NDFS 251 exam 1

 is the degree to which a single sample would return the same value when tested multiple times; repeatability. 

a measure of how close the obtained value 

or difference tests show whether people can tell a difference between two products

• Select the odd/different sample.
• 

• Select the sample that matches the reference. 
• 

• Are the samples the same or different?
• 

• or "hedonic scale" tests indicate people's opinion of a product and/or attributes.
• ex. Just about right 

typically use trained panelists and go into detail  about specific elements of the product

A specific approach to descriptive testing where panelists are trained to identify specific attributes and to indicate attribute strengths on a continuum.  Used to make subjective analysis more objective.

composed of molecules of low molecular weight, which, when added to water below their saturation point, dissolve completely to form clear non-opaque solutions.

composed of molecules of higher molecular weight, but have either enough interaction with water or enough repulsion from each other to keep them from settling out.  normally translucent or partially cloudy.  can form gels.

 consist of compounds of high molecular weight, whuch do not have sufficient intermolecular forces to stay uniformily dispersed on a permenant basis.  tyoically settle out over time, some fairly quickly and others over a more extended period.

cooling direct transfer of energy from molecule to the next, without involving significant motion or flow.  Energy moves laterally from one layer to the next, which takes considerable time.

involves an element of motion or flow, which allows an indivdual high-energy molecule ( heated) to be exposed to many unheated molecules in succession, so that the heat energy is transfered to many different molecules fairly rapidly.

 involves transfer of energy to ambient air during phase change of water from liquid to gas.

 at same temp.

• Cu²⁺ + RCHO --> RCOO^- + Cu₂O(red) 
• all sugars are reducing sugars except sucrose

Sucrose + H₂O - invertase acid-> fructose/glucose

defined as percent sugar (by weight) dissolved in an aqueous solution.  Since many juices and other foods are comprised mainly of water and sugar, "brix" is often used synonymously with dissolved solutions.  can be measured by refractive index.( refractometer) 

• made by heating sugar solutions to saturation, then cooling to super saturation with stirring.  Stirring allows the sugar molecules to interact to form a crystalline lattice.  If they are stirred hot they tend to form larger crystals, whereas many small crystals will be formed if stirred at a lower temperature.
• ex. fondant, fudge.
•  

 In making these the goal is to inhibit crystallization.  this can be prevented in two ways.  interrferring agents.  quick cooling.

When dealing with sucrose based confections, presense of compounds other than water and sugar will generally interfere with sucrose crystilazation.  sugars other than sucrose, as well as fat, proteins, etc. are all interferring agents.  

_{super saturated --> super cooled}

ex.  peanut brittle, caramel

no ball

a definite ball but soft

a ball that is firm to the touch

a ball that is plastic when handled. 

threads present but not brittle

Threads which are brittle

118

152

concentration expression inducating the number of equivalents per liter

of an acid is the quanity of acid required to furnish one mole of H^+.

contains specified level of milkfat and nonfat milk solids

egg

milkfat replaced by vegetable or other animal fat

a low fat version of ice cream characterized by addition of a fruit, cocoa, or confectionary flavoring 

As ice crystals are scraped off, air is also being incorprated into the mix. 

The amount of air introduced into the mix