CONTROL (Fruit juice and related products)

Signiﬁcant hazards a r Salmonellae.

E. coli O157:H7. r Cryptosporidium parvum. r Patulin (apples and pears).

r Ochratoxin A (grapes).

(continued )

MICROORGANISMS IN FOODS 6

E CONTROL (Cont.) Control measures

Initial level (H 0 )

r Good agricultural practices. r Avoid use of dropped (“windfalls”) or damaged fruit. r Good hygienic practices.

Reduction (ΣR)

r Clean and wash fruit.

r 5-log 10 reduction through pasteurization or other treatment (see IV. Processing).

Increase (ΣI)

r Refrigerated storage (≤8 ◦

C) to prevent mycotoxin production.

Testing

r Equipment hygiene monitoring for pasteurized and

unpasteurized juice. r No product testing is recommended for canned or

concentrated fruit juices, purees, and nectars. r Formulation and process control monitoring.

Spoilage

r Yeast controlled by pasteurization, equipment hygiene,

temperature, and preservatives. r Alicyclobacillus control requires equipment hygiene control

for shelf stable products.

a Under particular circumstances, other hazards may need to be considered. Hazards to be considered. In principle, signiﬁcant hazards in fruit juices and related products are

the same as those of concern for the fresh fruits from which they are prepared (See Chapter 6). The hazards of most concern are the acid-tolerant bacterial pathogen E. coli O157:H7 and salmonellae; the mycotoxins patulin, produced by the growth of Pen. expansum in apples and pears, and ochratoxin A, from growth of Asp. carbonarius in grapes; and parasites such as Cryptosporidium parvum. Other hazards that sometimes need to be controlled are small round structured viruses and Hepatitis A, particularly if fruit is extensively handled and water is of questionable quality.

Control measures Initial level of hazard (H 0 ). Pre-harvest and post-harvest Good Agricultural Practices (GAP) are necessary to keep the contamination level of fruits as low as possible. Some pathogens are present in the soil so they easily contaminate the surface of fruits that are harvested. Use of dropped (“windfalls”) and/or damaged fruits must be avoided. Handlers also need to observe good hygiene practices during preparation of these products. Proper transportation, distribution, and packaging of the fruits are important measures to control the hazards. The control measures recommended for raw fruits and vegetables (see Chapters 5 and 6) apply to those used for production of non-pasteurized juices.

As is the case with with soft drinks, water is an important ingredient in reconstituted juices. Water of the appropriate quality can be obtained by a number of treatments, including ion exchange or reverse osmosis, ﬁltration or decontamination (e.g. chlorine or UV treatment).

Packaging can also be a source of microbiological contamination and should be properly cleaned and decontaminated, especially when recycled or re-used (e.g. return bottles).

Reduction of hazard (ΣR). Proper cleaning, washing, and sanitizing of fresh fruits are measures that reduce the level of contamination. Information about sanitizers applicable to fruits can be found

567 in Chapter 6. It must be noted that legal use of disinfectants differs from country to country. Cross-

SOFT DRINKS, FRUIT JUICES, CONCENTRATES, AND FRUIT PRESERVES

contamination between sanitized and non-sanitized fruits needs to be avoided.

A minimal standard of 5-log 10 reduction is advocated (e.g. FDA, 2001; Al-Taher and Knutson, 2004), although the initial contamination level of the fresh fruits should be suitably low. See Section IV for a discussion of various strategies to achieve this reduction.

Increase of hazard (ΣI). Factory hygiene is a major factor in the control of product stability, as most cases of yeast spoilage can be attributed to bad factory hygiene. Inadequate factory hygiene has also been linked to illness outbreaks involving fruit juices (Al-Taher and Knutson, 2004). Therefore, scrupulous attention to cleaning of the lines, ﬁllers, and cooling meter (if used) downstream from the pasteurizer is essential to prevent recontamination of the product. This should include thermal as well as chemical sanitation. Such processes are essential in products without preservatives, as any kind of adventitious fermentative yeast contamination will lead to spoilage. Aerial contamination with yeast and molds is another important factor to control. Major vectors such as dust and insects may import the microbes into

the factory environment from nearby sources (orchards, wineries, breweries, fruits/vegetables storage facilities).

C) is required to prevent fungal growth and subsequent potential mycotoxin formation. Refrigeration is also necessary for non-pasteurized fruit juices with lower acid concentrations such as tomato and melon to prevent growth of bacterial pathogens.

