Prevention of the development of polluting characteristics in cooking water residue from nixtamalisation of corn by removing solid lime particles

Abstract

Summary Removing solid lime particles (SLP) may help to prevent polluting characteristics of corn cooking wastewater (nejayote). The objective of this study was to evaluate the polluting characteristics of nejayote and characteristics of nixtamal, masa and tortilla using SLP‐free solutions (SLPF) for the nixtamalisation process. Two SLPF treatments: calcium hydroxide (CHYDROX) and calcium oxide (COXIDE) were compared against traditional nixtamalisation (TRADNIX). Polluting characteristics including pH, settleable solids, total hardness, alkalinity and chemical oxygen demand (COD) reduced by 29.5% and 24.3%, 61.9% and 63.3%, 46.3% and 54.7%, 43.3% and 55.1%, 41.1% and 67.7% in CHYDROX and COXIDE, respectively, compared to TRADNIX. Masas and tortillas from SLPF treatments were whiter than those from TRADNIX. Moisture in SLPF tortillas was lower by 4.3–6.3% compared to TRADNIX. Tortillas from SLPF treatments had higher maximum tensile strength (0.04–0.08 N mm−2) than TRADNIX. Removing SLP is a viable strategy for preventing pollution from the nixtamalisation process.

Bioremediation with an Alkali-Tolerant Yeast of Wastewater (Nejayote) Derived from the Nixtamalization of Maize

“…The approximately 75 L of water employed for the nixtamalization of 50 kg of maize generates a similar quantity of nejayote [4]. In Mexico alone, around 14.4 million m 3 of highly contaminated wastewater is produced each year from this process [5][6][7]. The contamination stems mainly from elevated levels of the following: pH (up to 12), COD (2500-40,000 mg O 2 L −1 ), biochemical oxygen demand (BOD) (190-8100 mg O 2 L −1 ), and inorganic material.…”

“…The contamination stems mainly from elevated levels of the following: pH (up to 12), COD (2500-40,000 mg O 2 L −1 ), biochemical oxygen demand (BOD) (190-8100 mg O 2 L −1 ), and inorganic material. The latter is due to the abundance of calcium (about 1526 mg L −1 ) derived from the limewater [5,[7][8][9][10]. Nejayote far exceeds Mexican norms for the disposal of wastewater, which allows for a maximum COD of 150 mg O 2 L −1 and pH of 10 [11,12].…”

“…Nejayote far exceeds Mexican norms for the disposal of wastewater, which allows for a maximum COD of 150 mg O 2 L −1 and pH of 10 [11,12]. Unfortunately, most of this wastewater is thrown into bodies of water or storm sewers [5][6][7].…”