title: Moisture-induced caking of beverage powders.
abstract: BACKGROUND
  Beverage powders can exhibit caking during storage due to high temperature and moisture conditions, leading to consumer dissatisfaction. Caking problems can be aggravated by the presence of sensitive ingredients. The caking behaviour of cocoa beverage powders, with varying amounts of a carbohydrate sensitive ingredient, as affected by climate conditions was studied in this work. Sorption isotherms of beverage powders were determined at water activities (a(w) ) ranging from 0.1 to 0.6 in a moisture sorption analyser by gravimetry and fitted to the Brunauer-Emmett-Teller (BET) or the Guggenheim-Anderson-de Boer (GAB) equation. Glass transition temperatures (T(g) ) at several a(w) were analysed by differential scanning calorimetry and fitted to the Gordon-Taylor equation. Deduced T(g) = f(a(w) ) functions helped to identify stability or caking zones. Specific experimental methods, based on the analysis of mechanical properties of powder cakes formed under compression, were used to quantify the degree of caking. Pantry tests complemented this study to put in evidence the visual perception of powder caking with increasing a(w) .
  
  
  RESULTS
  The glass transition approach was useful to predict the risks of caking but was limited to products where T(g) can be measured. On the other hand, quantification of the caking degree by analysis of mechanical properties allowed estimation of the extent of degradation for each product.
  
  
  CONCLUSIONS
  This work demonstrated that increasing amounts of a carbohydrate sensitive ingredient in cocoa beverages negatively affected their storage stability.
authors.affiliation: Nestlé Product Technology Centre Orbe, Route de Chavornay 3, CH-1350 Orbe, Switzerland. BrunoEdgar.ChavezMontes@rdor.nestle.com
authors.forename: Edgar
authors.initials: E
authors.lastname: Chávez Montes
authors.forename: Nadia Ardila
authors.initials: NA
authors.lastname: Santamaría
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Gumy
authors.forename: Philippe
authors.initials: P
authors.lastname: Marchal
mesh_terms: D000327:Adsorption; D001628:Beverages / Q000032:analysis*; D002099:Cacao / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D005503:Food Additives / Q000009:adverse effects / Q000737:chemistry*; D005511:Food Handling; D006358:Hot Temperature / Q000009:adverse effects; D055595:Mechanical Phenomena; D044367:Phase Transition; D011786:Quality Control; D012212:Rheology; D044366:Transition Temperature; D014867:Water / Q000032:analysis*
chemical_list: D005503:Food Additives; D014867:Water