Proper storage under refrigeration (≤8 ◦

Stabilization though use of preservatives may also prevent an increase of hazards (See Section IV). Testing. Process control monitoring indicated for carbonated beverages is also appropriate for fruit

juice and related products. Because of the extensive heat treatment received, no product testing is recommended for canned or concentrated fruit juices, purees, and nectars.

Only raw materials (and not the ﬁnal product) should be analyzed microbiologically on a routine basis because the ingredients, after being combined, will generally be subjected to conditions that would tend to destroy the microorganisms. End-product sampling and inspection does not deliver reliable control, but microbiological enumeration can be used for veriﬁcation purposes for non-pasteurized and pasteurized juice. Several traditional methods, e.g. standard plate counts, counts of yeasts and molds or direct microscopic examination, are available for this (FDA, 1998; Downes and Ito, 2001). E. coli may

be used as an indicator of enteric pathogens in non-pasteurized juice. Automated impedance monitoring is a useful tool for rapid detection of yeasts in fruit juices (Zindulis, 1984, Deak and Beuchat, 1994) and heat-resistant microorganisms in a range of processes (Nielsen, 1992).

The simplest and most effective way to screen for preservative resistant yeasts is to spread or streak product onto plates of malt acetic acid agar (MAA) (Pitt and Richardson, 1973). MAA is a suitable medium for monitoring raw materials, process lines and products containing preservatives for resistant yeasts.

The diacetyl test maybe a tool for checking the sanitary conditions during the manufacture of raw materials, especially citrus and apple juices and concentrates (Murdock, 1967, 1968). This test detects diacetyl and acetylcarbinol, which are end products of bacterial growth and is speciﬁcally limited to lactic acid bacteria.

ATP photometry may be useful for rapid hygiene testing results. Spoilage. The shelf-life of non-pasteurized fruit juices is short due to enzymatic activity and presence

of high number of microorganisms. Product should be chilled (≤8 ◦

C) during storage. See Section III— Spoilage to refer to relevant spoilage agents in these products. Stabilization strategies using preservatives are discussed in Section IV—Processing.

MICROORGANISMS IN FOODS 6

The efﬁcacy of pasteurization is affected by the composition of the product, with high levels of sugars being protective, but low pH and presence of preservatives increasing the lethality of the heat process. It should be considered that pasteurization will not always destroy heat-resistant lactic acid bacteria, spores of thermotolerant Alicyclobacillus spp. and heat-resistant fungi (Byssochlamys fulva, Byss. nivea, Talaromyces macrosporus, and Neosartorya ﬁscheri). The most common manifes-

tation of spoilage are fermentation, when containers swell due production of CO 2 , and formation of cloudiness. Alicyclobacillus spp. does not produce gas, but may cause medicinal taints. The growth of Alicyclobacillus spp. is minimized when the product is kept chilled; however, psychrotrophic yeasts, and some lactic acid bacteria may spoil chilled products.

Due to low pH and a W , the growth of spoilage microorganisms in concentrated fruit juice is minimal. Alicyclobacillus spp. can grow at low pH, but needs oxygen and warm temperatures. Preservatives (CO 2 , sorbic acid, or benzoic acid) are commonly added to concentrated fruit juices to inhibit the growth of spoilage microorganisms and extend the shelf-life of the product. Post-processing contamination should

be avoided. Often aseptic/hot ﬁlling is used. Preservative resistant yeasts (Z. bailii, Z. rouxii, Sacc. cerevisiae, and Sacc. pombe) cause fermentative spoilage of fruit purees, nectars, cordials, preserves, and jams. They grow slowly but produce large amounts of CO 2 , causing distortion or explosion of containers. Because of its ability to adapt, it is important that populations of Z. bailii are not allowed to build up in the factory environment, where exposure to preservative-containing residues of product can lead to major problems. Post-processing contamination should be avoided (often aseptic/hot ﬁlling is used).

H Tea-based beverages The diversity of tea-based beverages does not allow for a generic summary of signiﬁcant hazards

and controls that would be appropriate for all products. For simple tea-based beverages, adequate pasteurization and avoidance of post-process recontamination prevent signiﬁcant safety and spoilage concerns. Addition of fruit juices may require use of controls discussed under fruit juices above. Addition of signiﬁcant protein sources, such as milk and soy protein, requires adequate validation of the control of potential hazards, including Cl. botulinum.

CONTROL (Fruit juice and related products)