitative assays (broth), 50 \(\upmu\)L of each strain was inoculated in a sterile TSB bottle, sterilized in an autoclave, and incubated at 30 \(\pm\) 1 \({}^{\circ}\)C for 24-48 h.  
The colony count was performed either manually or using an automatic colony counter (SphereFlash(r), IULmicro, Barcelona, Spain). Physicochemical properties  
To check that each culture medium had the required pH values, the pH was measured with a pH meter (Crison GLP21, Barcelona, Spain), before and after sterilization (before pouring onto a sterile Petri dish). The pH was measured at different times after sterilization in a microwave oven (7 min, 10 min, 13 min, and 15 min) and after autoclaving sterilization (control). Assessment of temperatures achieved in the microwave during sterilization  
The temperature of the glass bottle was measured with an infrared thermometer (Helect, Shenzhen, China) every 10 s during the sterilization cycle, as an indicative measure of the degrees reached inside the microwave oven. Sterility test  
In order to determine the necessary duration at which the culture medium was completely sterile in the microwave oven equipped with a water bath, 250 mL bottles of TSA were produced, and several sterilization durations (3 min, 5 min, and 7 min) were tested at 1000 W, without inoculating the micro-organisms in the medium. Dehydrated culture medium was mixed with 250 mL of deionized water, after which the bottle was closed with the special cap and sticker (Figure 1) and placed in a water bath in a microwave oven for the mentioned durations. The resulting plates were incubated at 32.5 \(\pm\) 2.5 \({}^{\circ}\)C for 24-48 h.  
With the media prepared for the optimal exposure time to obtain sterile plates, a quality control of the sterility test was performed, according to ISO 11333 (ISO 11133:2014/amended 1:2018) [19], keeping the plates and broth for 7 days, as follows: the TSA plates and TSB bottles were incubated at 32.5 \(\pm\) 2.5 \({}^{\circ}\)C, the SDA plates and Sabouraud dextrose broth at 22.5 \(\pm\) 2.5 \({}^{\circ}\)C, and the VRBG plates at 37 \(\pm\) 2.5 \({}^{\circ}\)C.  
Kinetics of microbial destruction in the microwave oven  
The bacterial strain _Escherichia coli_ ATCC 8739 was obtained from slant tubes (RPD S.L.). Spores from _Bacillus subtilis_ ATCC 6633 were obtained after a thermal shock at 80 \({}^{\circ}\)C for 10 min after 7-day cultures (maintained at 32.5 \(\pm\) 2.5 \({}^{\circ}\)C) and _Geobacillus stearothermophilus_ ATCC 7953 spores were taken from ampoules (Sterikon(r) plus bioindicator, MERCK, Rahway, NJ, USA). Then, 50 \(\upmu\)L of suspension containing 10\({}^{6}\) CFU/mL bacteria or spores was injected into a test bottle (5 \(\times\) 10\({}^{4}\)/bottle), which was exposed to a microwave at a power of 1000 W for periods of time ranging from 2.5 min to 20 min (depending on the destruction of each strain), with measurements taken every 30 s. The suspension was then cooled and poured into a sterile Petri dish and left to solidify. After incubation at 32.5 \(\pm\) 2.5 \({}^{\circ}\)C for 48 h (E. coli ATCC 8739 and _B. subtilis_ ATCC 6633) and 56 \(\pm\) 2.5 \({}^{\circ}\)C (_G. stearothermophilus_ ATCC 7953), the number of colonies was obtained. These tests were performed in triplicate. Statistical AnalysisThe data were analyzed using R software version 4.3.1. Generalized linear mixed models were used to model the bacterial counts (CFU), in which the linear predictor contains random effects, as well as fixed effects. Colonies (response) were modeled using Poisson's distribution, and in the case of overdispersion, the negative binomial distribution model was used. The different media were compared pairwise through multiple comparisons, using the Tukey method. The pH values of the different media, both reference and modified, were compared using the ANOVA test. The different media were compared pairwise, with a post hoc analysis using the Tukey test. A \(p\)-value less than 0.05 was considered statistically significant.