*2.1. Flour Preparation*

Lots of 4 kg from Ab and Po mushroom species were purchased from a local market in Mineral de la Reforma (Hidalgo, Mexico). Mushrooms were carefully selected based on visual appearance (light color without visible damage) and then rinsed, drained and cut in 5 mm-thick slices. Pieces of Ab were immersed in an acetic acid solution (2%) at 80 ◦C for 10 min and water-cooled at 4 ◦C to prevent enzymatic reactions. After draining o ff the excess liquid, the samples were dried in air-recirculating oven (CE5F, Shel Lab, Cornelius, OR, USA) at 60 ± 3 ◦C for 18 h, milled in a UDY cyclone sample mill (UDY Corp., Fort Collins, CO, USA) and sleeved through a 0.5 mm mesh. The resultant flours were placed in hermetic polyethylene bags and stored in the dark at room temperature until use.

#### *2.2. Manufacture of Frankfurter-Type Sausages*

Frankfurters were elaborated in the Meat Technology Centre (Ourense, Spain). Five formulations were designed to reduce fat (30% and 50% reductions) and salt, phosphates and caseinate (50% reduction) by the addition of Ab and Po flours (2.5% and 5.0%), comparing with the control formulation (C) elaborated with 25% fat and 1.5% salt, 2% of sodium caseinate and 0.5% of phosphates (Table 1). MF-Ab and MF-Po were the codes to identify sausages with 30% of fat reduction (medium-fat) and 50% of salt-phosphates-caseinate reduction, and with 2.5% Ab and Po flours, respectively. LF-Ab and LF-Po were the codes used for the sausages with 50% fat reduction (low-fat) and 50% salt-phosphates-caseinate reduction, and 5.0% Ab and Po flour added, respectively. MF-PoAb were assigned to identify the sausages with 30% fat reduction and 50% salt-phosphates-caseinate reduction, incorporated with 5.0% Ab and Po mix flour (2.5% each one).

Before the manufacturing process, sodium chloride and sodium ascorbate were added to the meat cut in 1 cm cubes with a rest period of 2 h. The lean and fat were minced, using plates of 8 mm and 6 mm respectively in a refrigerated mincer machine (La Minerva, Bologna, Italy). Potato starch and 50% of total sodium caseinate (dissolved in water) were previously added to the meat. Then, the rest of ingredients with the fat were added and mixed to homogeneity in a chilled cutter (TALSA K30 0542, Talsabell S.A., Valencia, Spain). Meat batter was stuffed into 25 mm collagen casings with an automatic equipment (SIA, Junior, Barcelona, Spain) forming 10 cm frankfurters.

The raw sausages were cooked in a temperature-controlled bath-water (Marmite Mera REA-505, Talsa, Talsabell S.A., Valencia, Spain) at 90 ◦C for 20 min. Then, the cooked sausages were cooled in an ice water-bath. Four frankfurters were vacuum packed (FRIMAQ V900, Lorca, Spain) in each polyethylene bag, pasteurized at 90 ◦C for 30 min and kept at 2 ◦C storage until the laboratory analysis during the 90-days storage period. Four packages of frankfurters from each batch were taken at 0, 30, 60 and 90 days of storage. All analyses were carried out in triplicate for each formulation. Chemical composition and amino acid profile were evaluated only on day 0. After the sampling for microbial analysis, the sausages were oxygenated for 30 min at room temperature for the rest of analyses.


**Table 1.** Formulation (g) of different frankfurters with edible mushroom flour.

1 Batches: Control (25% fat, 1.5% salt, 2% Sodium caseinate and 0.5% phosphates), MF-Ab (30% fat reduction, 50% salt reduction, 2.5% Ab), MF-Po (30% fat reduction, 50% salt reduction, 2.5% Po), LF-Ab (50% fat reduction, 50% salt reduction, 5.0% Ab), LF-Po (50% fat reduction, 50% salt reduction, 5.0% Po) and MF-PoAb (30% fat reduction, 50% salt reduction, 2.5% Ab and 2.5% Po).
