Industrial Yogurt Manufacture: Monitoring of Fermentation Process and Improvement of Final Product Quality

Abstract

Lactic acid fermentation during the production of skim milk and whole fat set-style yogurt was continuously monitored by measuring pH. The modified Gompertz model was successfully applied to describe the pH decline and viscosity development during the fermentation process. The viscosity and incubation time data were also fitted to linear models against ln(pH). The investigation of the yogurt quality improvement practices included 2 different heat treatments (80 degrees C for 30 min and 95 degrees C for 10 min), 3 milk protein fortifying agents (skim milk powder, whey powder, and milk protein concentrate) added at 2.0%, and 4 hydrocolloids (kappa-carrageenan, xanthan, guar gum, and pectin) added at 0.01% to whole fat and skim yogurts. Heat treatment significantly affected viscosity and acetaldehyde development without influencing incubation time and acidity. The addition of whey powder shortened the incubation time but had a detrimental effect on consistency, firmness, and overall acceptance of yogurts. On the other hand, addition of skim milk powder improved the textural quality and decreased the vulnerability of yogurts to syneresis. Anionic stabilizers (kappa-carrageenan and pectin) had a poor effect on the texture and palatability of yogurts. However, neutral gums (xanthan and guar gum) improved texture and prevented the wheying-off defect. Skim milk yogurts exhibited longer incubation times and higher viscosities, whereas they were rated higher during sensory evaluation than whole fat yogurts.

Yoghurt and dairy snacks presented for sale to an Australian consumer: are they becoming less healthy?

“…However, in Western societies yoghurt has changed markedly from the traditional semi-firm curd product made from milk with perhaps salt (leben) or water (lassi) added (9) . Manufacturers now alter texture through the addition of milk solids, starch or gelatine (10) , alter taste with fruit and/or sweetening agents (9) and remove fat (9) . Health benefits are sought through fortification with vitamins and minerals (11) or addition of probiotic bacteria (12) or prebiotics such as inulin (13) .…”

Elaboración de una bebida utilizando subproductos de la industria láctea

“…Es por esto que los yogures con estabilizantes requieren menos tiempo de incubación. Además, los hidrocoloides pueden tener grupos aniónicos y catiónicos que reaccionan con partículas que se encuentran en la leche como proteínas o iones de calcio (Soukoulis et al, 2007). Soukoulis et al (2007) al analizar la fermentación y las mejoras de yogurt con diferentes tipos de proteínas e hidrocoloides, observaron que la goma xanthan previno los efectos del suero de leche; sin embargo, la alta temperatura afectó a la viscosidad.…”

“…Además, los hidrocoloides pueden tener grupos aniónicos y catiónicos que reaccionan con partículas que se encuentran en la leche como proteínas o iones de calcio (Soukoulis et al, 2007). Soukoulis et al (2007) al analizar la fermentación y las mejoras de yogurt con diferentes tipos de proteínas e hidrocoloides, observaron que la goma xanthan previno los efectos del suero de leche; sin embargo, la alta temperatura afectó a la viscosidad. Al coincidir con el estudio de Jiménez (2014) sobre la adición de biopolímeros en un jugo de maracuyá, para analizar la estabilidad fisicoquímica y antioxidante, cuando se usó 0,1 % de goma xanthan, la acidez fue de 0,58 %, ocurrió un incremento de la acidez a mayor porcentaje de la goma xanthan.…”

“…La agencia americana Food and Drug Administration (FDA) ha aprobado este polisacárido como aditivo alimentario puesto que varias investigaciones no han demostrado efectos adversos (García, Santos, Casas y Gómez, 2000). La función de un hidrocoloide es ligar agua, reaccionar con otros constituyentes del medio, estabilizar la red de proteína y evitar la liberación de agua (Soukoulis, Panagiotidis, Koureli y Tzia, 2007). En cuanto a sus propiedades fisicoquímicas, a un bajo pH, la disolución de la goma es rápida y completa e influye en la suspensión de componentes insolubles.…”

Contactless methods for quality evaluation of dairy products

“…They consider dairy products not only in terms of their taste and their direct nutritional value, but also in terms of their potential beneficial and health effects. This makes the traditional and well-established dairy products in an appropriate basis for the search and development of new functional foods and directs its efforts towards characterization of lactic acid microflora [27,32]. …”