Maestría en Tecnología de los Alimentos

Autor: Solórzano Cruz, M.R. 

Año: 2026

ABSTRACT

Stevia rebaudiana Bertoni contains steviol glycosides (SG) in its leaves — high-intensity natural sweeteners of growing relevance for the food, pharmaceutical, and nutraceutical industries. The production of purified SG extracts requires effective clarification steps that remove impurities such as proteins, polyphenols, and pigments while preserving SG recovery. The aim of this work was to optimize the clarification stage of hydroalcoholic extracts of steviaby evaluating the individual and sequential application of calcium oxide (CaO) and polyvinylpolypyrrolidone (PVPP) as clarifying agents, in combination with three extraction solvents of different polarity (water, 35% and 70% ethanol by weight).
Experiments were designed using factorial designs and Response Surface Methodology (RSM), evaluating as response variables the concentration of total SG (SGT), the proportion of rebaudioside A (Reb A), purity SGT), protein content, total polyphenols (TPC), tannins, lightness (L*), and total color difference (ΔE*). Optimal conditions were identified using the Derringer-Suich composite desirability function.
Ethanol 35% (w/w) produced the highest SGT concentration in crude extracts (24.47 ± 0.42g/L), significantly greater than water (18.85 g/L) and ethanol 70% (20.82 g/L). The proportion of Reb A in SGT remained stable at approximately 48% regardless of the  solvent. CaO clarification was the most effective treatment for purity improvement, yielding increases of up to 14.9 percentage points relative to the crude extract, and produced a highly significant bleaching effect (L*: up to +21 units; ΔE*: up to 30.8 units), depending on solvent composition. PVPP acted selectively on the polyphenolic fraction without significantly reducing SG content, consistent with its specific hydrogen-bonding adsorption mechanism towards polyphenols.
Sequential clarification (CaO+PVPP) was identified as the optimal strategy, with a composite desirability of D = 0.923, outperforming CaO alone (D = 0.710) and PVPP alone (D = 0.777). RSM-identified optimal conditions were ethanol 39.2% (w/w) as extraction solvent, followed by CaO clarification and subsequent PVPP addition at 3.1% (w/v), yielding a clarified extract with SGT ≈ 25.3 g/L, purity ≈ 44.0%, proteins ≈ 10.7 g/L (89% reduction vs. crude extract), TPC ≈ 1.2 g/L (85% reduction), and L* ≈ 57.0. The sequential clarification process proved robust across the three solvents evaluated, as no significant interactions between solvent and PVPP dose were detected. These results provide concrete operating conditions applicable to industrial-scale production of natural sweeteners from stevia.

Keywords: Stevia rebaudiana; steviol glycosides; clarification; PVPP; calcium oxide; Response Surface Methodology; optimization.

Correo: mrsolorzano.cruz@gmail.com

Autor: Centurión Rivas M. R.

Año: 2026

ABSTRACT

This study evaluated the optimization of the Cleaning In Place (CIP) system at the PMG bovine gelatin production plant (Minga Guazú, Paraguay), through the sequential implementation and comparison of three hygienization schemes during the period July – November 2025. Trial 1 (standard CIP – control) characterized the operational baseline of the process; Trial 2 incorporated an enzymatic step with ENZTRAT (2.5%, 45°C, 20 min) after the alkaline cleaning stage; and Trial 3 introduced the replacement of Oxonia ActiveTM sanitizer with Oxonia 150TM with a 50% reduction in dosing time.
The efficacy of each scheme was assessed using the TBF 300 biofilm detection test (Christeyns Food Hygiene) at critical low turbulence zones, complete microbiological analysis of the product at 3 hours post-CIP (Total Bacterial Count -TBC-, total and fecal coliforms, sulfite-reducing spores, Enterobacteriaceae and Salmonella spp.), microbiological analysis of the rinse water collected at the end of the sanitization stage of each CIP cycle, and a temporal product sampling plan at progressive post-CIP intervals to validate the extension of cleaning frequency.
Trial 1 results confirmed the immediate efficacy of the standard CIP, with all indicators within acceptance criteria at 3 hours post-CIP, but evidenced residual biofilm in low-turbulence zones and TBC exceeding the acceptance criterion (≤ 100 CFU/g) upon reaching the current CIP frequency in votators (scraped-surface heat exchangers; this term is retained hereafter) (338 ± 17 CFU/g at 24 h) and valve panel (240 ± 28 CFU/g at 48 h), values  corresponding to analyses performed on product samples (gelatin). The incorporation of the enzymatic step (Trial 2) completely eliminated biofilm from all evaluated surfaces and significantly reduced microbial reaccumulation rate, maintaining TBC within the criterion up to the target frequencies in all equipment. Trial 3 confirmed that the 50% reduction in sanitizer dosing time (from Oxonia ActiveTM, 200 s, to Oxonia 150TM, 100 s, a higher peracetic acid concentration formulation) did not compromise microbiological efficacy or biofilm control, with all peracetic acid residual concentration analyses within the acceptable range (0.20% 0.60%).
Temporal sampling validated the extension of CIP frequency from 24 to 48 hours in votators and from 48 to 96 hours in storage tanks, valve panel and Gelvap system (sterilizer and second effect evaporator).
It is concluded that the combination of periodic enzymatic step with Oxonia 150TM as sanitizer represents the most globally efficient CIP scheme, simultaneously achieving biofilm elimination, cleaning frequency extension and a significant reduction in peracetic acid consumption, with direct implications for operational sustainability and food safety of the production process.

Keywords: CIP, bovine gelatin, biofilm, ENZTRAT, peracetic acid, cleaning frequency, Oxonia 150.

Correo: raulcent.95@gmail.com