Sugar overconsumption continues to increase worldwide and contributes to multiple health-related issues. Dairy foods represent a large market, grossing more than $125 billion per year worldwide. Consumer demands for healthier products are leading to a large push for sugar reduction in dairy foods. Sugar plays an important role in dairy foods, not only in flavor but also in texture, color, and viscosity. Replacing sugar can have negative effects, making substitution inherently difficult. Natural and artificial nonnutritive sweeteners exist for sugar reduction. Natural nonnutritive sweeteners are popular, particularly for label appeal, but many consumers still prefer the taste of artificial nonnutritive sweeteners. Sweet taste perception can also be affected by texture of the food matrix and the presence of fat. Other sugar reduction techniques include hydrolysis of lactose, ultrafiltration, and direct reduction. This review will address the role of sugar, alternative sweeteners, and sugar reduction in ice cream, yogurt, and flavored milk.

Calcium-chelating salts (CCS), such as phosphates and citrates, are often added to milk systems to modify physical properties like heat stability. The objective of this study was to investigate the effect of binary CCS mixtures on the properties of casein (CN) micelles including the distribution of Ca between the soluble and CN-bound states. Six binary CCS mixtures were prepared from 4 different types of CCS [i.e., trisodium citrate (TSC), disodium phosphate (DSP), tetrasodium pyrophosphate (TSPP), and sodium hexameta phosphate (SHMP)] by combining 2 CCS at a time in 5 different proportions (8.3:91.7, 29.2:70.8, 50:50, 70.8:29.2, and 91.7:8.3). Different concentrations of these mixtures (0, 0.1, 0.3, 0.5, and 0.7% wt/wt) were added to milk protein concentrate solutions (5% wt/wt) at pH 5.8. The ability of CCS to disperse CN particles and its interaction with Ca were assessed from turbidity measurements, acid-base titration behavior, and the quantity of CN-bound Ca and inorganic phosphate (Pi). Turbidity and the buffering peak at pH ∼5.0 during acid titration decreased with an increasing concentration of CCS. This was due to the chelation of Ca and the dispersion of CN micelles. The presence of TSC in mixtures decreased the amount of CN-bound Ca and Pi; however, the presence of TSPP in mixtures increased CN-bound Ca and Pi. When DSP was present at high proportions in mixtures of CCS, the CN-bound Ca and Pi slightly increased. When SHMP was used in mixtures of CCS, CN-bound Ca and Pi increased with the use of a low proportion of SHMP but decreased when SHMP was used at high proportions in the mixture. Combinations of DSP-TSPP used in the proportions 29.2:70.8, 50:50, and 70.8:29.2 resulted in the gelation of milk protein concentrates when the total CCS concentration was ≥0.3%. These results indicated that the type of CCS present in a mixture modified CN properties by various mechanisms, including chelation of Ca, dispersion of CN micelles, and formation of new types of Ca-CCS complexes. The type of interaction between the newly formed Ca-CCS complexes and the dispersed CN depended on the proportion, concentration, and type of CCS present in the mixtures. This information is useful in understanding how mixtures of CCS affect CN properties.

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In this investigation, the application of citric acid was explored for the removal of extracellular polymeric substance (EPS) from waste activated sludge (WAS), followed by ultrasonic pretreatment, which enhanced the subsequent anaerobic biodegradability. EPS was removed with 0.05g/g SS of citric acid. The chemical oxygen demand (COD) solubilization and suspended solids (SS) reduction that occurred for specific energy input of 171.9kJ/kg TS, in deflocculated (EPS removed and ultrasonically pretreated) sludges were found to be 22.70% and 20.28% and was comparatively higher, than the flocculated (with EPS and ultrasonically pretreated). The biogas yield potential of flocculated and deflocculated sludges (specific energy input - 171.9kJ/kgTS) was found to be 0.212L/(gVS) and 0.435L/(gVS), respectively. Accordingly, the deflocculation and ultrasonic pretreatment improved the anaerobic biodegradability efficiently. Thus, this chemo mediated sonic pretreatment is an effective method for enhancing biodegradability and improving clean energy generation from WAS.

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