A food technologist is comparing two samples of strawberry jam — one with a sugar concentration of 65% and one with 20%. Which statement BEST explains why the 65% sugar jam has a longer shelf life?

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Question

A food technologist is comparing two samples of strawberry jam — one with a sugar concentration of 65% and one with 20%. Which statement BEST explains why the 65% sugar jam has a longer shelf life?

Accepted Answer

B. High sugar concentration lowers water activity, preventing microbial growth — A high sugar concentration (65%) creates a hypertonic environment with very low water activity, drawing water out of microbial cells by osmosis and preventing their growth. Sugar does not raise pH or increase temperature inside the jar. The idea that beneficial microbes compete with spoilage organisms is a common misconception not applicable here.

Answer

C. High sugar concentration provides nutrients that beneficial microbes use to outcompete spoilage organisms

Answer

D. High sugar concentration increases the temperature inside the jar, sterilising the contents

Answer

B. High sugar concentration lowers water activity, preventing microbial growth

Answer

A. High sugar concentration raises the pH, killing bacteria

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